Note: Descriptions are shown in the official language in which they were submitted.
CA 02956736 2017-02-01
PROCESSES FOR TREATING RESERVOIR FLUID COMPRISING MATERIAL
PRODUCED FROM A HYDROCARBON CONTAINING RESERVOIR
FIELD
[0001] The present disclosure relates to recovery and reuse of water from
reservoir fluid
comprising material produced from a hydrocarbon containing reservoir.
BACKