PARTIAL UPGRADING OF BITUMEN WITH SUBSURFACE SOLVENT DEASPHALTING AND AT-SURFACE THERMAL TREATMENT

VALORISATION PARTIELLE DU BITUME AVEC DESASPHALTAGE AU SOLVANT DE SUBSURFACE ET TRAITEMENT THERMIQUE A LA SURFACE

English Abstract

Partial upgrading techniques that include subsurface deasphalting and mild thermal treatment at surface to produce a partially upgraded bitumen product are provided. The processes can include introducing an asphaltene-precipitating solvent into a subsurface formation to contact bitumen that includes a light fraction and a heavy fraction comprising asphaltenes, inducing in situ precipitation of at least a portion of the asphaltenes within the subsurface formation to produce a precipitated asphaltene material and a mobilized fluid comprising a deasphalted bitumen fraction, recovering the mobilized fluid as a production fluid comprising the deasphalted bitumen fraction, water, solids and a portion of the asphaltene-precipitating solvent while leaving a majority of the precipitated asphaltene material within the subsurface formation, separating deasphalted bitumen from the production fluid, and subjecting the deasphalted bitumen to a thermal treatment at about or below incipient coking conditions to produce the partially upgraded bitumen product.

French Abstract

Des techniques de valorisation partielles comprennent le désasphaltage en subsurface et un traitement thermique moyen en surface pour produire un produit de bitume partiellement valorisé. Les procédés peuvent comprendre lajout dun solvant de précipitation dasphaltènes dans une formation en subsurface pour entrer en contact avec le bitume comportant une fraction légère et une fraction lourde dasphaltènes, linduction sur place de la précipitation dau moins une partie des asphaltènes dans la formation en subsurface pour produire un matériau dasphaltènes précipités et un fluide mobilisé comprenant une fraction de bitume désasphalté, la récupération du fluide mobilisé comme fluide de production comprenant la fraction de bitume désasphalté, de leau, des solides et une partie du solvant de précipitation dasphaltènes, tout en laissant une majorité du matériau dasphaltènes précipités dans la formation en subsurface, la séparation du bitume désasphalté du fluide de production, et la soumission de ce bitume désasphalté à un traitement thermique dans des conditions égales ou inférieures à des conditions de cokéfaction initiales pour produire le produit de bitume partiellement valorisé.

Claims

59
CLAIMS
1. A process for producing a partially upgraded bitumen product, the process
comprising:
an in situ bitumen recovery operation comprising:
introducing an asphaltene-precipitating solvent into a subsurface
formation to contact bitumen contained in the subsurface formation, the
bitumen comprising a light fraction and a heavy fraction comprising
asphaltenes;
inducing in situ precipitation of at least a portion of the asphaltenes
within the subsurface formation to produce a precipitated asphaltene
material and a mobilized fluid comprising a deasphalted bitumen
fraction;
recovering the mobilized fluid as a production fluid comprising the
deasphalted bitumen fraction, water, solids and a portion of the
asphaltene-precipitating solvent while leaving a majority of the
precipitated asphaltene material within the subsurface formation;
separating deasphalted bitumen from the production fluid;
determining a property of the deasphalted bitumen; and
subjecting the deasphalted bitumen to a thermal treatment at about or below
incipient coking conditions to produce the partially upgraded bitumen product,
wherein the thermal treatment comprises adjusting an operating parameter of
the thermal treatment based on the property of the deasphalted bitumen
stream.
2. The process of claim 1, wherein all of the precipitated asphaltene material
is left within
the subsurface formation and the production fluid contains substantially none
of the
precipitated asphaltene material.
3. The process of claim 1 or 2, wherein introducing the asphaltene-
precipitating solvent
into the subsurface formation comprises injecting the asphaltene-precipitating
solvent
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via a horizontal injection well provided in the subsurface formation; and
wherein the
production fluid is recovered via a horizontal production well that is located
below the
horizontal injection well.
4. The process of any one of claims 1 to 3, wherein the asphaltene-
precipitating solvent
comprises an alkane solvent.
5. The process of claim 4, wherein the alkane solvent comprises propane,
butane,
pentane, hexane, heptane or a mixture thereof.
6. The process of claim 5, wherein the alkane solvent comprises propane.
7. The process of claim 5, wherein the alkane solvent comprises butane.
8. The process of claim 5, wherein the alkane solvent comprises pentane.
9. The process of any one of claims 1 to 8, wherein subjecting the deasphalted
bitumen
to the thermal treatment comprises heating the deasphalted bitumen to a
temperature
between 200 C and 475 C.
10. The process of any one of claims 1 to 8, wherein subjecting the
deasphalted bitumen
to the thermal treatment comprises heating the deasphalted bitumen to a
temperature
between 350 C and 450 C.
11. The process of any one of claims 1 to 10, wherein the thermal treatment is
performed
for a duration of up to 300 minutes.
12. The process of any one of claims 1 to 10, wherein the thermal treatment is
performed
for a duration below 60 minutes.
13. The process of any one of claims 1 to 10, wherein the thermal treatment is
performed
for a duration below 15 minutes.
14. The process of any one of claims 1 to 10, wherein the thermal treatment is
performed
for a duration between 5 minutes and 60 minutes.
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15. The process of any one of claims 1 to 10, wherein the thermal treatment is
performed
for a duration above 5 minutes.
16. The process of any one of claims 1 to 10, wherein the thermal treatment is
performed
for a duration of between 15 minutes and 240 minutes.
17. The process of any one of claims 1 to 16, wherein the thermal treatment is
performed
at a pressure between 50 psig and 1500 psig.
18. The process of any one of claims 1 to 16, wherein the thermal treatment is
performed
at a pressure between 50 psig and 1000 psig.
19. The process of any one of claims 1 to 18, wherein separating the
deasphalted bitumen
from the production fluid comprises removing water and solids from the
production
fluid.
20. The process of any one of claims 1 to 19, wherein separating deasphalted
bitumen
from the production fluid comprises recovering at least a portion of the
asphaltene-
precipitating solvent from the production fluid to obtain a recovered
asphaltene-
precipitating solvent for reintroduction into the subsurface formation.
21. The process of any one of claims 1 to 20, wherein introducing the
asphaltene-
precipitating solvent into the subsurface formation comprises vaporizing the
asphaltene-precipitating solvent and injecting the asphaltene-precipitating
solvent into
the subsurface formation in vapor phase.
22. The process of any one of claims 1 to 21, wherein conditions of the in
situ bitumen
recovery operation comprise providing a solvent-to-bitumen ratio of the
mobilized fluid
that is sufficiently high to cause the in situ precipitation of asphaltenes at
operating
extraction temperatures and pressures.
23. The process of claim 22, wherein the solvent-to-bitumen ratio of the
mobilized fluid is
sufficiently high to cause substantially all of the asphaltenes to precipitate
such that
the deasphalted bitumen fraction is fully deasphalted.
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24. The process of claim 22, wherein the solvent-to-bitumen ratio of the
mobilized fluid is
provided to cause partial precipitation of asphaltenes such that the
deasphalted
bitumen fraction comprises a reduced asphaltene content.
25. The process of any one of claims 1 to 24, wherein the property of the
deasphalted
bitumen comprises at least one of asphaltene content of the deasphalted
bitumen, a
compositional characteristic of the deasphalted bitumen, a viscosity of the
deasphalted
bitumen and a density of the deasphalted bitumen.
26. The process of any one of claims 1 to 25, further comprising combining the
deasphalted bitumen with a second hydrocarbon material to obtain a combined
deasphalted bitumen material that is subjected to the thermal treatment.
27. The process of claim 26, wherein combining the deasphalted bitumen with
the second
hydrocarbon material to obtain the combined deasphalted bitumen material is
performed when the property of the deasphalted bitumen is above or below a
given
threshold.
28. The process of claim 26 or 27, wherein the second hydrocarbon material
comprises a
second deasphalted bitumen.
29. The process of claim 28, wherein the second deasphalted bitumen is
obtained from a
second subsurface formation.
30. The process of any one of claims 25 to 29, further comprising subjecting
the
deasphalted bitumen to an at-surface deasphalting treatment to further reduce
the
asphaltene content of the deasphalted bitumen prior to the thermal treatment.
31. The process of claim 30, wherein the at-surface deasphalting treatment
comprises
using at least a portion of the recovered asphaltene-precipitating solvent as
deasphalting solvent.
32. The process of any one of claims 26 to 31, wherein the deasphalted bitumen
and the
second hydrocarbon material are combined in relative proportions so that the
combined deasphalted bitumen material has a predetermined composition based on
desired operating parameters of the thermal treatment.
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33. The process of any one of claims 1 to 25, further comprising combining
multiple
production fluids respectively obtained from a plurality of in situ recovery
wells to form
a combined production fluid, and separating the deasphalted bitumen from the
combined production fluid.
34. The process of any one of claims 1 to 33, wherein subjecting the
deasphalted bitumen
to the thermal treatment comprises maintaining the deasphalted bitumen in
liquid
phase during the thermal treatment.
35. The process of claim 34, wherein maintaining the deasphalted bitumen in
liquid phase
comprises providing conditions to cause a transfer of hydrogen from the heavy
fraction
to the light fraction directly in the liquid phase.
36. The process of any one of claims 1 to 35, wherein the thermal treatment
comprises
supplying the deasphalted bitumen to a thermal treatment vessel and
withdrawing the
partially upgraded bitumen product from the thermal treatment vessel as a
single
stream from a product outlet.
37. The process of claim 36, wherein the thermal treatment comprises feeding
the single
stream of partially upgraded bitumen product to a gas separator and removing
at least
a portion of a gas phase from the partially upgraded bitumen product.
38. The process of any one of claims 1 to 37, wherein adjusting the operating
parameter
of the thermal treatment in accordance with the property of the deasphalted
bitumen
comprises adjusting at least one of temperature, duration and pressure of the
thermal
treatment.
39. The process of any one of claims 1 to 38, wherein subjecting the
deasphalted bitumen
to the thermal treatment comprises adding an external source of hydrogen to
the
deasphalted bitumen.
40. The process of claim 39, wherein the external source of hydrogen is a
diatomic
hydrogen-containing gas.
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41. The process of any one of claims 1 to 40, wherein subjecting the
deasphalted bitumen
to the thermal treatment comprises adding a hydrogen transfer agent to the
deasphalted bitumen.
42. The process of claim 41, wherein the hydrogen transfer agent comprises
paraffins,
naphthenes, naphtheno-aromatics and/or aromatics.
43. The process of claim 41, wherein the hydrogen transfer agent comprises at
least one
of butane, propane, methane, tetralin, decalin, and anthracene.
44. The process of claim 41, wherein the hydrogen transfer agent comprises a
hydrogen
donor.
45. The process of claim 44, wherein the hydrogen donor comprises at least one
of tetralin,
decalin, synthetic crude oil, fractions of synthetic crude oil, tight oil,
shale oil and light
crude oils.
46. The process of any one of claims 1 to 45, further comprising diluting the
partially
upgraded bitumen product with a diluent to obtain a diluted bitumen product.
47. The process of claim 46, wherein the diluent comprises an aromatic
diluent, a
naphthenic diluent, natural gas condensates, synthetic crude, a fraction of
synthetic
crude oil or combinations thereof.
48. The process of claim 46 or 47, wherein the diluted bitumen product is
diluted to a
predetermined pipeline specification, and is also based on the determined
property of
the partially upgraded bitumen product.
49. The process of any one of claims 1 to 48, further comprising recovering
heat from the
partially upgraded bitumen product and reusing at least a portion of the
recovered heat
in the in situ bitumen recovery operation.
50. The process of claim 49, wherein the heat is at least partly reused for
pre-heating a
process stream that is part of the in situ bitumen recovery operation prior to
a unit
operation.
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51. The process of any one of claims 1 to 50, wherein the deasphalted bitumen
has a
variable composition over time.
52. The process of claim 51, wherein the deasphalted bitumen has a higher
asphaltene
content during an earlier stage of the in situ bitumen recovery operation, and
a lower
asphaltene content during a later stage of the in situ bitumen recovery
operation.
53. The process of claim 52, wherein the earlier stage comprises a startup
stage, and the
later stage comprises a normal operation stage of the in situ bitumen recovery
operation.
54. The process of any one of claims 51 to 53, further comprising controlling
the in situ
bitumen recovery operation or the thermal treatment or a combination thereof,
based
on the variable composition of the deasphalted bitumen.
55. The process of claim 54, wherein the thermal treatment is operated at
lower severity
conditions when the deasphalted bitumen has a higher asphaltene content, and
is
operated at higher severity conditions when the deasphalted bitumen has a
lower
asphaltene content.
56. The process of claim 55, wherein the thermal treatment is continuously
controlled
based on the variable composition of the deasphalted bitumen.
57. The process of claim 55, wherein the thermal treatment is intermittently
controlled
based on the variable composition of the deasphalted bitumen.
58. A process for producing a partially upgraded bitumen product, the process
comprising:
recovering a mobilized subsurface fluid as production fluid comprising a
deasphalted bitumen fraction as part of an in situ bitumen recovery operation,
comprising:
introducing an asphaltene-precipitating solvent into a subsurface
formation to contact bitumen contained in the subsurface formation, the
bitumen comprising a light fraction and a heavy fraction comprising
asphaltenes;
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inducing in situ precipitation of at least a portion of the asphaltenes within
the subsurface formation to produce a precipitated asphaltene material
and the mobilized subsurface fluid comprising the deasphalted bitumen
fraction; and
producing the mobilized subsurface fluid to the surface as the production
fluid that includes the deasphalted bitumen fraction, water, solids and a
portion of the asphaltene-precipitating solvent while leaving a majority of
the precipitated asphaltene material within the subsurface formation;
separating deasphalted bitumen from the production fluid;
determining a property of the deasphalted bitumen;
adjusting a variable related to the in situ bitumen recovery operation based
on
the property of the deasphalted bitumen to obtain a deasphalted bitumen
feedstock; and
subjecting the deasphalted bitumen feedstock to a thermal treatment at about
or below incipient coking conditions to produce the partially upgraded bitumen
product.
59. The process of claim 58, wherein all of the precipitated asphaltene
material is left
within the subsurface formation and the production fluid contains
substantially none of
the precipitated asphaltene material.
60. The process of claim 58 or 59, wherein introducing the asphaltene-
precipitating
solvent into the subsurface formation comprises injecting the asphaltene-
precipitating
solvent via a horizontal injection well provided in the subsurface formation;
and wherein
the production fluid is recovered via a horizontal production well that is
located below
the horizontal injection well.
61. The process of any one of claims 58 to 60, wherein the asphaltene-
precipitating
solvent comprises an alkane solvent.
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62. The process of claim 61, wherein the alkane solvent comprises propane,
butane,
pentane, hexane, heptane or a mixture thereof.
63. The process of claim 61, wherein the alkane solvent comprises propane.
64. The process of claim 61, wherein the alkane solvent comprises butane.
65. The process of claim 61, wherein the alkane solvent comprises pentane.
66. The process of any one of claims 58 to 65, wherein subjecting the
deasphalted
bitumen to the thermal treatment comprises heating the deasphalted bitumen to
a
temperature between 200 C and 475 C.
67. The process of any one of claims 58 to 65, wherein subjecting the
deasphalted
bitumen to the thermal treatment comprises heating the deasphalted bitumen to
a
temperature between 350 C and 450 C.
68. The process of any one of claims 58 to 67, wherein the thermal treatment
is performed
for a duration of up to 300 minutes.
69. The process of any one of claims 58 to 67, wherein the thermal treatment
is performed
for a duration below 60 minutes.
70. The process of any one of claims 58 to 67, wherein the thermal treatment
is performed
for a duration below 15 minutes.
71. The process of any one of claims 58 to 67, wherein the thermal treatment
is performed
for a duration between 5 minutes and 60 minutes.
72. The process of any one of claims 58 to 67, wherein the thermal treatment
is performed
for a duration above 5 minutes.
73. The process of any one of claims 58 to 67, wherein the thermal treatment
is performed
for a duration of between 15 minutes and 240 minutes.
74. The process of any one of claims 58 to 73, wherein the thermal treatment
is performed
at a pressure between 50 psig and 1500 psig.
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75. The process of any one of claims 58 to 73, wherein the thermal treatment
is performed
at a pressure between 50 psig and 1000 psig.
76. The process of any one of claims 58 to 75, wherein separating deasphalted
bitumen
from the production fluid comprises removing water and solids from the
production
fluid.
77. The process of any one of claims 58 to 76, wherein separating deasphalted
bitumen
from the production fluid comprises recovering at least a portion of the
asphaltene-
precipitating solvent from the production fluid to obtain a recovered
asphaltene-
precipitating solvent for reintroduction into the subsurface formation.
78. The process of any one of claims 58 to 77, wherein introducing the
asphaltene-
precipitating solvent into the subsurface formation comprises vaporizing the
asphaltene-precipitating solvent at surface, and injecting the asphaltene-
precipitating
solvent into the subsurface formation in vapor phase.
79. The process of any one of claims 58 to 78, wherein conditions of the in
situ bitumen
recovery operation comprise providing a solvent-to-bitumen ratio of the
mobilized fluid
that is sufficiently high to cause the in situ precipitation of asphaltenes at
operating
extraction temperatures and pressures.
80. The process of claim 79, wherein the solvent-to-bitumen ratio of the
mobilized fluid is
sufficiently high to cause substantially all of the asphaltenes to precipitate
such that
the deasphalted bitumen fraction is fully deasphalted.
81. The process of claim 79, wherein the solvent-to-bitumen ratio of the
mobilized fluid is
provided to cause partial precipitation of asphaltenes such that the
deasphalted
bitumen fraction comprises a reduced asphaltene content.
82. The process of any one of claims 58 to 81, wherein adjusting the variable
related to
the in situ bitumen recovery operation comprises adjusting at least one
operating
parameter related thereto.
83. The process of claim 82, wherein adjusting the operating parameter of the
in situ
bitumen recovery operation comprises at least one of modifying the type or
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composition of the asphaltene-precipitating solvent introduced into the
subsurface
formation, modifying an amount or rate of the asphaltene-precipitating solvent
introduced into the subsurface formation, adjusting a solvent-to-bitumen ratio
within
the subsurface formation or of the production fluid, adjusting a temperature
of the
asphaltene-precipitating solvent to be introduced in the subsurface formation,
adjusting a temperature within the subsurface formation, and adjusting heat
that is
provided to the reservoir.
84. The process of any one of claims 58 to 83, wherein adjusting the variable
related to
the in situ bitumen recovery operation comprises adjusting at least one
characteristic
of the deasphalted bitumen.
85. The process of any one of claims 58 to 84, wherein the property of the
deasphalted
bitumen comprises at least one of asphaltene content of the deasphalted
bitumen, a
compositional characteristic of the deasphalted bitumen, a viscosity of the
deasphalted
bitumen and a density of the deasphalted bitumen.
86. The process of any one of claims 58 to 85, further comprising combining
the
deasphalted bitumen with a second hydrocarbon material to obtain a combined
deasphalted bitumen material that is subjected to the thermal treatment.
87. The process of claim 86, wherein combining the deasphalted bitumen with
the second
hydrocarbon material to obtain the combined deasphalted bitumen material is
performed when the property of the deasphalted bitumen is above or below a
given
threshold.
88. The process of claim 86 or 87, wherein the second hydrocarbon material
comprises a
second deasphalted bitumen.
89. The process of claim 88, wherein the second deasphalted bitumen is
obtained from a
second subsurface formation.
90. The process of any one of claims 86 to 89, further comprising subjecting
the
deasphalted bitumen to an at-surface deasphalting treatment to further reduce
the
asphaltene content of the deasphalted bitumen prior to the thermal treatment.
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91. The process of claim 90, wherein the at-surface deasphalting treatment
comprises
using at least a portion of the recovered asphaltene-precipitating solvent as
deasphalting solvent.
92. The process of any one of claims 86 to 91, wherein the deasphalted bitumen
and the
second hydrocarbon material are combined in relative proportions so that the
combined deasphalted bitumen material has a predetermined composition based on
desired operating parameters of the thermal treatment.
93. The process of any one of claims 58 to 91, further comprising combining
multiple
production fluids respectively obtained from a plurality of in situ recovery
wells to form
a combined production fluid, and separating the deasphalted bitumen from the
combined production fluid.
94. The process of any one of claims 58 to 93, wherein subjecting the
deasphalted
bitumen to the thermal treatment comprises maintaining the deasphalted bitumen
in
liquid phase during the thermal treatment.
95. The process of claim 94, wherein maintaining the deasphalted bitumen in
liquid phase
comprises providing conditions to cause a transfer of hydrogen from the heavy
fraction
to the light fraction directly in the liquid phase.
96. The process of any one of claims 58 to 95, wherein the thermal treatment
comprises
supplying the deasphalted bitumen to a thermal treatment vessel and
withdrawing the
partially upgraded bitumen product from the thermal treatment vessel as a
single
stream from a product outlet.
97. The process of claim 96, wherein the thermal treatment comprises feeding
the single
stream of partially upgraded bitumen product to a gas separator and removing
at least
a portion of a gas phase from the partially upgraded bitumen product.
98. The process of any one of claims 58 to 97, wherein subjecting the
deasphalted
bitumen to the thermal treatment comprises adding an external source of
hydrogen to
the deasphalted bitumen.
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99. The process of claim 98, wherein the external source of hydrogen is a
diatomic
hydrogen-containing gas.
100. The process of any one of claims 58 to 99, wherein subjecting the
deasphalted
bitumen to the thermal treatment comprises adding a hydrogen transfer agent to
the
deasphalted bitumen.
101. The process of claim 100, wherein the hydrogen transfer agent comprises
paraffins,
naphthenes, naphtheno-aromatics and/or aromatics.
102. The process of claim 100, wherein the hydrogen transfer agent comprises
at least
one of butane, propane, methane, tetralin, decalin, and anthracene.
103. The process of claims 100, wherein the hydrogen transfer agent comprises
a
hydrogen donor.
104. The process of claim 103, wherein the hydrogen donor comprises at least
one of
tetralin, decalin, synthetic crude oil, fractions of synthetic crude oil,
tight oil, shale oil
and light crude oils.
105. The process of any one of claims 58 to 104, further comprising diluting
the partially
upgraded bitumen product with a diluent to obtain a diluted bitumen product.
106. The process of claim 105, wherein the diluent comprises an aromatic
diluent, a
naphthenic diluent, natural gas condensates, synthetic crude, a fraction of
synthetic
crude oil or streams thereof.
107. The process of claim 105 or 106, wherein the diluted bitumen product is
diluted to a
predetermined pipeline specification.
108. The process of any one of claims 58 to 107, further comprising recovering
heat from
the partially upgraded bitumen product and reusing at least a portion of the
recovered
heat in the in situ bitumen recovery operation.
109. The process of claim 108, wherein the heat is at least partly reused for
pre-heating a
process stream that is part of the in situ bitumen recovery operation prior to
a unit
operation.
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110. The process of any one of claims 58 to 109, wherein the deasphalted
bitumen has a
variable composition over time.
111. The process of claim 110, wherein the deasphalted bitumen has a higher
asphaltene
content during an earlier stage of the in situ bitumen recovery operation, and
a lower
asphaltene content during a later stage of the in situ bitumen recovery
operation.
112. The process of claim 111, wherein the earlier stage comprises a startup
stage, and
the later stage comprises a normal operation stage of the in situ bitumen
recovery
operation.
113. The process of any one of claims 110 to 112, further comprising
controlling the in situ
bitumen recovery operation or the thermal treatment or a combination thereof,
based
on the variable composition of the deasphalted bitumen.
114. The process of claim 113, wherein the thermal treatment is operated at
lower severity
conditions when the deasphalted bitumen has a higher asphaltene content, and
is
operated at higher severity conditions when the deasphalted bitumen has a
lower
asphaltene content.
115. The process of claim 114, wherein the thermal treatment is continuously
controlled
based on the variable composition of the deasphalted bitumen.
116. The process of claim 114, wherein the thermal treatment is intermittently
controlled
based on the variable composition of the deasphalted bitumen.
117. A process for producing a partially upgraded bitumen product, the process
comprising:
an in situ bitumen recovery operation comprising:
introducing an asphaltene-precipitating solvent into a subsurface
formation to contact bitumen contained in the subsurface formation, the
bitumen comprising a light fraction and a heavy fraction comprising
asphaltenes;
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inducing in situ precipitation of at least a portion of the asphaltenes
within the subsurface formation to produce a precipitated asphaltene
material and a mobilized fluid comprising a deasphalted bitumen
fraction;
recovering the mobilized fluid as a production fluid comprising the
deasphalted bitumen fraction, water, solids and a portion of the
asphaltene-precipitating solvent while leaving a majority of the
precipitated asphaltene material within the subsurface formation;
separating deasphalted bitumen from the production fluid;
subjecting the deasphalted bitumen to a thermal treatment at about or below
incipient coking conditions to produce the partially upgraded bitumen product;
determining a property of the partially upgraded bitumen product; and
adjusting an operating parameter of the thermal treatment based on the
determined property of the partially upgraded bitumen product.
118. The process of claim 117, wherein all of the precipitated asphaltene
material is left
within the subsurface formation and the production fluid contains
substantially none of
the precipitated asphaltene material.
119. The process of claim 117 or 118, wherein introducing the asphaltene-
precipitating
solvent into the subsurface formation comprises injecting the asphaltene-
precipitating
solvent via a horizontal injection well provided in the subsurface formation;
and wherein
the production fluid is recovered via a horizontal production well that is
located below
the horizontal injection well.
120. The process of any one of claims 117 to 119, wherein the asphaltene-
precipitating
solvent comprises an alkane solvent.
121. The process of claim 120, wherein the alkane solvent comprises propane,
butane,
pentane, hexane, heptane or a mixture thereof.
122. The process of claim 121, wherein the alkane solvent comprises propane.
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123. The process of claim 122, wherein the alkane solvent comprises butane.
124. The process of claim 122, wherein the alkane solvent comprises pentane.
125. The process of any one of claims 117 to 124, wherein subjecting the
deasphalted
bitumen to the thermal treatment comprises heating the deasphalted bitumen to
a
temperature between 200 C and 475 C.
126. The process of any one of claims 117 to 124, wherein subjecting the
deasphalted
bitumen to the thermal treatment comprises heating the deasphalted bitumen to
a
temperature between 350 C and 450 C.
127. The process of any one of claims 117 to 126, wherein the thermal
treatment is
performed for a duration of up to 300 minutes.
128. The process of any one of claims 117 to 126, wherein the thermal
treatment is
performed for a duration below 60 minutes.
129. The process of any one of claims 117 to 126, wherein the thermal
treatment is
performed for a duration below 15 minutes.
130. The process of any one of claims 117 to 126, wherein the thermal
treatment is
performed for a duration between 5 minutes and 60 minutes.
131. The process of any one of claims 117 to 126, wherein the thermal
treatment is
performed for a duration above 5 minutes.
132. The process of any one of claims 117 to 126, wherein the thermal
treatment is
performed for a duration of between 15 minutes and 240 minutes.
133. The process of any one of claims 117 to 132, wherein the thermal
treatment is
performed at a pressure between 50 psig and 1500 psig.
134. The process of any one of claims 117 to 132, wherein the thermal
treatment is
performed at a pressure between 50 psig and 1000 psig.
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135. The process of any one of claims 117 to 134, wherein separating the
deasphalted
bitumen from the production fluid comprises removing water and solids from the
production fluid.
136. The process of any one of claims 117 to 135, wherein separating the
deasphalted
bitumen from the production fluid comprises recovering at least a portion of
the
asphaltene-precipitating solvent from the production fluid to obtain a
recovered
asphaltene-precipitating solvent for reintroduction into the subsurface
formation.
137. The process of any one of claims 117 to 136, wherein introducing the
asphaltene-
precipitating solvent into the subsurface formation comprises vaporizing the
asphaltene-precipitating solvent at surface, and injecting the asphaltene-
precipitating
solvent into the subsurface formation in vapor phase.
138. The process of any one of claims 117 to 137, wherein conditions of the in
situ bitumen
recovery operation comprise providing a solvent-to-bitumen ratio of the
mobilized fluid
that is sufficiently high to cause the in situ precipitation of asphaltenes at
operating
extraction temperatures and pressures.
139. The process of claim 138, wherein the solvent-to-bitumen ratio of the
mobilized fluid
is sufficiently high to cause substantially all of the asphaltenes to
precipitate such that
the deasphalted bitumen fraction is fully deasphalted.
140. The process of claim 138, wherein the solvent-to-bitumen ratio of the
mobilized fluid
is provided to cause partial precipitation of asphaltenes such that the
deasphalted
bitumen fraction comprises a reduced asphaltene content.
141. The process of any one of claims 117 to 140, wherein the determined
property of the
partially upgraded bitumen product comprises at least one of asphaltene
content of the
partially upgraded bitumen product, a compositional characteristic of the
partially
upgraded bitumen product, a viscosity of the partially upgraded bitumen
product, a
density of the partially upgraded bitumen product, and an olefin content of
the partially
upgraded bitumen product.
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142. The process of any one of claims 117 to 141, further comprising combining
the
deasphalted bitumen with a second hydrocarbon material to obtain a combined
deasphalted bitumen material that is subjected to the thermal treatment.
143. The process of claim 142, wherein combining the deasphalted bitumen with
the
second hydrocarbon material to obtain the combined deasphalted bitumen
material is
performed when the property of the deasphalted bitumen is above or below a
given
threshold.
144. The process of claim 142 or 143, wherein the second hydrocarbon material
comprises a second deasphalted bitumen.
145. The process of claim 144, wherein the second deasphalted bitumen is
obtained from
a second subsurface formation.
146. The process of any one of claims 141 to 145, further comprising
subjecting the
deasphalted bitumen to an at-surface deasphalting treatment to further reduce
an
asphaltene content of the deasphalted bitumen prior to the thermal treatment.
147. The process of claim 146, wherein the at-surface deasphalting treatment
comprises
using at least a portion of the recovered asphaltene-precipitating solvent as
deasphalting solvent.
148. The process of any one of claims 142 to 147, wherein the deasphalted
bitumen and
the second hydrocarbon material are combined in relative proportions so that
the
combined deasphalted bitumen material has a predetermined composition based on
desired operating parameters of the thermal treatment.
149. The process of any one of claims 117 to 141, further comprising combining
multiple
production fluids respectively obtained from a plurality of in situ recovery
wells to form
a combined production fluid, and separating the deasphalted bitumen from the
combined production fluid.
150. The process of any one of claims 117 to 149, wherein subjecting the
deasphalted
bitumen to the thermal treatment comprises maintaining the deasphalted bitumen
in
liquid phase during the thermal treatment.
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151. The process of claim 150, wherein maintaining the deasphalted bitumen in
liquid
phase comprises providing conditions to cause a transfer of hydrogen from the
heavy
fraction to the light fraction directly in the liquid phase.
152. The process of any one of claims 117 to 151, wherein the thermal
treatment
comprises supplying the deasphalted bitumen to a thermal treatment vessel and
withdrawing the partially upgraded bitumen product from the thermal treatment
vessel
as a single stream from a product outlet.
153. The process of claim 152, wherein the thermal treatment comprises feeding
the
single stream of partially upgraded bitumen product to a gas separator and
removing
at least a portion of a gas phase from the partially upgraded bitumen product.
154. The process of any one of claims 134 to 153, wherein adjusting the
operating
parameter of the thermal treatment based on the determined property of the
partially
upgraded bitumen product comprises adjusting at least one of the temperature,
the
duration and the pressure of the thermal treatment.
155. The process of any one of claims 117 to 154, wherein subjecting the
deasphalted
bitumen to the thermal treatment comprises adding an external source of
hydrogen to
the deasphalted bitumen.
156. The process of claim 155, wherein the external source of hydrogen is a
diatomic
hydrogen-containing gas.
157. The process of any one of claims 117 to 156, wherein subjecting the
deasphalted
bitumen to the thermal treatment comprises adding a hydrogen transfer agent to
the
deasphalted bitumen.
158. The process of claim 157, wherein the hydrogen transfer agent comprises
paraffins,
naphthenes, naphtheno-aromatics and/or aromatics.
159. The process of claim 157, wherein the hydrogen transfer agent comprises
at least
one of butane, propane, methane, tetralin, decalin, and anthracene.
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160. The process of claims 157, wherein the hydrogen transfer agent comprises
a
hydrogen donor.
161. The process of claim 160, wherein the hydrogen donor comprises at least
one of
tetralin, decalin, synthetic crude oil, fractions of synthetic crude oil,
tight oil, shale oil
and light crude oils.
162. The process of any one of claims 117 to 161, further comprising diluting
the partially
upgraded bitumen product with a diluent to obtain a diluted bitumen product.
163. The process of claim 162, wherein the diluent comprises an aromatic
diluent, a
naphthenic diluent, natural gas condensates, synthetic crude, a fraction of
synthetic
crude oil or streams thereof.
164. The process of claim 162 or 163, wherein the diluted bitumen product is
diluted to a
predetermined pipeline specification, and is also based on the determined
property of
the partially upgraded bitumen product.
165. The process of any one of claims 117 to 164, further comprising
recovering heat from
the partially upgraded bitumen product and reusing at least a portion of the
recovered
heat in the in situ bitumen recovery operation.
166. The process of claim 165, wherein the heat is at least partly reused for
pre-heating a
process stream that is part of the in situ bitumen recovery operation prior to
a unit
operation.
167. The process of any one of claims 117 to 166, wherein the deasphalted
bitumen has
a variable composition over time.
168. The process of claim 167, wherein the deasphalted bitumen has a higher
asphaltene
content during an earlier stage of the in situ bitumen recovery operation, and
a lower
asphaltene content during a later stage of the in situ bitumen recovery
operation.
169. The process of claim 168, wherein the earlier stage comprises a startup
stage, and
the later stage comprises a normal operation stage of the in situ bitumen
recovery
operation.
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170. The process of any one of claims 167 to 169, further comprising
controlling the in situ
bitumen recovery operation or the thermal treatment or a combination thereof,
based
on the variable composition of the deasphalted bitumen.
171. The process of claim 170, wherein the thermal treatment is operated at
lower severity
conditions when the deasphalted bitumen has a higher asphaltene content, and
is
operated at higher severity conditions when the deasphalted bitumen has a
lower
asphaltene content.
172. The process of claim 171, wherein the thermal treatment is continuously
controlled
based on the variable composition of the deasphalted bitumen.
173. The process of claim 171, wherein the thermal treatment is intermittently
controlled
based on the variable composition of the deasphalted bitumen.
174. A process for producing a partially upgraded bitumen product, the process
comprising:
conducting an in situ bitumen recovery operation, comprising:
introducing an asphaltene-precipitating solvent into a subsurface formation
to contact bitumen contained in the subsurface formation, the bitumen
comprising a light fraction and a heavy fraction comprising asphaltenes, at
conditions to cause in situ precipitation of at least a portion of the
asphaltenes within the subsurface formation to produce a precipitated
asphaltene material and a mobilized fluid comprising a deasphalted
bitumen fraction;
recovering the mobilized fluid as a production fluid comprising the
deasphalted bitumen fraction, water, solids and a portion of the asphaltene-
precipitating solvent while leaving a majority of the precipitated asphaltene
material within the subsurface formation; and
separating deasphalted bitumen from the production fluid; and
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subjecting the deasphalted bitumen to a thermal treatment at about or below
incipient coking conditions to produce the partially upgraded bitumen product.
175. The process of claim 174, further comprising determining at least one
property of the
deasphalted bitumen and/or at least one property of the partially upgraded
bitumen
product, and adjusting at least one operating parameter of the thermal
treatment and/or
or the in situ bitumen recovery operation based on the at least one determined
property.
176. The process of claim 174 or 175, wherein all of the precipitated
asphaltene material
is left within the subsurface formation and the production fluid contains
substantially
none of the precipitated asphaltene material.
177. The process of any one of claims 174 to 176, wherein introducing the
asphaltene-
precipitating solvent into the subsurface formation comprises injecting the
asphaltene-
precipitating solvent via a horizontal injection well provided in the
subsurface
formation; and wherein the production fluid is recovered via a horizontal
production
well that is located below the horizontal injection well.
178. The process of claim 177, wherein horizontal production well and the
horizontal
injection well are operated according to gravity dominated recovery.
179. The process of any one of claims 174 to 178, wherein the asphaltene-
precipitating
solvent comprises an alkane solvent.
180. The process of claim 179, wherein the alkane solvent comprises propane,
butane,
pentane, hexane, heptane or a mixture thereof.
181. The process of claim 180, wherein the alkane solvent comprises propane.
182. The process of claim 180, wherein the alkane solvent comprises butane.
183. The process of claim 180, wherein the alkane solvent comprises pentane.
184. The process of any one of claims 174 to 183, wherein the thermal
treatment is
operated at a temperature above 200 C.
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185. The process of any one of claims 174 to 183, wherein the thermal
treatment is
operated at a temperature above 250 C.
186. The process of any one of claims 174 to 183, wherein the thermal
treatment is
operated at a temperature above 300 C.
187. The process of any one of claims 174 to 183, wherein the thermal
treatment is
operated at a temperature above 350 C.
188. The process of any one of claims 174 to 183, wherein the thermal
treatment is
operated at a temperature above 400 C.
189. The process of any one of claims 174 to 183, wherein the thermal
treatment is
operated at a temperature above 450 C.
190. The process of any one of claims 174 to 183, wherein the thermal
treatment is
operated at a temperature between 350 C and 450 C.
191. The process of any one of claims 174 to 190, wherein the thermal
treatment is
operated at a residence time of up to 300 minutes.
192. The process of any one of claims 174 to 190, wherein the thermal
treatment is
operated at a residence time below 60 minutes.
193. The process of any one of claims 174 to 190, wherein the thermal
treatment is
operated at a residence time below 15 minutes.
194. The process of any one of claims 174 to 190, wherein the thermal
treatment is
operated at a residence time between 5 minutes and 60 minutes.
195. The process of any one of claims 174 to 190, wherein the thermal
treatment is
operated at a residence time above 5 minutes.
196. The process of claim 191, wherein the residence time of the thermal
treatment is
above 15 minutes.
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197. The process of claim 191, wherein the residence time of the thermal
treatment is
above 60 minutes.
198. The process of claim 191, wherein the residence time of the thermal
treatment is
above 90 minutes.
199. The process of claim 191, wherein the residence time of the thermal
treatment is
above 150 minutes.
200. The process of claim 191, wherein the residence time of the thermal
treatment is
above 180 minutes.
201. The process of claim 191, wherein the residence time of the thermal
treatment is
above 210 minutes.
202. The process of any one of claims 174 to 201, wherein the thermal
treatment is
operated at a pressure between 50 psig and 1500 psig.
203. The process of any one of claims 174 to 201, wherein the thermal
treatment is
operated at a pressure between 50 psig and 1000 psig.
204. The process of any one of claims 174 to 203, wherein separating the
deasphalted
bitumen from the production fluid comprises removing water and solids from the
production fluid.
205. The process of any one of claims 174 to 204, wherein separating the
deasphalted
bitumen from the production fluid comprises recovering at least a portion of
the
asphaltene-precipitating solvent from the production fluid to obtain a
recovered
asphaltene-precipitating solvent for reintroduction into the subsurface
formation.
206. The process of any one of claims 174 to 205, wherein introducing the
asphaltene-
precipitating solvent into the subsurface formation comprises vaporizing the
asphaltene-precipitating solvent at surface, and injecting the asphaltene-
precipitating
solvent into the subsurface formation in vapor phase.
207. The process of any one of claims 174 to 206, wherein conditions of the in
situ bitumen
recovery operation comprise providing a solvent-to-bitumen ratio of the
mobilized fluid
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83
that is sufficiently high to cause the in situ precipitation of asphaltenes at
operating
extraction temperatures and pressures.
208. The process of claim 207, wherein the solvent-to-bitumen ratio of the
mobilized fluid
is sufficiently high to cause substantially all of the asphaltenes to
precipitate such that
the deasphalted bitumen fraction is fully deasphalted.
209. The process of claim 207, wherein the solvent-to-bitumen ratio of the
mobilized fluid
is provided to cause partial precipitation of asphaltenes such that the
deasphalted
bitumen fraction comprises a reduced asphaltene content.
210. The process of any one of claims 174 to 209, further comprising combining
the
deasphalted bitumen with a second hydrocarbon material to obtain a combined
deasphalted bitumen material that is subjected to the thermal treatment.
211. The process of claim 210, wherein the second hydrocarbon material
comprises a
second deasphalted bitumen.
212. The process of claim 210 or 211, wherein the second deasphalted bitumen
is
obtained from a second subsurface formation.
213. The process of any one of claims 210 to 212, wherein the deasphalted
bitumen and
the second hydrocarbon material are combined in relative proportions so that
the
combined deasphalted bitumen material has a predetermined composition based on
desired operating parameters of the thermal treatment.
214. The process of any one of claims 174 to 209, further comprising combining
multiple
production fluids respectively obtained from a plurality of in situ recovery
wells to form
a combined production fluid, and separating the deasphalted bitumen from the
combined production fluid.
215. The process of any one of claims 174 to 214, wherein subjecting the
deasphalted
bitumen to the thermal treatment comprises maintaining the deasphalted bitumen
in
liquid phase during the thermal treatment.
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216. The process of claim 215, wherein maintaining the deasphalted bitumen in
liquid
phase comprises providing conditions to cause a transfer of hydrogen from the
heavy
fraction to the light fraction directly in the liquid phase.
217. The process of any one of claims 174 to 216, wherein the thermal
treatment
comprises supplying the deasphalted bitumen to a thermal treatment vessel and
withdrawing the partially upgraded bitumen product from the thermal treatment
vessel
as a single stream from a product outlet.
218. The process of claim 217, wherein the thermal treatment comprises feeding
the
single stream of partially upgraded bitumen product to a gas separator and
removing
at least a portion of a gas phase from the partially upgraded bitumen product.
219. The process of any one of claims 174 to 218, wherein subjecting the
deasphalted
bitumen to the thermal treatment comprises adding an external source of
hydrogen to
the deasphalted bitumen.
220. The process of claim 219, wherein the external source of hydrogen is a
diatomic
hydrogen-containing gas.
221. The process of any one of claims 174 to 220, wherein subjecting the
deasphalted
bitumen to the thermal treatment comprises adding a hydrogen transfer agent to
the
deasphalted bitumen.
222. The process of claim 221, wherein the hydrogen transfer agent comprises
paraffins,
naphthenes, naphtheno-aromatics and/or aromatics.
223. The process of claim 221, wherein the hydrogen transfer agent comprises
at least
one of butane, propane, methane, tetralin, decalin, and anthracene.
224. The process of claims 221, wherein the hydrogen transfer agent comprises
a
hydrogen donor.
225. The process of claim 224, wherein the hydrogen donor comprises at least
one of
tetralin, decalin, synthetic crude oil, fractions of synthetic crude oil,
tight oil, shale oil
and light crude oils.
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226. The process of any one of claims 174 to 225, further comprising diluting
the partially
upgraded bitumen product with a diluent to obtain a diluted bitumen product.
227. The process of claim 226, wherein the diluent comprises an aromatic
diluent, a
naphthenic diluent, natural gas condensates, synthetic crude, a fraction of
synthetic
crude oil or streams thereof.
228. The process of claim 226 or 227, wherein the diluted bitumen product is
diluted to a
predetermined pipeline specification, and is also based on the determined
property of
the partially upgraded bitumen product.
229. The process of any one of claims 174 to 228, further comprising
recovering heat from
the partially upgraded bitumen product and reusing at least a portion of the
recovered
heat in the in situ bitumen recovery operation.
230. The process of claim 229, wherein the heat is at least partly reused for
pre-heating a
process stream that is part of the in situ bitumen recovery operation prior to
a unit
operation.
231. The process of any one of claims 174 to 230, wherein the deasphalted
bitumen has
a variable composition over time.
232. The process of claim 231, wherein the deasphalted bitumen has a higher
asphaltene
content during an earlier stage of the in situ bitumen recovery operation, and
a lower
asphaltene content during a later stage of the in situ bitumen recovery
operation.
233. The process of claim 232, wherein the earlier stage comprises a startup
stage, and
the later stage comprises a normal operation stage of the in situ bitumen
recovery
operation.
234. The process of any one of claims 223 to 233, further comprising
controlling the in situ
bitumen recovery operation or the thermal treatment or a combination thereof,
based
on the variable composition of the deasphalted bitumen.
235. The process of claim 234, wherein the thermal treatment is operated at
lower severity
conditions when the deasphalted bitumen has a higher asphaltene content, and
is
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86
operated at higher severity conditions when the deasphalted bitumen has a
lower
asphaltene content.
236. The process of claim 235, wherein the thermal treatment is continuously
controlled
based on the variable composition of the deasphalted bitumen.
237. The process of claim 235, wherein the thermal treatment is intermittently
controlled
based on the variable composition of the deasphalted bitumen.
238. A system for producing a partially upgraded bitumen product, the system
comprising:
an in situ bitumen recovery facility, comprising:
a horizontal injection well located in a subsurface formation and configured
for injecting an asphaltene-precipitating solvent into the subsurface
formation to contact bitumen contained therein at conditions to cause in situ
precipitation of at least a portion of asphaltenes within the subsurface
formation to produce a precipitated asphaltene material and a mobilized
fluid comprising a deasphalted bitumen fraction;
a horizontal production well located in the subsurface formation below the
horizontal injection well, thereby forming a well pair, the horizontal
production well being configured to recover the mobilized fluid to surface
as a production fluid that comprises the deasphalted bitumen fraction,
water, solids and a portion of the asphaltene-precipitating solvent while
leaving a majority of the precipitated asphaltene material within the
subsurface formation; and
a surface separation unit in fluid communication with the horizontal
production well and configured to separate deasphalted bitumen from the
production fluid; and
a thermal treatment facility in fluid communication with the in situ bitumen
recovery facility, and configured to subject the deasphalted bitumen to
thermal
treatment at about or below incipient coking conditions to produce the
partially
upgraded bitumen product.
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239. The system of claim 238, further comprising a measurement unit configured
to
determine at least one property of the deasphalted bitumen and/or at least one
property of the partially upgraded bitumen product, and a control unit
configured to
receive information from the measurement unit and to adjust at least one
operating
parameter of the thermal treatment facility and/or or the in situ bitumen
recovery facility
based on the at least one determined property.
240. The system of claim 238 or 239, wherein the horizontal production well
and the
horizontal injection well are configured as a well pair for gravity dominated
recovery.
241. The system of any one of claims 238 to 240, wherein the asphaltene-
precipitating
solvent comprises an alkane solvent.
242. The system of claim 241, wherein the alkane solvent comprises propane,
butane,
pentane, hexane, heptane or a mixture thereof.
243. The system of claim 242, wherein the alkane solvent comprises propane.
244. The system of claim 242, wherein the alkane solvent comprises butane.
245. The system of claim 242, wherein the alkane solvent comprises pentane.
246. The system of any one of claims 238 to 245, wherein the thermal treatment
facility
comprises a thermal treatment vessel configured to receive and thermally treat
the
deasphalted bitumen.
247. The system of claim 246, wherein the thermal treatment vessel is
configured to
operate at a temperature above 200 C.
248. The system of claim 246, wherein the thermal treatment vessel is
configured to
operate at a temperature above 250 C.
249. The system of claim 246, wherein the thermal treatment vessel is
configured to
operate at a temperature above 300 C.
250. The system of claim 246, wherein the thermal treatment vessel is
configured to
operate at a temperature above 350 C.
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251. The system of claim 246, wherein the thermal treatment vessel is
configured to
operate at a temperature above 400 C.
252. The system of claim 246, wherein the thermal treatment vessel is
configured to
operate at a temperature above 450 C.
253. The system of claim 246, wherein the thermal treatment vessel is
configured to
operate at a temperature between 350 C and 450 C.
254. The system of any one of claims 238 to 253, wherein the thermal treatment
vessel is
configured to operate at a residence time of up to 300 minutes.
255. The system of any one of claims 238 to 253, wherein the thermal treatment
vessel is
configured to operate at a residence time below 60 minutes.
256. The system of any one of claims 238 to 253, wherein the thermal treatment
vessel is
configured to operate at a residence time below 15 minutes.
257. The system of any one of claims 238 to 253, wherein the thermal treatment
vessel is
configured to operate at a residence time between 5 minutes and 60 minutes.
258. The system of any one of claims 238 to 253, wherein the thermal treatment
vessel is
configured to operate at a residence time above 5 minutes.
259. The system of claim 254, wherein the residence time of the thermal
treatment vessel
is above 15 minutes.
260. The system of claim 254, wherein the residence time of the thermal
treatment vessel
is above 60 minutes.
261. The system of claim 254, wherein the residence time of the thermal
treatment vessel
is above 90 minutes.
262. The system of claim 254, wherein the residence time of the thermal
treatment vessel
is above 150 minutes.
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263. The system of claim 254, wherein the residence time of the thermal
treatment vessel
is above 180 minutes.
264. The system of claim 254, wherein the residence time of the thermal
treatment vessel
is above 210 minutes.
265. The system of any one of claims 238 to 264, wherein the thermal treatment
vessel is
configured to operate at a pressure between 50 psig and 1500 psig.
266. The system of any one of claims 238 to 264, wherein the thermal treatment
vessel is
configured to operate at a pressure between 50 psig and 1000 psig.
267. The system of any one of claims 238 to 266, wherein the surface
separation unit is
further configured to separate water and solids from the production fluid.
268. The system of any one of claims 238 to 267, wherein the surface
separation unit is
further configured to recover at least a portion of the asphaltene-
precipitating solvent
from the production fluid to obtain a recovered asphaltene-precipitating
solvent for
reintroduction into the subsurface formation via the horizontal injection
well.
269. The system of any one of claims 238 to 268, wherein the in situ bitumen
recovery
facility comprises a vaporization unit configured to vaporize the asphaltene-
precipitating solvent at surface prior to supplying to the horizontal
injection well for
introduction as a vapor phase.
270. The system of any one of claims 238 to 269, wherein the thermal treatment
facility is
configured such that the deasphalted bitumen is maintained in liquid phase
during the
thermal treatment to cause a transfer of hydrogen from the heavy fraction to
the light
fraction directly in the liquid phase.
271. The system of any one of claims 238 to 270, wherein the thermal treatment
vessel
has a single product outlet for withdrawing the partially upgraded bitumen
product from
the thermal treatment vessel as a single stream.
272. The system of claim 271, wherein the thermal treatment facility further
comprises a
gas separator configured to receive the single stream of partially upgraded
bitumen
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product and remove at least a portion of a gas phase from the partially
upgraded
bitumen product.
273. The system of any one of claims 238 to 272, wherein the thermal treatment
facility
comprises no external hydrogen addition unit.
274. The system of any one of claims 238 to 272, wherein the thermal treatment
facility
comprises an external hydrogen addition unit configured to add an external
source of
hydrogen to the deasphalted bitumen.
275. The system of any one of claims 238 to 272, wherein the thermal treatment
facility
comprises an external hydrogen addition unit configured to add a hydrogen
transfer
agent to the deasphalted bitumen.
276. The system of any one of claims 238 to 275, further comprising a dilution
unit
configured to receive the partially upgraded bitumen product from the thermal
treatment facility and to dilute the partially upgraded bitumen product with a
diluent to
obtain a diluted bitumen product.
277. The system of any one of claims 238 to 276, further comprising a heat
recovery unit
configured to recover heat from the thermal treatment facility and to reuse at
least a
portion of the recovered heat in the in situ bitumen recovery facility.
278. The system of claim 277, wherein the heat is recovered from the partially
upgraded
bitumen product.
279. The system of claim 277 or 278, wherein the heat is at least partly
reused for pre-
heating a process stream of the in situ bitumen recovery facility prior to a
unit operation.
280. The system of any one of claims 238 to 279, wherein the deasphalted
bitumen has a
variable composition over time.
281. The system of claim 280, wherein the deasphalted bitumen has a higher
asphaltene
content during an earlier stage of operating the in situ bitumen recovery
facility, and a
lower asphaltene content during a later stage of operating the in situ bitumen
recovery
facility.
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282. The system of claim 281, wherein the earlier stage comprises a startup
stage, and
the later stage comprises a normal operation stage of the in situ bitumen
recovery
facility.
283. The system of any one of claims 280 to 282, further comprising a control
system
configured to control the in situ bitumen recovery facility or the thermal
treatment or a
combination thereof, based on the variable composition of the deasphalted
bitumen.
284. The system of claim 283, wherein the control system is configured to
control
operation of the thermal treatment facility at lower severity conditions when
the
deasphalted bitumen has a higher asphaltene content, and at higher severity
conditions when the deasphalted bitumen has a lower asphaltene content.
285. The system of claim 283, wherein the control system is configured to
continuously
control the thermal treatment facility based on the variable composition of
the
deasphalted bitumen.
286. The system of claim 283, wherein the control system is configured to
intermittently
control the thermal treatment facility based on the variable composition of
the
deasphalted bitumen.
Date Recue/Date Received 2021-04-23

Description

1
PARTIAL UPGRADING OF BITUMEN WITH SUBSURFACE SOLVENT
DEASPHALTING AND AT-SURFACE THERMAL TREATMENT
TECHNICAL FIELD
[1] The technical field generally relates to the treatment of bitumen, and
more particularly
to the partial upgrading of bitumen using subsurface solvent deasphalting
followed by at-
surface thermal treatment.
BACKGROUND
[2] Bitumen generally has a high viscosity, which can make pipeline
transportation and
processing of bitumen difficult. Various methods exist to upgrade bitumen and
increase its
suitability for pipeline transportation, although such methods have various
drawbacks.
[3] For instance, bitumen upgrader facilities of various designs can upgrade
the bitumen
to produce a bitumen product having desirable physicochemical characteristics
for
pipelinability. However, conventional upgrader facilities have high associated
capital and
operating costs. In addition, at-surface deasphalting processes necessitate
the handling
and treatment of precipitated asphaltenes and can also lead to lower yields,
which can
result in higher operating costs and reduced revenue. Furthermore, in some
conventional
upgrading methods, such as severe thermal cracking, hydrogen originally
present in the
bitumen is lost to the gas phase such that, in the absence of added hydrogen,
significant
and undesirable olefin production can occur. In order to meet pipeline
specifications, the
olefin content of the bitumen should be minimized, typically to less than 1
wt% (1-decene
equivalent). Thus, upgrading methods that produce bitumen products having a
high olefin
content typically use an external source of hydrogen, via some form of
hydroprocessing.
The hydroprocessing can facilitate compensating for at least some of the
bitumen
hydrogen losses that occurred during cracking, saturating or converting the
olefins by
breaking down the carbon-to-carbon double bonds and converting them to single
bonds,
and stabilizing cracked products to achieve targeted bitumen quality
requirements.
Hydroprocessing can include the addition of hydrogen in a separate unit, for
example.
However, for economic and technical reasons, various traditional
hydroprocessing
methods are generally avoided since external hydrogen production has high
associated
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costs. Indeed, any approach using external hydrogen is likely to have higher
capital and
operating costs.
[4] Another option to improve bitumen viscosity is to dilute the bitumen, for
example with
naphtha or natural gas condensate as a diluent. This diluted bitumen is often
referred to
as "dilbit". While bitumen dilution does not have the same capital cost
penalty as a bitumen
upgrader facility, it still can have high associated operating costs. For
example, since dilbit
includes a significant volume of diluent (e.g., one third diluent and two
thirds bitumen per
barrel of diluted bitumen), significant pipeline capacity is therefore taken
up by the diluent
for pipelining of the dilbit as well as the return pipelining of separated
diluent to be reused
in bitumen dilution. Thus, since diluent often travels to and from the bitumen
recovery
operation, approximately a third of the pipeline capacity can be required for
diluent
transport and approximately a third of the hydrocarbon inventory can be
diluent, which is
costly and inefficient.
[5] Other bitumen upgrading methods can involve high severity operating
conditions,
significant coking, and/or hydrocracking, which can also involve technical
challenges as
well as high capital and operating costs.
[6] Various challenges exist in terms of technologies for bitumen upgrading
and viscosity
reduction.
SUMMARY
[7] In accordance with a first aspect, there is provided a process for
producing a partially
upgraded bitumen product. The process comprises an in situ bitumen recovery
operation
comprising: introducing an asphaltene-precipitating solvent into a subsurface
formation to
contact bitumen contained in the subsurface formation, the bitumen comprising
a light
fraction and a heavy fraction comprising asphaltenes; inducing in situ
precipitation of at
least a portion of the asphaltenes within the subsurface formation to produce
a precipitated
asphaltene material and a mobilized fluid comprising a deasphalted bitumen
fraction;
recovering the mobilized fluid as a production fluid comprising the
deasphalted bitumen
fraction, water, solids and a portion of the asphaltene-precipitating solvent
while leaving a
majority of the precipitated asphaltene material within the subsurface
formation;
separating deasphalted bitumen from the production fluid; determining a
property of the
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deasphalted bitumen; and subjecting the deasphalted bitumen to a thermal
treatment at
about or below incipient coking conditions to produce the partially upgraded
bitumen
product, wherein the thermal treatment comprises adjusting an operating
parameter of the
thermal treatment based on the property of the deasphalted bitumen stream.
[8] According to a possible implementation, all of the precipitated asphaltene
material is
left within the subsurface formation and the production fluid contains
substantially none of
the precipitated asphaltene material.
[9] According to a possible implementation, introducing the asphaltene-
precipitating
solvent into the subsurface formation comprises injecting the asphaltene-
precipitating
solvent via a horizontal injection well provided in the subsurface formation;
and wherein
the production fluid is recovered via a horizontal production well that is
located below the
horizontal injection well.
[10] According to a possible implementation, the asphaltene-precipitating
solvent
comprises an alkane solvent.
[11] According to a possible implementation, the alkane solvent comprises
propane,
butane, pentane, hexane, heptane or a mixture thereof.
[12] According to a possible implementation, the alkane solvent comprises
propane.
[13] According to a possible implementation, the alkane solvent comprises
butane.
[14] According to a possible implementation, the alkane solvent comprises
pentane.
[15] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises heating the deasphalted bitumen to a temperature
between
200 C and 475 C.
[16] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises heating the deasphalted bitumen to a temperature
between
350 C and 450 C.
[17] According to a possible implementation, the thermal treatment is
performed for a
duration of up to 300 minutes.
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[18] According to a possible implementation, the thermal treatment is
performed for a
duration of between 15 minutes and 240 minutes.
[19] According to a possible implementation, the thermal treatment is
performed at a
pressure between 50 psig and 1500 psig.
[20] According to a possible implementation, the thermal treatment is
performed at a
pressure between 50 psig and 1000 psig.
[21] According to a possible implementation, separating the deasphalted
bitumen from the
production fluid comprises removing water and solids from the production
fluid.
[22] According to a possible implementation, separating deasphalted bitumen
from the
production fluid comprises recovering at least a portion of the asphaltene-
precipitating
solvent from the production fluid to obtain a recovered asphaltene-
precipitating solvent for
reintroduction into the subsurface formation.
[23] According to a possible implementation, introducing the asphaltene-
precipitating
solvent into the subsurface formation comprises vaporizing the asphaltene-
precipitating
solvent and injecting the asphaltene-precipitating solvent into the subsurface
formation in
vapor phase.
[24] According to a possible implementation, conditions of the in situ bitumen
recovery
operation comprise providing a solvent-to-bitumen ratio of the mobilized fluid
that is
sufficiently high to cause the in situ precipitation of asphaltenes at
operating extraction
temperatures and pressures.
[25] According to a possible implementation, the solvent-to-bitumen ratio of
the mobilized
fluid is sufficiently high to cause substantially all of the asphaltenes to
precipitate such that
the deasphalted bitumen fraction is fully deasphalted.
[26] According to a possible implementation, the solvent-to-bitumen ratio of
the mobilized
fluid is provided to cause partial precipitation of asphaltenes such that the
deasphalted
bitumen fraction comprises a reduced asphaltene content.
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[27] According to a possible implementation, the property of the deasphalted
bitumen
comprises at least one of asphaltene content of the deasphalted bitumen, a
compositional
characteristic of the deasphalted bitumen, a viscosity of the deasphalted
bitumen and a
density of the deasphalted bitumen.
[28] According to a possible implementation, the process further comprises
combining the
deasphalted bitumen with a second hydrocarbon material to obtain a combined
deasphalted bitumen material that is subjected to the thermal treatment.
[29] According to a possible implementation, combining the deasphalted bitumen
with the
second hydrocarbon material to obtain the combined deasphalted bitumen
material is
performed when the property of the deasphalted bitumen is above or below a
given
threshold.
[30] According to a possible implementation, the second hydrocarbon material
comprises
a second deasphalted bitumen.
[31] According to a possible implementation, the second deasphalted bitumen is
obtained
from a second subsurface formation.
[32] According to a possible implementation, the process further comprises
subjecting the
deasphalted bitumen to an at-surface deasphalting treatment to further reduce
the
asphaltene content of the deasphalted bitumen prior to the thermal treatment.
[33] According to a possible implementation, the at-surface deasphalting
treatment
comprises using at least a portion of the recovered asphaltene-precipitating
solvent as
deasphalting solvent.
[34] According to a possible implementation, the deasphalted bitumen and the
second
hydrocarbon material are combined in relative proportions so that the combined
deasphalted bitumen material has a predetermined composition based on desired
operating parameters of the thermal treatment.
[35] According to a possible implementation, the process further comprises
combining
multiple production fluids respectively obtained from a plurality of in situ
recovery wells to
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form a combined production fluid, and separating the deasphalted bitumen from
the
combined production fluid.
[36] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises maintaining the deasphalted bitumen in liquid
phase during
the thermal treatment.
[37] According to a possible implementation, maintaining the deasphalted
bitumen in
liquid phase comprises providing conditions to cause a transfer of hydrogen
from the
heavy fraction to the light fraction directly in the liquid phase.
[38] According to a possible implementation, the thermal treatment comprises
supplying
the deasphalted bitumen to a thermal treatment vessel and withdrawing the
partially
upgraded bitumen product from the thermal treatment vessel as a single stream
from a
product outlet.
[39] According to a possible implementation, the thermal treatment comprises
feeding the
single stream of partially upgraded bitumen product to a gas separator and
removing at
least a portion of a gas phase from the partially upgraded bitumen product.
[40] According to a possible implementation, adjusting the operating parameter
of the
thermal treatment in accordance with the property of the deasphalted bitumen
comprises
adjusting at least one of temperature, duration and pressure of the thermal
treatment.
[41] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises adding an external source of hydrogen to the
deasphalted
bitumen.
[42] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises adding a hydrogen transfer agent to the
deasphalted
bitumen.
[43] According to a possible implementation, the external source of hydrogen
is a diatomic
hydrogen-containing gas.
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[44] According to a possible implementation, the hydrogen transfer agent
comprises
paraffins, naphthenes, naphtheno-aromatics and/or aromatics.
[45] According to a possible implementation, the hydrogen transfer agent
comprises at
least one of butane, propane, methane, tetralin, decalin, and anthracene.
[46] According to a possible implementation, the hydrogen transfer agent
comprises a
hydrogen donor.
[47] According to a possible implementation, the hydrogen donor comprises at
least one
of tetralin, decalin, synthetic crude oil, fractions of synthetic crude oil,
tight oil, shale oil
and light crude oils.
[48] According to a possible implementation, the process further comprises
diluting the
partially upgraded bitumen product with a diluent to obtain a diluted bitumen
product.
[49] According to a possible implementation, the diluent comprises an aromatic
diluent, a
naphthenic diluent, natural gas condensates, synthetic crude, a fraction of
synthetic crude
oil or combinations thereof.
[50] According to a possible implementation, the diluted bitumen product is
diluted to a
predetermined pipeline specification, and is also based on the determined
property of the
partially upgraded bitumen product.
[51] According to a possible implementation, the process further comprises
recovering
heat from the partially upgraded bitumen product and reusing at least a
portion of the
recovered heat in the in situ bitumen recovery operation.
[52] According to a possible implementation, the heat is at least partly
reused for pre-
heating a process stream that is part of the in situ bitumen recovery
operation prior to a
unit operation.
[53] According to a possible implementation, the deasphalted bitumen has a
variable
composition over time.
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[54] According to a possible implementation, the deasphalted bitumen has a
higher
asphaltene content during an earlier stage of the in situ bitumen recovery
operation, and
a lower asphaltene content during a later stage of the in situ bitumen
recovery operation.
[55] According to a possible implementation, the earlier stage comprises a
startup stage,
and the later stage comprises a normal operation stage of the in situ bitumen
recovery
operation.
[56] According to a possible implementation, the process further comprises
controlling the
in situ bitumen recovery operation or the thermal treatment or a combination
thereof,
based on the variable composition of the deasphalted bitumen.
[57] According to a possible implementation, the thermal treatment is operated
at lower
severity conditions when the deasphalted bitumen has a higher asphaltene
content, and
is operated at higher severity conditions when the deasphalted bitumen has a
lower
asphaltene content.
[58] According to a possible implementation, the thermal treatment is
continuously
controlled based on the variable composition of the deasphalted bitumen.
[59] According to a possible implementation, the thermal treatment is
intermittently
controlled based on the variable composition of the deasphalted bitumen.
[60] In accordance with another aspect, there is provided a process for
producing a
partially upgraded bitumen product. The process comprises recovering a
mobilized
subsurface fluid as production fluid comprising a deasphalted bitumen fraction
as part of
an in situ bitumen recovery operation, comprising: introducing an asphaltene-
precipitating
solvent into a subsurface formation to contact bitumen contained in the
subsurface
formation, the bitumen comprising a light fraction and a heavy fraction
comprising
asphaltenes; inducing in situ precipitation of at least a portion of the
asphaltenes within
the subsurface formation to produce a precipitated asphaltene material and the
mobilized
subsurface fluid comprising the deasphalted bitumen fraction; and producing
the mobilized
subsurface fluid to the surface as the production fluid that includes the
deasphalted
bitumen fraction, water, solids and a portion of the asphaltene-precipitating
solvent while
leaving a majority of the precipitated asphaltene material within the
subsurface formation;
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separating deasphalted bitumen from the production fluid; determining a
property of the
deasphalted bitumen; adjusting a variable related to the in situ bitumen
recovery operation
based on the property of the deasphalted bitumen to obtain a deasphalted
bitumen
feedstock; and subjecting the deasphalted bitumen feedstock to a thermal
treatment at
about or below incipient coking conditions to produce the partially upgraded
bitumen
product.
[61] According to a possible implementation, all of the precipitated
asphaltene material is
left within the subsurface formation and the production fluid contains
substantially none of
the precipitated asphaltene material.
[62] According to a possible implementation, introducing the asphaltene-
precipitating
solvent into the subsurface formation comprises injecting the asphaltene-
precipitating
solvent via a horizontal injection well provided in the subsurface formation;
and wherein
the production fluid is recovered via a horizontal production well that is
located below the
horizontal injection well.
[63] According to a possible implementation, the asphaltene-precipitating
solvent
comprises an alkane solvent.
[64] According to a possible implementation, the alkane solvent comprises
propane,
butane, pentane, hexane, heptane or a mixture thereof.
[65] According to a possible implementation, the alkane solvent comprises
propane.
[66] According to a possible implementation, the alkane solvent comprises
butane.
[67] According to a possible implementation, the alkane solvent comprises
pentane.
[68] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises heating the deasphalted bitumen to a temperature
between
200 C and 475 C.
[69] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises heating the deasphalted bitumen to a temperature
between
350 C and 450 C.
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[70] According to a possible implementation, the thermal treatment is
performed for a
duration of up to 300 minutes.
[71] According to a possible implementation, the thermal treatment is
performed for a
duration of between 15 minutes and 240 minutes.
[72] According to a possible implementation, the thermal treatment is
performed at a
pressure between 50 psig and 1500 psig.
[73] According to a possible implementation, the thermal treatment is
performed at a
pressure between 50 psig and 1000 psig.
[74] According to a possible implementation, separating deasphalted bitumen
from the
production fluid comprises removing water and solids from the production
fluid.
[75] According to a possible implementation, separating deasphalted bitumen
from the
production fluid comprises recovering at least a portion of the asphaltene-
precipitating
solvent from the production fluid to obtain a recovered asphaltene-
precipitating solvent for
reintroduction into the subsurface formation.
[76] According to a possible implementation, introducing the asphaltene-
precipitating
solvent into the subsurface formation comprises vaporizing the asphaltene-
precipitating
solvent at surface, and injecting the asphaltene-precipitating solvent into
the subsurface
formation in vapor phase.
[77] According to a possible implementation, conditions of the in situ bitumen
recovery
operation comprise providing a solvent-to-bitumen ratio of the mobilized fluid
that is
sufficiently high to cause the in situ precipitation of asphaltenes at
operating extraction
temperatures and pressures.
[78] According to a possible implementation, the solvent-to-bitumen ratio of
the mobilized
fluid is sufficiently high to cause substantially all of the asphaltenes to
precipitate such that
the deasphalted bitumen fraction is fully deasphalted.
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[79] According to a possible implementation, the solvent-to-bitumen ratio of
the mobilized
fluid is provided to cause partial precipitation of asphaltenes such that the
deasphalted
bitumen fraction comprises a reduced asphaltene content.
[80] According to a possible implementation, adjusting the variable related to
the in situ
bitumen recovery operation comprises adjusting at least one operating
parameter related
thereto.
[81] According to a possible implementation, adjusting the operating parameter
of the in
situ bitumen recovery operation comprises at least one of modifying the type
or
composition of the asphaltene-precipitating solvent introduced into the
subsurface
formation, modifying an amount or rate of the asphaltene-precipitating solvent
introduced
into the subsurface formation, adjusting a solvent-to-bitumen ratio within the
subsurface
formation or of the production fluid, adjusting a temperature of the
asphaltene-precipitating
solvent to be introduced in the subsurface formation, adjusting a temperature
within the
subsurface formation, and adjusting heat that is provided to the reservoir.
[82] According to a possible implementation, adjusting the variable related to
the in situ
bitumen recovery operation comprises adjusting at least one characteristic of
the
deasphalted bitumen.
[83] According to a possible implementation, the property of the deasphalted
bitumen
comprises at least one of asphaltene content of the deasphalted bitumen, a
compositional
characteristic of the deasphalted bitumen, a viscosity of the deasphalted
bitumen and a
density of the deasphalted bitumen.
[84] According to a possible implementation, the process further comprises
combining the
deasphalted bitumen with a second hydrocarbon material to obtain a combined
deasphalted bitumen material that is subjected to the thermal treatment.
[85] According to a possible implementation, combining the deasphalted bitumen
with the
second hydrocarbon material to obtain the combined deasphalted bitumen
material is
performed when the property of the deasphalted bitumen is above or below a
given
threshold.
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[86] According to a possible implementation, the second hydrocarbon material
comprises
a second deasphalted bitumen.
[87] According to a possible implementation, the second deasphalted bitumen is
obtained
from a second subsurface formation.
[88] According to a possible implementation, the process further comprises
subjecting the
deasphalted bitumen to an at-surface deasphalting treatment to further reduce
the
asphaltene content of the deasphalted bitumen prior to the thermal treatment.
[89] According to a possible implementation, the at-surface deasphalting
treatment
comprises using at least a portion of the recovered asphaltene-precipitating
solvent as
deasphalting solvent.
[90] According to a possible implementation, the deasphalted bitumen and the
second
hydrocarbon material are combined in relative proportions so that the combined
deasphalted bitumen material has a predetermined composition based on desired
operating parameters of the thermal treatment.
[91] According to a possible implementation, the process further comprises
combining
multiple production fluids respectively obtained from a plurality of in situ
recovery wells to
form a combined production fluid, and separating the deasphalted bitumen from
the
combined production fluid.
[92] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises maintaining the deasphalted bitumen in liquid
phase during
the thermal treatment.
[93] According to a possible implementation, maintaining the deasphalted
bitumen in
liquid phase comprises providing conditions to cause a transfer of hydrogen
from the
heavy fraction to the light fraction directly in the liquid phase.
[94] According to a possible implementation, the thermal treatment comprises
supplying
the deasphalted bitumen to a thermal treatment vessel and withdrawing the
partially
upgraded bitumen product from the thermal treatment vessel as a single stream
from a
product outlet.
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[95] According to a possible implementation, the thermal treatment comprises
feeding the
single stream of partially upgraded bitumen product to a gas separator and
removing at
least a portion of a gas phase from the partially upgraded bitumen product.
[96] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises adding an external source of hydrogen to the
deasphalted
bitumen.
[97] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises adding a hydrogen transfer agent to the
deasphalted
bitumen.
[98] According to a possible implementation, the external source of hydrogen
is a diatomic
hydrogen-containing gas.
[99] According to a possible implementation, the hydrogen transfer agent
comprises
paraffins, naphthenes, naphtheno-aromatics and/or aromatics.
[100] According to a possible implementation, the hydrogen transfer agent
comprises at
least one of butane, propane, methane, tetralin, decalin, and anthracene.
[101] According to a possible implementation, the hydrogen transfer agent
comprises a
hydrogen donor.
[102] According to a possible implementation, the hydrogen donor comprises at
least one
of tetralin, decalin, synthetic crude oil, fractions of synthetic crude oil,
tight oil, shale oil
and light crude oils.
[103] According to a possible implementation, the process further comprises
diluting the
partially upgraded bitumen product with a diluent to obtain a diluted bitumen
product.
[104] According to a possible implementation, the diluent comprises an
aromatic diluent,
a naphthenic diluent, natural gas condensates, synthetic crude, a fraction of
synthetic
crude oil or streams thereof.
[105] According to a possible implementation, the diluted bitumen product is
diluted to a
predetermined pipeline specification.
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[106] According to a possible implementation, the process further comprises
recovering
heat from the partially upgraded bitumen product and reusing at least a
portion of the
recovered heat in the in situ bitumen recovery operation.
[107] According to a possible implementation, the heat is at least partly
reused for pre-
heating a process stream that is part of the in situ bitumen recovery
operation prior to a
unit operation.
[108] According to a possible implementation, the deasphalted bitumen has a
variable
composition over time.
[109] According to a possible implementation, the deasphalted bitumen has a
higher
asphaltene content during an earlier stage of the in situ bitumen recovery
operation, and
a lower asphaltene content during a later stage of the in situ bitumen
recovery operation.
[110] According to a possible implementation, the earlier stage comprises a
startup stage,
and the later stage comprises a normal operation stage of the in situ bitumen
recovery
operation.
[111] According to a possible implementation, the process further comprises
controlling
the in situ bitumen recovery operation or the thermal treatment or a
combination thereof,
based on the variable composition of the deasphalted bitumen.
[112] According to a possible implementation, the thermal treatment is
operated at lower
severity conditions when the deasphalted bitumen has a higher asphaltene
content, and
is operated at higher severity conditions when the deasphalted bitumen has a
lower
asphaltene content.
[113] According to a possible implementation, the thermal treatment is
continuously
controlled based on the variable composition of the deasphalted bitumen.
[114] According to a possible implementation, the thermal treatment is
intermittently
controlled based on the variable composition of the deasphalted bitumen.
[115] According to another aspect, there is provided a process for producing a
partially
upgraded bitumen product. The process comprises an in situ bitumen recovery
process
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comprising: introducing an asphaltene-precipitating solvent into a subsurface
formation to
contact bitumen contained in the subsurface formation, the bitumen comprising
a light
fraction and a heavy fraction comprising asphaltenes; inducing in situ
precipitation of at
least a portion of the asphaltenes within the subsurface formation to produce
a precipitated
asphaltene material and a mobilized fluid comprising a deasphalted bitumen
fraction;
recovering the mobilized fluid as a production fluid comprising the
deasphalted bitumen
fraction, water, solids and a portion of the asphaltene-precipitating solvent
while leaving a
majority of the precipitated asphaltene material within the subsurface
formation;
separating deasphalted bitumen from the production fluid; subjecting the
deasphalted
bitumen to a thermal treatment at about or below incipient coking conditions
to produce
the partially upgraded bitumen product; determining a property of the
partially upgraded
bitumen product; and adjusting an operating parameter of the thermal treatment
based on
the determined property of the partially upgraded bitumen product.
[116] According to a possible implementation, all of the precipitated
asphaltene material
is left within the subsurface formation and the production fluid contains
substantially none
of the precipitated asphaltene material.
[117] According to a possible implementation, introducing the asphaltene-
precipitating
solvent into the subsurface formation comprises injecting the asphaltene-
precipitating
solvent via a horizontal injection well provided in the subsurface formation;
and wherein
the production fluid is recovered via a horizontal production well that is
located below the
horizontal injection well.
[118] According to a possible implementation, the asphaltene-precipitating
solvent
comprises an alkane solvent.
[119] According to a possible implementation, the alkane solvent comprises
propane,
butane, pentane, hexane, heptane or a mixture thereof.
[120] According to a possible implementation, the alkane solvent comprises
propane.
[121] According to a possible implementation, the alkane solvent comprises
butane.
[122] According to a possible implementation, the alkane solvent comprises
pentane.
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[123] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises heating the deasphalted bitumen to a temperature
between
200 C and 475 C.
[124] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises heating the deasphalted bitumen to a temperature
between
350 C and 450 C.
[125] According to a possible implementation, the thermal treatment is
performed for a
duration of up to 300 minutes.
[126] According to a possible implementation, the thermal treatment is
performed for a
duration of between 15 minutes and 240 minutes.
[127] According to a possible implementation, the thermal treatment is
performed at a
pressure between 50 psig and 1500 psig.
[128] According to a possible implementation, the thermal treatment is
performed at a
pressure between 50 psig and 1000 psig.
[129] According to a possible implementation, separating the deasphalted
bitumen from
the production fluid comprises removing water and solids from the production
fluid.
[130] According to a possible implementation, separating the deasphalted
bitumen from
the production fluid comprises recovering at least a portion of the asphaltene-
precipitating
solvent from the production fluid to obtain a recovered asphaltene-
precipitating solvent for
reintroduction into the subsurface formation.
[131] According to a possible implementation, introducing the asphaltene-
precipitating
solvent into the subsurface formation comprises vaporizing the asphaltene-
precipitating
solvent at surface, and injecting the asphaltene-precipitating solvent into
the subsurface
formation in vapor phase.
[132] According to a possible implementation, conditions of the in situ
bitumen recovery
operation comprise providing a solvent-to-bitumen ratio of the mobilized fluid
that is
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sufficiently high to cause the in situ precipitation of asphaltenes at
operating extraction
temperatures and pressures.
[133] According to a possible implementation, the solvent-to-bitumen ratio of
the mobilized
fluid is sufficiently high to cause substantially all of the asphaltenes to
precipitate such that
the deasphalted bitumen fraction is fully deasphalted.
[134] According to a possible implementation, the solvent-to-bitumen ratio of
the mobilized
fluid is provided to cause partial precipitation of asphaltenes such that the
deasphalted
bitumen fraction comprises a reduced asphaltene content.
[135] According to a possible implementation, the determined property of the
partially
upgraded bitumen product comprises at least one of asphaltene content of the
partially
upgraded bitumen product, a compositional characteristic of the partially
upgraded
bitumen product, a viscosity of the partially upgraded bitumen product, a
density of the
partially upgraded bitumen product, and an olefin content of the partially
upgraded bitumen
product.
[136] According to a possible implementation, the process further comprises
combining
the deasphalted bitumen with a second hydrocarbon material to obtain a
combined
deasphalted bitumen material that is subjected to the thermal treatment.
[137] According to a possible implementation, combining the deasphalted
bitumen with
the second hydrocarbon material to obtain the combined deasphalted bitumen
material is
performed when the property of the deasphalted bitumen is above or below a
given
threshold.
[138] According to a possible implementation, the second hydrocarbon material
comprises a second deasphalted bitumen.
[139] According to a possible implementation, the second deasphalted bitumen
is
obtained from a second subsurface formation.
[140] According to a possible implementation, the process further comprises
subjecting
the deasphalted bitumen to an at-surface deasphalting treatment to further
reduce the
asphaltene content of the deasphalted bitumen prior to the thermal treatment.
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[141] According to a possible implementation, the at-surface deasphalting
treatment
comprises using at least a portion of the recovered asphaltene-precipitating
solvent as
deasphalting solvent.
[142] According to a possible implementation, the deasphalted bitumen and the
second
hydrocarbon material are combined in relative proportions so that the combined
deasphalted bitumen material has a predetermined composition based on desired
operating parameters of the thermal treatment.
[143] According to a possible implementation, the process further comprises
combining
multiple production fluids respectively obtained from a plurality of in situ
recovery wells to
form a combined production fluid, and separating the deasphalted bitumen from
the
combined production fluid.
[144] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises maintaining the deasphalted bitumen in liquid
phase during
the thermal treatment.
[145] According to a possible implementation, maintaining the deasphalted
bitumen in
liquid phase comprises providing conditions to cause a transfer of hydrogen
from the
heavy fraction to the light fraction directly in the liquid phase.
[146] According to a possible implementation, the thermal treatment comprises
supplying
the deasphalted bitumen to a thermal treatment vessel and withdrawing the
partially
upgraded bitumen product from the thermal treatment vessel as a single stream
from a
product outlet.
[147] According to a possible implementation, the thermal treatment comprises
feeding
the single stream of partially upgraded bitumen product to a gas separator and
removing
at least a portion of a gas phase from the partially upgraded bitumen product.
[148] According to a possible implementation, adjusting the operating
parameter of the
thermal treatment based on the determined property of the partially upgraded
bitumen
product comprises adjusting at least one of the temperature, the duration and
the pressure
of the thermal treatment.
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[149] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises adding an external source of hydrogen to the
deasphalted
bitumen.
[150] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises adding a hydrogen transfer agent to the
deasphalted
bitumen.
[151] According to a possible implementation, the external source of hydrogen
is a
diatomic hydrogen-containing gas.
[152] According to a possible implementation, the hydrogen transfer agent
comprises
paraffins, naphthenes, naphtheno-aromatics and/or aromatics.
[153] According to a possible implementation, the hydrogen transfer agent
comprises at
least one of butane, propane, methane, tetralin, decalin, and anthracene.
[154] According to a possible implementation, the hydrogen transfer agent
comprises a
hydrogen donor.
[155] According to a possible implementation, the hydrogen donor comprises at
least one
of tetralin, decalin, synthetic crude oil, fractions of synthetic crude oil,
tight oil, shale oil
and light crude oils.
[156] According to a possible implementation, the process further comprises
diluting the
partially upgraded bitumen product with a diluent to obtain a diluted bitumen
product.
[157] According to a possible implementation, the diluent comprises an
aromatic diluent,
a naphthenic diluent, natural gas condensates, synthetic crude, a fraction of
synthetic
crude oil or streams thereof.
[158] According to a possible implementation, the diluted bitumen product is
diluted to a
predetermined pipeline specification, and is also based on the determined
property of the
partially upgraded bitumen product.
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[159] According to a possible implementation, the process further comprises
recovering
heat from the partially upgraded bitumen product and reusing at least a
portion of the
recovered heat in the in situ bitumen recovery operation.
[160] According to a possible implementation, the heat is at least partly
reused for pre-
heating a process stream that is part of the in situ bitumen recovery
operation prior to a
unit operation.
[161] According to a possible implementation, the deasphalted bitumen has a
variable
composition over time.
[162] According to a possible implementation, the deasphalted bitumen has a
higher
asphaltene content during an earlier stage of the in situ bitumen recovery
operation, and
a lower asphaltene content during a later stage of the in situ bitumen
recovery operation.
[163] According to a possible implementation, the earlier stage comprises a
startup stage,
and the later stage comprises a normal operation stage of the in situ bitumen
recovery
operation.
[164] According to a possible implementation, the process further comprises
controlling
the in situ bitumen recovery operation or the thermal treatment or a
combination thereof,
based on the variable composition of the deasphalted bitumen.
[165] According to a possible implementation, the thermal treatment is
operated at lower
severity conditions when the deasphalted bitumen has a higher asphaltene
content, and
is operated at higher severity conditions when the deasphalted bitumen has a
lower
asphaltene content.
[166] According to a possible implementation, the thermal treatment is
continuously
controlled based on the variable composition of the deasphalted bitumen.
[167] According to a possible implementation, the thermal treatment is
intermittently
controlled based on the variable composition of the deasphalted bitumen.
[168] In accordance with another aspect, there is provided a process for
producing a
partially upgraded bitumen product. The process comprises conducting an in
situ bitumen
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recovery operation, comprising: introducing an asphaltene-precipitating
solvent into a
subsurface formation to contact bitumen contained in the subsurface formation,
the
bitumen comprising a light fraction and a heavy fraction comprising
asphaltenes, at
conditions to cause in situ precipitation of at least a portion of the
asphaltenes within the
subsurface formation to produce a precipitated asphaltene material and a
mobilized fluid
comprising a deasphalted bitumen fraction; recovering the mobilized fluid as a
production
fluid comprising the deasphalted bitumen fraction, water, solids and a portion
of the
asphaltene-precipitating solvent while leaving a majority of the precipitated
asphaltene
material within the subsurface formation; and separating deasphalted bitumen
from the
production fluid; and subjecting the deasphalted bitumen to a thermal
treatment at about
or below incipient coking conditions to produce the partially upgraded bitumen
product.
[169] According to a possible implementation, the process further comprises
determining
at least one property of the deasphalted bitumen and/or at least one property
of the
partially upgraded bitumen product, and adjusting at least one operating
parameter of the
thermal treatment and/or or the in situ bitumen recovery operation based on
the at least
one determined property.
[170] According to a possible implementation, all of the precipitated
asphaltene material
is left within the subsurface formation and the production fluid contains
substantially none
of the precipitated asphaltene material.
[171] According to a possible implementation, introducing the asphaltene-
precipitating
solvent into the subsurface formation comprises injecting the asphaltene-
precipitating
solvent via a horizontal injection well provided in the subsurface formation;
and wherein
the production fluid is recovered via a horizontal production well that is
located below the
horizontal injection well.
[172] According to a possible implementation, horizontal production well and
the
horizontal injection well are operated according to gravity dominated
recovery.
[173] According to a possible implementation, the asphaltene-precipitating
solvent
comprises an alkane solvent.
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[174] According to a possible implementation, the alkane solvent comprises
propane,
butane, pentane, hexane, heptane or a mixture thereof.
[175] According to a possible implementation, the alkane solvent comprises
propane.
[176] According to a possible implementation, the alkane solvent comprises
butane.
[177] According to a possible implementation, the alkane solvent comprises
pentane.
[178] According to a possible implementation, the thermal treatment is
operated at a
temperature above 200 C.
[179] According to a possible implementation, the thermal treatment is
operated at a
temperature above 250 C.
[180] According to a possible implementation, the thermal treatment is
operated at a
temperature above 300 C.
[181] According to a possible implementation, the thermal treatment is
operated at a
temperature above 350 C.
[182] According to a possible implementation, the thermal treatment is
operated at a
temperature above 400 C.
[183] According to a possible implementation, the thermal treatment is
operated at a
temperature above 450 C.
[184] According to a possible implementation, the thermal treatment is
operated at a
residence time of up to 300 minutes.
[185] According to a possible implementation, the residence time of the
thermal treatment
is above 15 minutes.
[186] According to a possible implementation, the residence time of the
thermal treatment
is above 60 minutes.
[187] According to a possible implementation, the residence time of the
thermal treatment
is above 90 minutes.
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[188] According to a possible implementation, the residence time of the
thermal treatment
is above 150 minutes.
[189] According to a possible implementation, the residence time of the
thermal treatment
is above 180 minutes.
[190] According to a possible implementation, the residence time of the
thermal treatment
is above 210 minutes.
[191] According to a possible implementation, the thermal treatment is
operated at a
pressure between 50 psig and 1500 psig.
[192] According to a possible implementation, the thermal treatment is
operated at a
pressure between 50 psig and 1000 psig.
[193] According to a possible implementation, separating the deasphalted
bitumen from
the production fluid comprises removing water and solids from the production
fluid.
[194] According to a possible implementation, separating the deasphalted
bitumen from
the production fluid comprises recovering at least a portion of the asphaltene-
precipitating
solvent from the production fluid to obtain a recovered asphaltene-
precipitating solvent for
reintroduction into the subsurface formation.
[195] According to a possible implementation, introducing the asphaltene-
precipitating
solvent into the subsurface formation comprises vaporizing the asphaltene-
precipitating
solvent at surface, and injecting the asphaltene-precipitating solvent into
the subsurface
formation in vapor phase.
[196] According to a possible implementation, conditions of the in situ
bitumen recovery
operation comprise providing a solvent-to-bitumen ratio of the mobilized fluid
that is
sufficiently high to cause the in situ precipitation of asphaltenes at
operating extraction
temperatures and pressures.
[197] According to a possible implementation, the solvent-to-bitumen ratio of
the mobilized
fluid is sufficiently high to cause substantially all of the asphaltenes to
precipitate such that
the deasphalted bitumen fraction is fully deasphalted.
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[198] According to a possible implementation, the solvent-to-bitumen ratio of
the mobilized
fluid is provided to cause partial precipitation of asphaltenes such that the
deasphalted
bitumen fraction comprises a reduced asphaltene content.
[199] According to a possible implementation, the process further comprises
combining
the deasphalted bitumen with a second hydrocarbon material to obtain a
combined
deasphalted bitumen material that is subjected to the thermal treatment.
[200] According to a possible implementation, the second hydrocarbon material
comprises a second deasphalted bitumen.
[201] According to a possible implementation, the second deasphalted bitumen
is
obtained from a second subsurface formation.
[202] According to a possible implementation, the deasphalted bitumen and the
second
hydrocarbon material are combined in relative proportions so that the combined
deasphalted bitumen material has a predetermined composition based on desired
operating parameters of the thermal treatment.
[203] According to a possible implementation, the process further comprises
combining
multiple production fluids respectively obtained from a plurality of in situ
recovery wells to
form a combined production fluid, and separating the deasphalted bitumen from
the
combined production fluid.
[204] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises maintaining the deasphalted bitumen in liquid
phase during
the thermal treatment.
[205] According to a possible implementation, maintaining the deasphalted
bitumen in
liquid phase comprises providing conditions to cause a transfer of hydrogen
from the
heavy fraction to the light fraction directly in the liquid phase.
[206] According to a possible implementation, the thermal treatment comprises
supplying
the deasphalted bitumen to a thermal treatment vessel and withdrawing the
partially
upgraded bitumen product from the thermal treatment vessel as a single stream
from a
product outlet.
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[207] According to a possible implementation, the thermal treatment comprises
feeding
the single stream of partially upgraded bitumen product to a gas separator and
removing
at least a portion of a gas phase from the partially upgraded bitumen product.
[208] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises adding an external source of hydrogen to the
deasphalted
bitumen.
[209] According to a possible implementation, subjecting the deasphalted
bitumen to the
thermal treatment comprises adding a hydrogen transfer agent to the
deasphalted
bitumen.
[210] According to a possible implementation, the external source of hydrogen
is a
diatomic hydrogen-containing gas.
[211] According to a possible implementation, the hydrogen transfer agent
comprises
paraffins, naphthenes, naphtheno-aromatics and/or aromatics.
[212] According to a possible implementation, the hydrogen transfer agent
comprises at
least one of butane, propane, methane, tetralin, decalin, and anthracene.
[213] According to a possible implementation, the hydrogen transfer agent
comprises a
hydrogen donor.
[214] According to a possible implementation, the hydrogen donor comprises at
least one
of tetralin, decalin, synthetic crude oil, fractions of synthetic crude oil,
tight oil, shale oil
and light crude oils.
[215] According to a possible implementation, the process further comprises
diluting the
partially upgraded bitumen product with a diluent to obtain a diluted bitumen
product.
[216] According to a possible implementation, the diluent comprises an
aromatic diluent,
a naphthenic diluent, natural gas condensates, synthetic crude, a fraction of
synthetic
crude oil or streams thereof.
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[217] According to a possible implementation, the diluted bitumen product is
diluted to a
predetermined pipeline specification, and is also based on the determined
property of the
partially upgraded bitumen product.
[218] According to a possible implementation, the process further comprises
recovering
heat from the partially upgraded bitumen product and reusing at least a
portion of the
recovered heat in the in situ bitumen recovery operation.
[219] According to a possible implementation, the heat is at least partly
reused for pre-
heating a process stream that is part of the in situ bitumen recovery
operation prior to a
unit operation.
[220] According to a possible implementation, the deasphalted bitumen has a
variable
composition over time.
[221] According to a possible implementation, the deasphalted bitumen has a
higher
asphaltene content during an earlier stage of the in situ bitumen recovery
operation, and
a lower asphaltene content during a later stage of the in situ bitumen
recovery operation.
[222] According to a possible implementation, the earlier stage comprises a
startup stage,
and the later stage comprises a normal operation stage of the in situ bitumen
recovery
operation.
[223] According to a possible implementation, the process further comprises
controlling
the in situ bitumen recovery operation or the thermal treatment or a
combination thereof,
based on the variable composition of the deasphalted bitumen.
[224] According to a possible implementation, the thermal treatment is
operated at lower
severity conditions when the deasphalted bitumen has a higher asphaltene
content, and
is operated at higher severity conditions when the deasphalted bitumen has a
lower
asphaltene content.
[225] According to a possible implementation, the thermal treatment is
continuously
controlled based on the variable composition of the deasphalted bitumen.
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[226] According to a possible implementation, the thermal treatment is
intermittently
controlled based on the variable composition of the deasphalted bitumen.
[227] In accordance with another aspect, there is provided a system for
producing a
partially upgraded bitumen product. The system comprises an in situ bitumen
recovery
facility, comprising: a horizontal injection well located in a subsurface
formation and
configured for injecting an asphaltene-precipitating solvent into the
subsurface formation
to contact bitumen contained therein at conditions to cause in situ
precipitation of at least
a portion of asphaltenes within the subsurface formation to produce a
precipitated
asphaltene material and a mobilized fluid comprising a deasphalted bitumen
fraction; a
horizontal production well located in the subsurface formation below the
horizontal
injection well, thereby forming a well pair, the horizontal production well
being configured
to recover the mobilized fluid to surface as a production fluid that comprises
the
deasphalted bitumen fraction, water, solids and a portion of the asphaltene-
precipitating
solvent while leaving a majority of the precipitated asphaltene material
within the
subsurface formation; and a surface separation unit in fluid communication
with the
horizontal production well and configured to separate deasphalted bitumen from
the
production fluid; and a thermal treatment facility in fluid communication with
the in situ
bitumen recovery facility, and configured to subject the deasphalted bitumen
to thermal
treatment at about or below incipient coking conditions to produce the
partially upgraded
bitumen product.
[228] According to a possible implementation, the system further comprises a
measurement unit configured to determine at least one property of the
deasphalted
bitumen and/or at least one property of the partially upgraded bitumen
product, and a
control unit configured to receive information from the measurement unit and
to adjust at
least one operating parameter of the thermal treatment facility and/or or the
in situ bitumen
recovery facility based on the at least one determined property.
[229] According to a possible implementation, the horizontal production well
and the
horizontal injection well are configured as a well pair for gravity dominated
recovery.
[230] According to a possible implementation, the asphaltene-precipitating
solvent
comprises an alkane solvent.
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[231] According to a possible implementation, the alkane solvent comprises
propane,
butane, pentane, hexane, heptane or a mixture thereof.
[232] According to a possible implementation, the alkane solvent comprises
propane.
[233] According to a possible implementation, the alkane solvent comprises
butane.
[234] According to a possible implementation, the alkane solvent comprises
pentane.
[235] According to a possible implementation, the thermal treatment facility
comprises a
thermal treatment vessel configured to receive and thermally treat the
deasphalted
bitumen.
[236] According to a possible implementation, the thermal treatment vessel is
configured
to operate at a temperature above 200 C.
[237] According to a possible implementation, the thermal treatment vessel is
configured
to operate at a temperature above 250 C.
[238] According to a possible implementation, the thermal treatment vessel is
configured
to operate at a temperature above 300 C.
[239] According to a possible implementation, the thermal treatment vessel is
configured
to operate at a temperature above 350 C.
[240] According to a possible implementation, the thermal treatment vessel is
configured
to operate at a temperature above 400 C.
[241] According to a possible implementation, the thermal treatment vessel is
configured
to operate at a temperature above 450 C.
[242] According to a possible implementation, the thermal treatment vessel is
configured
to operate at a residence time of up to 300 minutes.
[243] According to a possible implementation, the residence time of the
thermal treatment
vessel is above 15 minutes.
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[244] According to a possible implementation, the residence time of the
thermal treatment
vessel is above 60 minutes.
[245] According to a possible implementation, the residence time of the
thermal treatment
vessel is above 90 minutes.
[246] According to a possible implementation, the residence time of the
thermal treatment
vessel is above 150 minutes.
[247] According to a possible implementation, the residence time of the
thermal treatment
vessel is above 180 minutes.
[248] According to a possible implementation, the residence time of the
thermal treatment
vessel is above 210 minutes.
[249] According to a possible implementation, the thermal treatment vessel is
configured
to operate at a pressure between 50 psig and 1500 psig.
[250] According to a possible implementation, the thermal treatment vessel is
configured
to operate at a pressure between 50 psig and 1000 psig.
[251] According to a possible implementation, the surface separation unit is
further
configured to separate water and solids from the production fluid.
[252] According to a possible implementation, the surface separation unit is
further
configured to recover at least a portion of the asphaltene-precipitating
solvent from the
production fluid to obtain a recovered asphaltene-precipitating solvent for
reintroduction
into the subsurface formation via the horizontal injection well.
[253] According to a possible implementation, the in situ bitumen recovery
facility
comprises a vaporization unit configured to vaporize the asphaltene-
precipitating solvent
at surface prior to supplying to the horizontal injection well for
introduction as a vapor
phase.
[254] According to a possible implementation, the thermal treatment facility
is configured
such that the deasphalted bitumen is maintained in liquid phase during the
thermal
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treatment to cause a transfer of hydrogen from the heavy fraction to the light
fraction
directly in the liquid phase.
[255] According to a possible implementation, the thermal treatment vessel has
a single
product outlet for withdrawing the partially upgraded bitumen product from the
thermal
treatment vessel as a single stream.
[256] According to a possible implementation, the thermal treatment facility
further
comprises a gas separator configured to receive the single stream of partially
upgraded
bitumen product and remove at least a portion of a gas phase from the
partially upgraded
bitumen product.
[257] According to a possible implementation, the thermal treatment facility
comprises no
external hydrogen addition unit.
[258] According to a possible implementation, the thermal treatment facility
comprises an
external hydrogen addition unit configured to add an external source of
hydrogen to the
deasphalted bitumen.
[259] According to a possible implementation, the thermal treatment facility
comprises an
external hydrogen addition unit configured to add a hydrogen transfer agent to
the
deasphalted bitumen.
[260] According to a possible implementation, the system further comprises a
dilution unit
configured to receive the partially upgraded bitumen product from the thermal
treatment
facility and to dilute the partially upgraded bitumen product with a diluent
to obtain a diluted
bitumen product.
[261] According to a possible implementation, the system further comprises a
heat
recovery unit configured to recover heat from the thermal treatment facility
and to reuse at
least a portion of the recovered heat in the in situ bitumen recovery
facility.
[262] According to a possible implementation, the heat is recovered from the
partially
upgraded bitumen product.
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[263] According to a possible implementation, the heat is at least partly
reused for pre-
heating a process stream of the in situ bitumen recovery facility prior to a
unit operation.
[264] According to a possible implementation, the deasphalted bitumen has a
variable
composition over time.
[265] According to a possible implementation, the deasphalted bitumen has a
higher
asphaltene content during an earlier stage of operating the in situ bitumen
recovery facility,
and a lower asphaltene content during a later stage of operating the in situ
bitumen
recovery facility.
[266] According to a possible implementation, the earlier stage comprises a
startup stage,
and the later stage comprises a normal operation stage of the in situ bitumen
recovery
facility.
[267] According to a possible implementation, the system further comprises a
control
system configured to control the in situ bitumen recovery facility or the
thermal treatment
or a combination thereof, based on the variable composition of the deasphalted
bitumen.
[268] According to a possible implementation, the control system is configured
to control
operation of the thermal treatment facility at lower severity conditions when
the
deasphalted bitumen has a higher asphaltene content, and at higher severity
conditions
when the deasphalted bitumen has a lower asphaltene content.
[269] According to a possible implementation, the control system is configured
to
continuously control the thermal treatment facility based on the variable
composition of
the deasphalted bitumen.
[270] According to a possible implementation, the control system is configured
to
intermittently control the thermal treatment facility based on the variable
composition of
the deasphalted bitumen.
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BRIEF DESCRIPTION OF THE DRAWINGS
[271] Figure 1 is a schematic representation of a process for partially
upgrading bitumen,
including a well pair including an injection well and a production well
located in a
subsurface formation and an at-surface thermal treatment stage for treating
the
deasphalted bitumen separated from the production fluid.
[272] Figure 2 is a flow diagram of a process for treating deasphalted bitumen
including a
separation step, a thermal treatment and a dilution step.
[273] Figure 3 is a flow diagram of a process for treating a partially
deasphalted bitumen
stream including a solvent deasphalting step followed by thermal treatment
step.
[274] Figure 4 is a flow diagram of a process for treating various streams of
deasphalted
and partially deasphalted bitumen materials including a thermal treatment step
where
properties of streams are monitored and the process is controlled.
[275] Figure 5 is a flow diagram of a process for treating a production fluid
from an in situ
operation, including a separation step, a storage or holding step and a
thermal treatment
step.
[276] Figure 6 is a flowchart of a control strategy for a process for
producing a partially
deasphalted bitumen product.
[277] Figure 7 is a flowchart of another control strategy for a process for
producing a
partially deasphalted bitumen product.
[278] Figure 8 is a process diagram showing an example of a thermal treatment
unit and
downstream processing.
DETAILED DESCRIPTION
[279] Techniques described herein relate to the recovery and treatment of
bitumen and
include a subsurface deasphalting treatment to remove at least some
asphaltenes from
bitumen within the reservoir and recover deasphalted bitumen, followed by an
at-surface
thermal treatment of the deasphalted bitumen to produce partially upgraded
bitumen. The
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combined treatments of subsurface deasphalting followed by at-surface mild
thermal
treatment can be globally referred to herein as a "partial upgrading" process.
[280] The deasphalting stage is performed in situ within a subsurface
formation, such as
an oil sands formation. The subsurface formation can include hydrocarbon
materials,
water and solids. The bitumen within the formation includes various
hydrocarbon
components, including heavier asphaltenes and lighter maltenes. Bitumen also
includes
various non-hydrocarbon compounds (e.g., sulfur, metals, etc.) and micro-
carbon residue,
which may tend to associate with certain hydrocarbon components of the bitumen
such
as asphaltenes.
[281] The in situ deasphalting stage uses the injection of a deasphalting
solvent, such as
propane or butane, at conditions that mobilize bitumen in the reservoir and
cause
asphaltene precipitation. The deasphalted mobilized bitumen is then recovered
as part of
a production fluid that also includes solvent, water and solids. The in situ
deasphalting
stage can employ various well configurations to inject the solvent and recover
the
production fluid.
[282] The thermal treatment stage is conducted ex situ, i.e., using treatment
units that are
provided at surface. The deasphalted bitumen separated from the production
fluid
recovered from an in situ bitumen recovery operation, is supplied to the
thermal treatment
stage to produce the partially upgraded bitumen.
[283] The partial upgrading process as described herein facilitates modifying
certain
physicochemical properties of bitumen in order to improve its suitability for
pipeline
transportation. For instance, precipitating and rejecting asphaltenes in situ
within a
subsurface formation and thermally treating the deasphalted bitumen can result
in a
partially upgraded bitumen product having a reduced viscosity and/or density.
The
viscosity and density reduction can, in turn, help reduce or eliminate diluent
requirements
for the partially upgraded bitumen product to meet pipeline specifications. A
non-limiting
example of a pipeline specification can require a viscosity of 350 cSt or less
at the
reference temperature of the pipeline and a density of 940 kg/m3 or less.
Other
requirements can also be part of a pipeline specification, such as the olefin
content of the
bitumen, for instance an olefin content of less than 1 wt% (1-decene
equivalent basis). In
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contrast to deasphalting bitumen using at-surface facilities, subsurface
deasphalting can
be beneficial since at least a portion of the asphaltenes contained in the
bitumen can
remain in the subsurface formation, thereby avoiding the need for handling and
treatment
of asphaltene materials at surface.
[284] The subsurface deasphalting of bitumen can occur in the context of a
solvent-
assisted gravity drainage operation, where a precipitating solvent (e.g., a
paraffinic solvent
such as propane or butane) is introduced into a subsurface formation, with or
without
steam, to facilitate bitumen recovery from the subsurface formation. For a
solvent-assisted
gravity drainage operation, the well configuration would typically include a
horizontal well
pair including an injection well overlying a production well. The introduction
of the
precipitating solvent into the subsurface formation can play several roles,
e.g., the solvent
can help increase the mobility of the bitumen by dissolution and heating to
facilitate
drainage of mobilized bitumen toward the production well, and the solvent can
induce in
situ precipitation of at least a portion of the asphaltene content of the
bitumen such that a
majority of precipitated asphaltenes remain within the subsurface formation.
The
production fluid recovered via the production well can thus include mobilized
bitumen that
includes a deasphalted bitumen fraction and a portion of solvent.
[285] The solvent to be injected into the subsurface formation can be selected
and injected
at conditions to facilitate asphaltene precipitation. Asphaltene precipitation
is a
phenomenon that can depend on temperature, pressure, solvent type and
concentration
relative to the bitumen, bitumen composition, and other factors. The type of
solvent
injected into the subsurface formation can be determined at least in part
based on the
extent of asphaltene rejection that is desired, such that a deasphalted
bitumen having
given properties can be recovered from the subsurface formation.
[286] Paraffinic solvents, also referred to as alkanes, such as propane,
butane, and
pentane, are known as having the property of promoting the precipitation of
asphaltenes
under certain conditions. The solubility of asphaltenes in paraffinic solvents
is relatively
low, for instance in contrast to the solubility of asphaltenes in aromatic
solvents.
Asphaltenes are a component of heavy hydrocarbons that can indeed be defined
in
accordance with their solubility in given solvents: asphaltenes are defined as
dissolving in
toluene and precipitating in certain paraffinic solvents (n-alkanes).
Paraffinic solvents that
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can induce precipitation typically include Cl-C7 paraffins, but higher C-
number paraffinic
solvents can also be considered as solvents to precipitate asphaltenes under
certain
conditions. In some implementations, the paraffinic solvents can be propane,
butane, or
pentane, and mixtures thereof.
[287] The subsurface deasphalting as described herein can produce deasphalted
bitumen
that can have different levels of asphaltenes. For example, the deasphalted
bitumen can
be partially deasphalted with a lower or medium range of asphaltene depletion
or can be
substantially deasphalted. The extent of precipitation of the asphaltenes
within the
subsurface formation can depend, for instance, on the type of solvent or
combination of
solvents introduced into the subsurface formation, the asphaltene content in
the bitumen,
the composition of the asphaltenes, the presence of other components such as
resins in
the bitumen, the temperature and pressure conditions within the subsurface
formation,
and the quantity of solvent used, which can be expressed as a solvent-to-
bitumen (SIB)
ratio. In addition, the extent of deasphalting can vary over time and depend
on the stage
or operating conditions of the in situ recovery operation, such that the
asphaltene content
in the produced deasphalted bitumen can also vary over time.
[288] As mentioned above, the production fluid recovered from the production
well of the
in situ recovery operation includes a deasphalted bitumen fraction as well as
other
materials, such as solvent, water and solids. The production fluid can be
processed in a
surface facility to remove water and solids, recover solvent for reinjection
into the
subsurface formation, and thus produce a deasphalted bitumen stream.
[289] The deasphalted bitumen can then be used as a deasphalted bitumen
feedstock in
a thermal treatment stage in order to produce the partially upgraded bitumen
product. The
thermal treatment of the deasphalted bitumen can be performed at temperature
and
pressure conditions that are below and/or close to incipient coking
conditions. In other
words, the thermal treatment conditions can be provided to avoid conversion of
heavy
hydrocarbon components into coke, although some coke precursors can form.
[290] During the thermal treatment, both the heavy and light fractions of the
deasphalted
bitumen product undergo various reactions, including thermal cracking. The
cracking
reactions result in the formation of smaller hydrocarbon molecules, which in
some
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implementations can have a positive impact on viscosity reduction and bitumen
product
quality. "Fraction" as used herein with respect to the thermal treatment step
refers to a
collection of hydrocarbons that can be recovered and/or processed together.
The fraction
can contain, but is not limited to, hydrocarbons that are similar in
composition, physical
characteristics (e.g., viscosity), boiling point, location, geologic origin,
or in recoverability
or processability. A heavy fraction as used herein refers to a hydrocarbon
fraction having
a boiling point above about 525 C. Typically, the heavy fraction can include
asphaltenes,
if present, along with smaller amounts of resins, aromatics and other
hydrocarbon
compounds. A light fraction as used herein with respect to the thermal
treatment step
refers to a hydrocarbon fraction having a boiling point of less than 525 C.
For instance,
the light fraction can include hydrocarbon components that are commonly
referred to as
vacuum gas oil, heavy gas oil, light gas oil and distillates in terms of
boiling points.
[291] In some implementations, thermally treating the deasphalted bitumen at
temperature and pressure conditions to remain below and/or close to incipient
coking
conditions can be performed at higher severity conditions than the temperature
and
pressure conditions necessary for whole bitumen to remain below and/or close
to incipient
coking conditions. The term "severity" as used herein refers to the severity
of the
conditions of temperature and residence time at which bitumen is treated. For
example,
the severity can be expressed in terms of an equivalent reaction time (ERT) in
seconds of
residence time when a reactor is operating at 427 C (800 F). The ERT
corresponds to the
residence time that would achieve the same conversion of heavy material at a
given
temperature as if the reaction was conducted at 427 C (800 F).
[292] In some implementations, operating the thermal treatment at higher
severity
conditions but still below the onset of coke formation, can be made possible
at least in part
because asphaltene rejection within the subsurface formation can facilitate
the production
of a deasphalted bitumen having a reduced amount of impurities as well as a
reduced
asphaltene content. Operating the thermal treatment at higher severity
conditions can in
turn achieve a higher residue conversion, i.e., the 525 C+ residue fraction
from
deasphalted bitumen can be converted to a greater extent compared to virgin
525 C+
bitumen material due to the subsurface rejection of asphaltenes.
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[293] In some implementations, the thermal treatment described herein can be
considered
as a mild thermal treatment. Examples of operating conditions for a mild
thermal treatment
include performing the thermal treatment at a temperature between 200 C and
475 C, or
between about 250 C and about 450 C. In other implementations, the temperature
of the
thermal treatment is between about 350 C and about 450 C, between about 350 C
and
about 425 C, between about 360 C and about 440 C, or between about 375 C and
about
425 C. In some implementations, the gauge pressure to which the bitumen
feedstock is
subjected to during the thermal treatment is from about 50 psig to about 1500
psig, from
about 50 psig to about 1000 psig, or from about 200 psig to 700 psig. In some
implementations, the bitumen feedstock is subjected to the thermal treatment
for a time
period of up to about 3000 minutes, up to about 300 minutes, from about 15
minutes to
about 240 minutes, from about 60 minutes to about 240 minutes, or from about 5
minutes
to about 60 minutes.
[294] In some implementations, the severity of the thermal treatment is below
the severity
required for incipient coke formation. In other implementations, substantially
no coke is
formed during the thermal treatment. In particular, in some implementations,
the severity
of the thermal treatment can be kept between 900s and 1500s ERT to minimize
coke
formation. In some implementations, for instance when the asphaltene content
of the
deasphalted bitumen subjected to thermal cracking is below a given threshold,
less
asphaltenes are available to contribute to coking, thus contributing to delay
the onset of
coking and allowing a higher severity thermal treatment to be performed.
Accordingly, in
some implementations, the operating conditions of the at-surface thermal
treatment
following subsurface solvent deasphalting can be increased to between 1500s
and 3000s
ERT or between1500s and 5000s ERT.
[295] Depending on the extent of asphaltene rejection that occurred within the
subsurface
formation and thus of the asphaltene content of the recovered deasphalted
bitumen, the
operating conditions of the thermal treatment can be chosen such that the
components of
the deasphalted bitumen are substantially maintained in liquid phase during
the thermal
treatment to enable hydrogen transfer to occur from the heavy fraction to the
light fraction.
For example, in some implementations, it may be desirable to retain a portion
of the
asphaltenes in the deasphalted bitumen, thus producing partially deasphalted
bitumen
from the reservoir, to promote hydrogen transfer from the heavy fraction to
the light
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fraction. Accordingly, the subsurface solvent deasphalting can be performed at
conditions
that allow retaining a portion of the asphaltenes in the recovered deasphalted
bitumen. In
turn, subjecting deasphalted bitumen that includes both a heavy and a light
fractions to a
thermal treatment at conditions that allow maintaining both the heavy and
light fractions in
liquid phase can facilitate leveraging the hydrogen content of the heavy
fraction by
enabling efficient hydrogen transfer from the heavy fraction to the light
fraction,
contributing to the enrichment of the light fraction with hydrogen, which can
have a positive
impact on viscosity reduction and bitumen product quality.
[296] The operating parameters of the thermal treatment can be adjusted taking
into
consideration the characteristics of the deasphalted bitumen used as the
feedstock, to
obtain partially upgraded bitumen according to given specifications.
Controlling various
parameters influencing the production of the deasphalted bitumen, including
adjusting the
operating parameters of the subsurface deasphalting to influence the
precipitation of the
asphaltenes within the formation and/or adjusting a property of the recovered
deasphalted
bitumen, can also contribute to obtaining deasphalted bitumen having given
characteristics, which in turn can allow the operation of the thermal
treatment to be such
that the partially upgraded bitumen also has given characteristics.
[297] As mentioned above, variation in the asphaltene content of the
deasphalted bitumen
product can also influence the desirability for the addition of an external
source of
hydrogen or of a hydrogen transfer agent during the thermal treatment so as to
produce a
partially upgraded bitumen according to given characteristics. For instance,
in some
implementations, when the deasphalted bitumen has a low asphaltene content,
the
severity of the thermal treatment can be controlled higher, or a hydrogen
transfer agent
can be added during the thermal treatment to reduce the formation of by-
products such
as olefins and/or to delay the onset of coke formation. In other
implementations, when the
deasphalted bitumen has an asphaltene content above a given threshold, the
thermal
treatment can be performed at a lower severity, in which case the addition of
a hydrogen
transfer agent can be omitted or added in a lesser amount than when the
asphaltene
content is below the given threshold. Thus, asphaltene content of the
deasphalted bitumen
can be measured upstream of the thermal treatment and the measured value can
be used
to control the process parameters of the thermal treatment (e.g., temperature,
residence
time, hydrogen addition, hydrogen transfer agent addition, and so on).
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[298] In some implementations, both of the approaches mentioned above to
control and
adjust the operating conditions of the thermal treatment and those related to
the production
of deasphalted bitumen, as well as the adjustments with regard to the
characteristics of
the recovered deasphalted bitumen, can be combined to allow additional
opportunities for
maintaining performance and/or fine-tuning of the partial upgrading operations
such that
given characteristics of the partially upgraded bitumen product can be
obtained. Thus,
both the in situ deasphalting stage and the thermal treatment stage can be
controlled
based on various measurements and design parameters in order to coordinate the
two
stages.
[299] The partially upgraded bitumen obtained following thermal treatment can
be
removed from a thermal treatment vessel as a single stream that includes all
of the
hydrocarbon components. In some implementations, the single stream of
partially
upgraded bitumen product can then be subjected to separation steps to produce
various
streams, such as one or more light fractions and one or more heavy fractions.
The light
fractions can include naphtha, distillate, and/or gasoil, and the heavy
fraction can include
material having a boiling point above 525 C. It should be noted that the
separation of the
partially upgraded bitumen product stream can be performed using multiple
separation
units arranged in series so that downstream separation units receive one or
more of the
output streams of an upstream unit.
[300] In some implementations, the thermal treatment can also be conducted
such that a
low quantity of non-condensable hydrocarbon gas is generated. Thus, the
partially
upgraded bitumen product can be a substantially liquid-phase stream with a
minor amount
of non-condensable gas (e.g., less than 5 wt%), which can be removed prior to
subsequent
processing or storage.
[301] Figure 8 illustrates an example implementation of the thermal treatment
followed by
some downstream processing, and will be described in more detail further
below.
Subsurface solvent deasphalting followed by thermal treatment implementations
[302] Techniques described herein facilitate partially upgrading bitumen and
include
producing deasphalted bitumen using an in situ solvent-assisted recovery
process and
then subjecting the deasphalted bitumen to thermal treatment.
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[303] The in situ solvent-assisted recovery process can include various
processes and
well configurations for introducing solvent into the reservoir to help
mobilize bitumen. The
in situ solvent-assisted recovery process can use steam-solvent co-injection,
pure solvent
injection, solvent-dominated injection with some other fluids being co-
injected, methods
that utilize solvent injection as well as in situ heating via downhole heaters
(e.g., electric
resistive heaters, electromagnetic heaters, fluid circulation heaters) or
concurrent or
sequential combinations of different processes. The solvent can be vaporized
at surface
for injection, for instance to be injected as superheated solvent which may be
at different
degrees of superheat, vaporized in situ with heaters as it enters the
reservoir, or injected
as a liquid in some scenarios.
[304] The in situ process can utilise a horizontal well pair that includes an
upper injection
well and a lower production well vertically spaced apart from the injection
well.
Alternatively, the in situ process can use a single well that is operated
cyclically between
injection and production modes. Other well configurations and processes are
also
possible.
[305] While various processes can be used, certain conditions that are
provided in the
subterranean formation can cause some degree of in situ asphaltene
precipitation. Thus,
the solvent should be selected and provided in sufficient amount under
extraction
conditions such that some of the solvent dissolves the bitumen and induces
precipitation
of asphaltenes in situ. The mobilized bitumen, which has a reduced asphaltene
content,
then reports to the production well and is pumped to the surface. The
deasphalted bitumen
is characterized at least by having a reduced asphaltene content compared to
its native
state. Bitumen having a reduced asphaltene content can facilitate performance
of
subsequent upgrading treatments, such as the thermal treatment described
herein.
[306] In situ deasphalting of bitumen contained in an oil sands formation will
now be
described in further detail with reference to the figures.
[307] Figure 1 shows a solvent-assisted in situ recovery process to mobilize
bitumen and
produce mobilized bitumen. The solvent-assisted recovery process can include a
well pair
provided in a subsurface formation 26, the well pair having an injection well
10 and a
production well 16. The injection well 10 and the production well 16 are
generally parallel
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and separated by an interwell region 22. The injection well 10 includes a
vertical portion
12 and a horizontal portion 14 extending from the vertical portion 12, and the
production
well 16 includes a vertical portion 18 and a horizontal portion 20 extending
from the vertical
portion 18. Alternatively, the solvent-assisted recovery process can be
performed using a
single horizontal or vertical well that is operated cyclically between
injection and production
modes.
[308] The solvent-assisted recovery process can also use various other well
configurations and operating schemes. In addition, the solvent-assisted
recovery process
can inject relatively pure solvent in liquid or vapour phase where the solvent
is provided
as a vapour at surface or is vaporized downhole using a heater provided in the
injection
well. The solvent-assisted recovery process can use a combination of steam and
solvent
that are co-injected into the subsurface formation. For steam-solvent co-
injection, the
steam and solvent can be combined at surface and can have relative quantities
such that
solvent is the dominant component.
[309] The solvent-assisted recovery process can include various stages,
including a
startup stage, a normal operation stage, and a mature or wind-down stage. When
solvent
is injected during a startup phase of the solvent-assisted recovery process,
the startup
solvent can be different than the solvent injected during the normal operation
stage and
the mature stage. In some implementations, the solvent used during the startup
stage is
selected to mobilize hydrocarbons and establish fluid communication, for
instance
between the injection well and the production well of the well pair. The
solvent used during
the startup stage can be a solvent that is less likely to induce asphaltene
precipitation or
that would not induce precipitation, since it can be desirable to avoid such
precipitation in
proximity to the injection well and/or the production well, i.e., in the
interwell region, to
avoid impairing the flow of the mobilized bitumen and clogging of the wells.
Aromatic
solvents, such as toluene, xylene and diesel, are examples of solvents that
can be used
during the startup stage to mobilize bitumen while avoiding asphaltene
precipitation.
[310] The solvent-assisted recovery process generally transitions to the
normal operation
stage of the solvent-assisted recovery process once fluid communication
between the
injection well and the production well has been established, and the
development of a
solvent chamber has been initiated, i.e., following the startup stage. For a
gravity drainage
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process using a well pair, the normal operation stage can be considered a
stage during
which mobilized bitumen is recovered to the surface as a production fluid and
a solvent
chamber grows upward and outward from the injection well. According to the
techniques
described herein, the solvent introduced into the subsurface formation during
the normal
operation stage can be chosen so as to include an asphaltene-precipitating
solvent to
induce precipitation of asphaltenes within the subsurface formation. At least
a portion of
the precipitated asphaltenes can thus remain within the subsurface formation,
such that
the production fluid comprising a deasphalted bitumen fraction can be
recovered to the
surface. Most or a substantial portion of the precipitated asphaltenes can
remain
deposited within the subsurface formation during the recovery process and even
after the
recovery process has been completed. However, in some scenarios, asphaltenes
that
have previously precipitated in the subsurface formation and that have been
left in the
solvent chamber can be carried down by draining fluids into the pool of
mobilized bitumen
in proximity of the production well and can be produced along with the
production fluid. In
such scenarios, asphaltene precipitates can thus be entrained in the
production fluid along
with the deasphalted bitumen fraction. Whether some asphaltene precipitates
are
entrained into the production fluid can depend on various factors, such as
drainage rates,
fluid properties, geological properties of the reservoir, and characteristics
of the
precipitated asphaltenes.
[311] It is also noted that the "majority" of asphaltene precipitates that
form within the
formation are left in the formation during the in situ recovery process as
described herein.
This means that during the deasphalting in situ recovery process, most of the
precipitated
asphaltenes remain in the formation and only a minor portion could be
recovered with the
production fluid. However, it is possible to perform an additional process
after the
deasphalting in situ recovery process in order to recover a further amount of
the
precipitated asphaltenes that were left in the formation, of course using an
alternative
recovery process. If such an additional recovery process were implemented, it
could
enable the recovery of asphaltenes that were previously precipitated such that
the overall
amount of precipitated asphaltenes left in the formation after the additional
recovery
process would not be a majority of the originally precipitated asphaltenes. In
other words,
while a majority of the asphaltene precipitates are left in the formation
during the
deasphalting in situ recovery process, these asphaltene precipitates could be
recovered
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later using other recovery processes and thus do not have to remain in the
reservoir
indefinitely.
[312] In some implementations, a combination of solvents can be used, for
instance a
combination of solvents comprising at least one asphaltene-precipitating
solvent and
another solvent such as an aromatic solvent. However, when an aromatic solvent
is
present, the overall combination of solvents is one that allows precipitation
of at least a
portion of the asphaltenes within the subsurface formation.
[313] In some implementations, the production fluid and/or the deasphalted
bitumen
fraction recovered to the surface can have a variable asphaltene content over
time. For
instance, when transitioning from the startup stage to the normal operation
stage, the
production fluid can include a decreasing amount of asphaltenes as the
deasphalting
solvent content within the reservoir and in the production fluid increases.
For example,
one factor that can influence the level of deasphalting over time can be the
type of startup
process used prior to the beginning of the normal operation stage. For
instance, for startup
processes that include injecting an aromatic solvent into the subsurface
formation, the
level of deasphalting can range from a zero-deasphalted bitumen during startup
and at
the beginning of the normal operation stage to a fully-deasphalted bitumen as
the
deasphalting solvent is used in higher concentrations over time. For startup
processes
that include injecting or circulating steam as a mobilizing fluid and/or
providing heat to the
interwell region (e.g., through electric resistive heaters, RF heaters or
other heating
means), the level of deasphalting can also increase over time from the startup
stage with
little to no deasphalting to the normal operation stage when deasphalting
solvent is used,
since such types of startup processes do not cause deasphalting and can result
in a high
amount of asphaltenes in the production fluid during startup.
[314] In contrast, for startup processes that include injecting a paraffinic
solvent into the
subsurface formation at elevated concentrations, the level of deasphalting can
be more
constant over time, since deasphalting can occur during the startup process,
such that the
transition to the normal operation stage occurs with less fluctuations in
terms of asphaltene
content in the production fluid. In other scenarios, a deasphalting solvent
could be used
for startup at certain concentrations and startup conditions that would enable
deasphalting, and then deasphalting solvent could be used at alternative
conditions (e.g.,
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lower solvent concentrations or different temperature conditions) during the
normal
operation stage such that less deasphalting would occur during normal
operation
compared to startup. While various implementations are possible to result in
varying levels
of deasphalting over time, it is noted that using a low or non deasphalting
startup method
followed by higher deasphalting for normal operation can be preferred.
[315] Once the solvent-assisted recovery process has been in operation for a
certain
period of time and the recovery rate of the hydrocarbon production has started
to decrease
to uneconomical levels, the subsurface formation can be said to transition to
a mature
subsurface formation. Variables other than the recovery rate can also be
indicative of a
subsurface formation that has reached a mature stage. Wind-down strategies can
then be
put in place to manage the mature subsurface formation.
[316] As mentioned above, the techniques described herein can allow for a
majority of the
precipitated asphaltenes remain in the subsurface formation such that a
production fluid
that comprises a deasphalted bitumen fraction can be produced to the surface.
It should
be noted that, in some implementations, techniques can be put in place to
recover at least
some of the precipitated asphalted to the surface, for instance for further
treatment.
[317] Referring back to Figure 1, the solvent-assisted recovery process is
shown in a
normal operation stage, where the solvent includes or consists substantially
of an
asphaltene-precipitating solvent 24, such as a paraffinic solvent, and
contributes to the
precipitation and deposition of asphaltenes within the subsurface formation
26. In some
implementations, the choice of asphaltene-precipitating solvent 24 as well as
its
concentration are factors that can be varied to produce deasphalted bitumen 54
having
given characteristics. The concentration of the asphaltene-precipitating
solvent 24 is
chosen such that once in the subsurface formation 26, this concentration is
sufficient to
allow asphaltene precipitation. Other factors such as pressure and temperature
of the
solvent chamber that forms within the subsurface formation 26, and composition
of the
hydrocarbon content in the subsurface formation 26, can also influence
asphaltene
precipitation.
[318] In some implementations, when a substantially pure paraffinic solvent is
used as the
asphaltene-precipitating solvent 24, the extent of asphaltene precipitation
can be higher
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than when the asphaltene-precipitating solvent 24 includes a combination of
different
solvents, for instance a combination of a paraffinic solvent and a non-
paraffinic solvent,
such as an aromatic solvent (e.g., toluene, diesel, xylene). Combining
different solvents
to obtain the asphaltene-precipitating solvent 24 can be a useful approach to
leverage
advantages of the respective solvents. In implementations where the asphaltene-
precipitating solvent 24 includes steam, e.g., for a solvent-steam recovery
process, the
produced mobilized bitumen may also be deasphalted to a lesser extent, as less
solvent
may be injected into the reservoir, and mobilizing heat is being provided at
least in part by
the steam.
[319] The degree of deasphalting of the produced bitumen can also vary
depending on
the moment when the mobilized bitumen is produced during the operation of the
solvent-
assisted recovery process. For instance, when the mobilized bitumen is
produced shortly
after the startup stage, the solvent content can be lower than later on during
the normal
operation stage, and the degree of deasphalting of the produced mobilized
bitumen can
thus be lesser compared to the degree of deasphalting of produced mobilized
bitumen
obtained later on, after continued injection of the asphaltene-precipitating
solvent into the
subsurface formation. In other words, when the asphaltene-precipitating
solvent has been
injected over a longer period during the course of the normal operation stage,
the larger
solvent content in the extraction chamber can contribute to an increased
precipitation and
deposition of the asphaltenes within the subsurface formation.
[320] It is to be noted that a subsurface formation represents a partially
uncontrolled
environment, and certain characteristics of the subsurface formation can also
influence
the extent of in situ asphaltene precipitation and deposition that occurs
within the
subsurface formation. Each subsurface formation has its own characteristics,
for instance
with regard to the type of geological formation, the presence or absence of
water zone(s)
and/or of reservoir compartments, sedimentary facies, and the porosity and
geology of the
subsurface formation. In some implementations, appropriate subsurface
deasphalting
strategies taking into consideration the heterogeneity of the subsurface
formation can thus
be put in place such that the produced deasphalting bitumen is upgraded
according to
given criteria.
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[321] In addition, the composition of bitumen can vary depending on its
location in the
subsurface formation, for instance due to lateral variability, i.e., when the
bitumen is
located higher up in the formation than deeper in the formation, and can also
vary along
certain depositional breaks. Thus, depending on the location from which the
bitumen is
mobilized and drained to the production well (e.g., as the operation of the
well pair
operation progresses through time), deasphalting conditions can be adjusted to
once
again recover a produced deasphalted bitumen that is deasphalted according to
given
criteria.
[322] Still referring to Figure 1, a production fluid 28 is recovered at
surface and includes
a deasphalted bitumen fraction, water, solids and asphaltene-precipitating
solvent 24. The
production fluid 28 is then subjected to separation 48 to separate deasphalted
bitumen 54
from the production fluid 28.
[323] The separation 48 can be a single separation step or can include a
series of
separation steps. The separation 48 can be implemented for instance to
separate water,
solids, solvent, and/or non-condensable gas from the production fluid 28. The
solvent
separation can be useful to recover a portion of the asphaltene-precipitating
solvent 24
that has been previously introduced into the formation 26 for mobilizing and
deasphalting
the bitumen. The recovered solvent can then be reintroduced into the formation
26 to be
re-used as the asphaltene-precipitating solvent 24.
[324] With reference to Figures 1 and 2, a recycled asphaltene-precipitating
solvent
stream 50 is separated from the production fluid 28, and a stream comprising
water and
solids 52 is also recovered. Again, the separation 48 can include multiple
steps that
separate different components from the production fluid sequentially, for
example. The
separation 48 can leverage mechanisms such as gravity separation and
evaporative
separation to remove different components from each other.
[325] After the separation step 48, the deasphalted bitumen 54 is transported
to a thermal
treatment unit 56 to be thermally treated and produce the partially upgraded
bitumen
product 58. The separation 48 can be provided to obtain deasphalted bitumen
that has
desirable characteristics prior to being subjected to the thermal treatment
56, for instance
to obtain given proportions of certain components such that the thermal
treatment can be
CA 3042920 2019-05-10

47
optimized to obtain a partially upgraded bitumen product also having given
characteristics,
such as with regard to its pipelinability. The separation step 48 can thus be
controlled
based on desired properties of the deaspalted bitumen feedstock that is
supplied to the
thermal treatment 56.
[326] Still referring to Figure 1, the stream of deasphalted bitumen 54 is
then subjected to
the thermal treatment 56 at surface. In some implementations, the at-surface
thermal
treatment 56 using subsurface deasphalted bitumen 54 as an input stream may
benefit
from heightened control to account for the variability in the properties (P)
of the production
fluid 28 and in the deasphalted bitumen 54. For instance, as noted above, the
deasphalted
bitumen can have a variable asphaltene content, especially during the
transition from the
startup stage to the normal operation stage. One or more properties (P) of the
deasphalted
bitumen 54 can be measured and determined, and then the thermal treatment 56
can be
controlled accordingly. Control strategies can include controlling hydrogen
injection, pre-
treating or mixing the produced deasphalted bitumen product with other
hydrocarbon
streams, for instance to obtain a more consistent composition of the feedstock
subjected
to the thermal treatment, or regulating operating conditions of the thermal
treatment unit.
Possible control strategies are discussed in further detail below.
[327] With reference to Figure 2, in some implementations, the partially
upgraded bitumen
product 58 can be subjected to a dilution step 60, where a diluent 62 from a
diluent supply
64 is added to the partially upgraded bitumen product 58 to produce a diluted
bitumen
product 66. In some implementations, the diluted bitumen product 66 is diluted
so as to
meet pipeline specifications. Examples of diluents include a hydrotreated
naphtha or a
naphthenic diluent. The quantity of diluent that is added can be kept to a
minimum by
implementing the techniques described herein which provides an opportunity to
thermally
treat a subsurface deasphalted bitumen product at higher severity conditions
than whole
bitumen. For instance, in some implementations, the need for diluent addition
can be
reduced to between 10 vol.% to 20 vol.%, and even to less than about 10 vol.%
per
blended diluted bitumen barrel to meet pipeline specifications, compared to
about 35 vol.%
of diluent per blended diluted bitumen barrel for whole bitumen.
[328] With reference to Figure 3, in some implementations, the deasphalted
bitumen 54
can be further deasphalted if desired, i.e., the deasphalted bitumen 54 can be
subjected
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48
to an at-surface deasphalting step 68 to further precipitate asphaltenes. In
such
implementations, an asphaltene-precipitating solvent 70 from a solvent supply
72 is fed to
a solvent deasphalting unit, and a deasphalted bitumen 154 stream and an
asphaltenes-
enriched stream 74 are produced. The resulting deasphalted bitumen 154 can
then be
subjected to the thermal treatment 56. In some implementations, however, all
of the
desired level of deasphalting is performed in situ and no subsequent at-
surface
deasphalting is subsequently performed.
[329] In some implementations, the deasphalted bitumen 54 can be supplied as a
feed
stream continuously to the thermal treatment 56. The operating conditions of
the thermal
treatment 56 can be adjusted taking into consideration the properties of the
deasphalted
bitumen 54 being fed as a direct feed stream, for instance to a thermal
treatment unit. For
instance, the temperature and the pressure at which the thermal treatment unit
is
operated, and the residence time of the deasphalted material within the
thermal treatment
unit, are variables of the thermal treatment that can be adjusted. In one
implementation,
the output of the separation vessel that produces the deasphalted bitumen 54
can be
fluidly connected via pipeline to the input of the thermal treatment unit.
Alternatively, a
surge tank and appropriate pumping equipment can be provided along the
pipeline. The
feed line can be configured such that the thermal treatment unit receives only
the
deasphalted bitumen 54 as a feedstock.
[330] With reference now to Figure 4, the deasphalted bitumen 54 can
optionally be
subjected to a blending step 55 to obtain a combined deasphalted bitumen
material 57
that is fed to the thermal treatment 56. For instance, the deasphalted bitumen
54 can be
blended with a second hydrocarbon material 53 to obtain the combined
deasphalted
bitumen material 57. The second hydrocarbon material 53 can have a different
composition than the deasphalted bitumen 54. In some implementations, the
deasphalted
bitumen 54 is blended with a second hydrocarbon material 53 when the
deasphalted
bitumen 54 has a viscosity that is above or below a given viscosity threshold.
For instance,
the deasphalted bitumen 54 can be obtained from a formation that is at an
earlier stage of
operation, while the second hydrocarbon material 53 can be obtained from a
formation
that is at a later stage of operation, so as to obtain the combined
deasphalted bitumen
material 57. Thus, a stream with higher asphaltene content can be combined
with a stream
having lower asphaltene content. In such implementations, the combined
deasphalted
CA 3042920 2019-05-10

49
bitumen material 57 can have properties that result from the respective
properties of the
deasphalted bitumen 54 and the second hydrocarbon material 53.
[331] Properties (P) of various streams can be monitored and the measurements
can be
used for process control. For example, properties (P) of the deasphalted
bitumen 54 or of
the combined deasphalted bitumen material 57 subjected to the thermal
treatment 56 can
be monitored. Properties (P) of the partially upgraded bitumen product 58 can
also be
determined. Once these properties are analyzed and depending on the deviation
from
desired specifications, operating parameters of the thermal treatment 56 can
be controlled
using a controller 80 in order to thermally treat the feed material in such a
way that the
characteristics of the partially upgraded bitumen product 58 are within given
specifications.
Parameters of the thermal treatment 56 that can be adjusted include
temperature,
pressure and duration of the thermal treatment 56. In some implementations, a
separation
step 59 can also follow the thermal treatment 56 to separate the partially
upgraded
bitumen product 58, for instance, into a thermally treated heavy stream 61 and
a thermally
treated light stream 63.
[332] With reference now to Figure 5, in some implementations, the deasphalted
bitumen
54 can be directed to a holding tank 70, to allow a given volume of
deasphalted bitumen
54 to accumulate and be stored in the holding tank 70 prior to being fed to
the thermal
treatment 56. Storing a given volume of the deasphalted bitumen 54 that will
subsequently
be used as a feedstock for the thermal treatment step 56 can facilitate
monitoring the
properties of that given volume of deasphalted bitumen 54, and can also
facilitate
attenuating variations in the deasphalted bitumen stream 54 such that a more
uniform feed
to the thermal treatment 56 can be provided. Having a given volume of
deasphalted
bitumen 54 with known properties can facilitate the operation and/or
optimization of the
thermal treatment 56 taking into consideration these known properties. In such
implementations, benefits of conducting subsurface deasphalting such that
precipitated
asphaltenes remain within the subsurface formation can be combined with those
of
supplying a deasphalted product that has known and given characteristics to
thermal
treatment, thus facilitating operation of the thermal treatment 56 under
predetermined or
constant operating parameters instead of being reactive to variable
characteristics of a
continuous incoming stream of deasphalted bitumen 54. This approach can
contribute to
maintaining the performance of the thermal treatment 56.
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50
[333] Still referring to Figure 5, properties (P) of the deasphalted bitumen
54 stored in the
holding tank 70 can be monitored to obtain data on the properties of the
stored
deasphalted bitumen 71. The properties (P) of streams and materials upstream
of the
thermal treatment 56 can be used for feed-forward control of the thermal
treatment unit.
On the other hand, properties (P) of the partially upgraded bitumen product 58
can also
be monitored and can be used for feedback control. In fact, various feedback
and feed-
forward control strategies can be implemented.
[334] For instance, measurements that enable determining asphaltene content,
composition and viscosity of the stored deasphalted bitumen 71 and/or the
partially
upgraded bitumen product 58 can be obtained and analyzed. Once such
information is
available, feedback control adjustments 76 can be performed at relevant
locations such
that given characteristics of the stored deasphalted bitumen 71 and/or the
partially
upgraded bitumen product 58 can be obtained, for instance by adjusting
parameters of
the separation step 48, and/or by adjusting the addition of the second
hydrocarbon
material 53. Feedback control adjustments 76 can also be implemented to
control the
operating parameters of the thermal treatment 56 in accordance with the
properties of the
stored deasphalted bitumen 71 and/or the partially upgraded bitumen product
58.
Dilution of the thermally treated deasphalted bitumen stream
[335] Referring back to Figure 2, the partially upgraded bitumen product 54
can be
subjected to a dilution step 60 to produce a diluted bitumen product 66. The
partially
upgraded bitumen product 54 can be diluted to a predetermined pipeline
specification.
Examples of diluent include a hydrotreated naphtha or a naphthenic diluent.
[336] As mentioned earlier, the quantity of diluent added can be kept to a
minimum by
implementing the techniques described herein which provide an opportunity to
thermally
treat a subsurface deasphalted bitumen product at higher severity conditions
than whole
bitumen. For instance, in some implementations, the need for diluent addition
can be
reduced to about 10 vor/o per blended diluted bitumen barrel to meet pipeline
specifications, compared to about 35 vol.% of diluent per blended diluted
bitumen barrel
for whole bitumen. In some implementations, the need for diluent addition can
be reduced
CA 3042920 2019-05-10

51
to less than about 10 vol% per blended diluted bitumen barrel to meet pipeline
specifications.
Heat transfer and integration
[337] In some implementations, the heat generated during the thermal treatment
56 can
be used to pre-heat certain streams in an in situ processing facility. For
instance, the heat
generated during the thermal treatment 56 as described herein can be used to
preheat
the asphaltene-precipitating solvent 54 prior to its injection into the
subsurface formation.
This could be accomplished by feeding the recovered solvent and the hot
partially
upgraded bitumen through an indirect heat exchanger so that the partially
upgraded
bitumen can be cooled while the solvent is heated. The solvent can require
heating for
reinjection while the partially upgraded bitumen can require cooling prior to
storage. The
heat generated during the thermal treatment 56 can also be used to heat other
units,
streams or heat transfer fluids that are part of the in situ processing
facility.
[338] Although the process implementations as described herein and
corresponding parts
thereof have certain process configurations as explained and illustrated
herein, not all of
these components and process configurations are essential and thus should not
be taken
in their restrictive sense. It is to be understood that other suitable
components and
processing configurations can optionally be used for the process
implementations for
partially upgrading bitumen as described herein.
Control strategies ¨ adjusting operating conditions of the thermal treatment
[339] Figure 6 shows an example of a control strategy 200 for an
implementation of the
partial upgrading techniques combining subsurface deasphalting followed by
thermal
treatment as described herein. In this implementation of the control strategy
200, one
objective is to modulate the operating parameters of the thermal treatment to
take into
account possible variability in the properties of the deasphalted bitumen
being fed to the
thermal treatment, such that a partially upgraded bitumen product having given
characteristics can be obtained.
[340] The control strategy 200 includes the initial step of recovering
deasphalted bitumen
228 using an in situ solvent-assisted recovery process. The deasphalted
bitumen can
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52
optionally be subjected to a blending step and/or a separating step 230. The
blending step
can include blending together the deasphalted bitumen with one or more
hydrocarbon
materials to obtain a combined deasphalted material, the combined deasphalted
material
having a desired property such as a given asphaltene content. A separation
step can be
implemented to separate solvent from the deasphalted bitumen. It is noted that
other
components, such as water and solids, are removed from the production fluid to
produce
the deasphalted bitumen. When solvent is separated from the deasphalted
bitumen, the
recovered solvent can be re-used as the asphaltene-precipitating solvent to be
reintroduced into the subsurface formation.
[341] The deasphalted bitumen, optionally following the blending and/or
separation step
230, is then subjected to a mild thermal treatment 232, for instance in a
thermal treatment
unit, at given operating conditions to produce a partially upgraded bitumen
product. The
partially upgraded bitumen product is removed 234 from the thermal treatment
unit, either
as a single stream or as one of multiple streams, and one or more
characteristics of the
partially upgraded bitumen product are determined 236. Example characteristics
of the
partially upgraded bitumen product that can be determined can relate to its
pipelinability,
such as its viscosity, density and composition.
[342] If it is determined that the partially upgraded bitumen product is
suitable for pipeline
transport or that the characteristics of the partially upgraded bitumen
product meet a
predetermined specification, it can be decided that the thermal treatment can
continue to
operate according to similar operating conditions unless a significant change
were to occur
upstream of the thermal treatment. On the other hand, if it is determined that
the partially
upgraded bitumen product is not suitable for pipeline transport or that its
characteristics
do not meet a predetermined specification, the operating conditions of the
thermal
treatment can be modified accordingly 238.
[343] Changes that can be made to the operation of the thermal treatment
include
adjusting the temperature and/or pressure at which it is conducted and
adjusting the
duration of the thermal treatment. Another option is to proceed with a
separation step 242
to recover a thermally treated light stream and a thermally treated heavy
stream.
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53
[344] Yet another option, for instance if it is determined that the amount of
coke formed
during the thermal treatment is above a certain threshold, is to perform the
thermal
treatment in the presence of a hydrogen transfer agent or an external source
of hydrogen
240 to delay the onset of coke formation. A hydrogen transfer agent as
described herein
refers to agents that can be added to be present during the thermal treatment
to inhibit
coke formation and encourage hydrogen transfer, for instance from the heavy
fraction to
the light fraction. Hydrogen transfer agents can have the effect of increasing
the time and
temperature conditions at which incipient coking begins, thus enabling longer
residence
times or higher temperatures while still inhibiting coke formation. Such
agents can be, for
instance, methane, propane, butane and anthracene. Among possible hydrogen
transfer
agents are a class of compounds referred to as hydrogen donors. These hydrogen
donors
are able to donate hydrogen atoms to other compounds. Examples of hydrogen
donors
include, for instance, compounds such as tetralin, decalin, light crude oil,
synthetic crude
oil and fractions thereof, shale oil and tight oil. For clarity, it should be
noted that hydrogen
transfer agents, including hydrogen donors, are considered distinct from what
is referred
to herein as an external source of hydrogen, such as diatomic hydrogen (H2)
containing
gas.
[345] In some implementations, the presence of some asphaltenes in the
deasphalted
bitumen can facilitate the transfer of hydrogen from the heavy fraction to a
lighter fraction
during thermal treatment, and can help reduce or avoid the rejection of
hydrogen as part
of a non-condensable gas phase product. This hydrogen transfer can reduce or
eliminate
the amount of external diatomic hydrogen addition required to achieve target
quality
specifications of the thermally treated bitumen product, such as the product's
viscosity,
density and olefin content. Thus, in some implementations, it can be desirable
to keep a
certain level of asphaltenes in the deasphalted bitumen that is produced such
that these
asphaltenes can contribute to the transfer of hydrogen from the heavy fraction
to the lighter
fraction.
[346] In some implementations, the addition of an external source of hydrogen
is not
required to achieve target quality specifications of the partially upgraded
bitumen product.
This is in contrast with typical thermal processes, in which significant
cracking of the
bitumen stream occurs, resulting in chemically bonded hydrogen in the bitumen
feedstock
being rejected to the gas phase. Consequently, in typical thermal processes,
the liberation
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54
of hydrogen within a high hydrogen content non-condensable gas (e.g., a gas
phase
including diatomic hydrogen and methane) typically results in a hydrogen-to-
carbon ratio
in the thermally cracked liquid hydrocarbon product that is lower than or
comparable to
the hydrogen-to-carbon ratio of the feed. Lower hydrogen-to-carbon ratios is
not desirable
since one objective of partial upgrading is to increase the hydrogen-to-carbon
ratio of the
product. Thus, in some implementations, the operating conditions of the
thermal treatment
are chosen such that a balance is found between hydrogen transfer and thermal
cracking
of the hydrocarbons, while avoiding or minimizing external hydrogen addition,
coking
and/or olefin formation.
[347] Of course, any other parameters that can influence the characteristics
of the output
stream recovered following the thermal treatment can be contemplated such that
the
thermal treatment can be adapted to produce a partially upgraded bitumen
product
suitable for pipeline transport. Once the partially upgraded bitumen product
is determined
to have desired properties, the partially upgraded bitumen product can be
supplied to
pipelining or storage 244.
Control strategies ¨ Adjusting properties of deasphalted bitumen
[348] Figure 7 shows an example of another control strategy 300 for the
implementation
of the partial upgrading techniques combining subsurface deasphalting followed
by a
thermal treatment as described herein. In this implementation of the control
strategy 300,
one objective is to characterize the properties of the deasphalted bitumen and
to modify
these properties upstream of the thermal treatment so as to reduce the
variability in the
operating parameters of the subsequent thermal treatment. Modifying the
properties of the
deasphalted bitumen can include directly modifying the characteristics of the
deasphalted
bitumen, such as composition by blending different streams together, and/or
adjusting the
operating parameters of the subsurface deasphalting process.
[349] The control strategy 300 includes the initial step of recovering
deasphalted bitumen
328 using a solvent-assisted recovery process. The deasphalted bitumen can
then be
characterized in a characterizing step 330 to determine various properties of
the
deasphalted bitumen, e.g., density, viscosity, composition, and so on. If the
properties of
CA 3042920 2019-05-10

55
the deasphalted bitumen are determined to be desirable, the deasphalted
bitumen can be
subjected to the thermal treatment 336.
[350] If the properties of the deasphalted bitumen are not desirable or are
not within a
predetermined operating window, then these properties can be directly adjusted
in a
blending and/or separation step 332. If a solvent separation step is
performed, the
recovered solvent 342 can be re-used as the asphaltenes-precipitation solvent
to be
reinjected into the subsurface formation. For example, solvent recovery from
the
deasphalted bitumen can be adjusted to recover more or less solvent. Blending
can be
performed to adjust the asphaltene content or other properties.
[351] In addition, if the properties of the deasphalted bitumen are not
desirable, a variable
related to the subsurface deasphalting can be adjusted 334, such as the type
or
composition of the asphaltene-precipitating solvent introduced in the
subsurface
formation, adjusting the solvent-to-bitumen ratio, adjusting the downhole
temperature,
adjusting the solvent injection rate, and so on. For example, if lower
asphaltene levels in
the deasphalted bitumen are desired, then the in situ conditions can be
modified (e.g., by
using a solvent that has a higher tendency to precipitate asphaltenes at
certain solvent-
to-bitumen ratios, injecting solvent at higher rates into the formation, or
changing the heat
that is provided to the formation via the solvent or downhole heaters) in
order to increase
in situ precipitation and therefore decrease the asphaltene content in the
deasphalted
bitumen.
[352] Once it is determined that the deasphalted bitumen has the desired
properties, the
deasphalted bitumen is subjected to the thermal treatment 336, for instance in
a thermal
treatment unit, to produce the partially upgraded bitumen product. The
partially upgraded
bitumen product then undergoes a removal step 340 from the thermal treatment
unit.
Depending on the type of thermal treatment unit that is used, the removal step
can take
various forms. In some implementations, the removal step 340 is performed such
that
substantially all of the content of the thermal treatment unit is removed as a
single stream
that forms the partially upgraded bitumen product. Alternatively, two separate
streams can
be removed from the thermal treatment unit, e.g., a liquid phase underflow
stream that
constitutes the partially upgraded bitumen product (which can also be referred
to as a gas-
depleted partially upgraded bitumen product), and an overhead vapour phase
stream that
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56
includes vapours and non-condensable gas components. The partially upgraded
bitumen
product can then be supplied for pipelining or storage 342.
[353] Optionally, the partially upgraded bitumen product or the gas-depleted
partially
upgraded bitumen product can be subjected to a separation step 344, which can
include
separation in a flash column for example, to separate a thermally treated
light fraction
(including for instance distillate, gasoil and naphtha components), from a
thermally treated
heavy fraction. It is to be understood that when referring to this separation
step, it can
include a plurality of separation stages and units. For example, the plurality
of separation
steps could include a flash column followed by a fractionation column that
receives the
bottoms of the flash column, and then a vacuum distillation column that
receives the
bottoms of the fractionation column. Other arrangements of flash vessels,
fractionation
columns and distillation columns for separating the thermally treated stream
into different
output streams can also be implemented.
[354] In summary, the series of steps shown in Figure 7 illustrates
implementations where
characteristics of the deasphalted bitumen upstream of the thermal treatment
can be
adjusted to attain or maintain given properties of the deasphalted bitumen
that is fed to
the thermal treatment unit, such that the thermal treatment unit is operated
according to a
given set of conditions that can remain substantially constant at least for a
given period of
time. In contrast, in Figure 6, it is the operating conditions of the thermal
treatment that
can be adjusted to take into account the variability in the properties of the
deasphalted
bitumen derived from the in situ recovery operation that includes subsurface
deasphalting.
[355] Although Figures 6 and 7 are presented as distinct control strategies,
it is to be
understood that both control strategies can be used and combined to further
enhance
control options, for instance in circumstances where there may be notable
variability. This
scenario can be envisioned for instance when the recovery process evolves over
time,
especially during transition from start-up operations to regular operations,
and during
transition from regular operations to mature or wind-down operations of the in
situ bitumen
recovery process.
[356] Referring now to Figure 8, an example implementation of the thermal
treatment and
downstream processing will be described. The deasphalted bitumen feedstock 454
can
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be supplied to the thermal treatment unit 456, which can include a pre-heater
458 that can
be a direct-fired heater for heating the feedstock to a desired temperature.
The thermal
treatment unit 456 can also include a soaker tank 460 that receives the
preheated
feedstock and maintains the material at desired pressure conditions for a
certain treatment
time. The soaker tank 460 can be configured depending on the desired
temperature and
pressure conditions. The soaker tank 460 can be a relatively simple unit that
does not
include any heaters or the like for inputting additional heat into the
feedstock, but rather
maintains the general temperature of the material. The soaker tank 460 can be
equipped
with a heating jacket to insulate the tank and minimize heat loss.
[357] The partially upgraded bitumen product 462 is then withdrawn from the
soaker tank
460 and can be supplied to downstream separation vessels. For example, as
illustrated in
Figure 8, the partially upgraded bitumen product 462 can be fed to a primary
separation
vessel 464 that can be a flash tank to produce a vapour stream 466 and a
liquid stream
468. The vapour stream can include C3 and C4 hydrocarbons that can be used as
fuel, for
example in the pre-heater 458. The liquid stream 468 includes the heavier
hydrocarbons
and can be supplied into a secondary separation vessel 470 which can be a
fractionation
column equipped with a reflux unit 472 and a reboiler 474. The fractionation
column can
produce various output stream depending on its design. For example, the
fractionation
column can produce a naphtha overhead stream 476, a gas oil side draw stream
478, and
a heavy hydrocarbon bottom stream 480. Alternatively, the fractionation column
could
have only two output streams: a bottoms and an overhead. The naphtha overhead
stream
476 can be used in various applications as diluent.
[358] The heavy hydrocarbon bottom stream 480 can be considered a product
stream or
can be subjected to further processing depending on its composition. For
example, if the
feedstock 454 is substantially or fully deasphalted, then the resulting heavy
hydrocarbon
bottom stream 480 can be handled as a hot bitumen product and can thus be
cooled and
supplied to storage or can be diluted for pipelining. If the feedstock
contains a notable
concentration of asphaltenes, then the heavy hydrocarbon bottom stream 480 can
be
subjected to solvent deasphalting (SDA) 482 to produce a solvent diluted
bitumen 484 and
a solvent rich asphaltene stream 486, both of which are subjected to solvent
recovery to
respectively produce a deasphalted oil product 488 and an asphaltene rich
residue 490
that can be disposed of or further processed.
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58
[359] Still referring to Figure 8, in some implementations, a hydrogen and/or
a transfer
agent stream 492 can be added to the bitumen feedstock upstream of the pre-
heater 458.
In addition, a recycled oil stream 494 can be added to the feedstock 454
upstream of the
pre-heater 458. The recycled oil can be obtained from downstream sources that
are part
of the overall process, such as from the deasphalted oil product 488 or the
heavy
hydrocarbon bottom stream 480.
[360] While the thermal treatment and downstream processing systems described
in
relation to Figure 8 can be used in combination with the in situ deasphalting
processes
described herein, it is also noted that alternative systems, processes and
equipment can
also be used. For example, various types of vessel designs can be used for the
pre-heater
(e.g., direct fired or indirect heat exchanger). In addition, alternatives to
the soaker tank
can also be used, such as reaction vessels having certain configurations and
designs,
having integrated heater distributed within the vessel to maintain certain
heating
characteristics, and the like. Furthermore, downstream separation systems can
include
various designs for separating the partially upgraded bitumen product 462 into
desired
hydrocarbon streams for sale or addition into other parts of the process. When
the thermal
treatment unit is controlled based on the in situ process, it is noted that
one or more of the
various pieces of equipment can be controlled to obtain the desired outcome.
For example,
heating enables by the pre-heater, residence time in the soaker tank, the
addition of
hydrogen or a transfer agent, and/or the addition of recycled oil could be
controlled in
response to measured characteristics of the in situ process.
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Representative Drawing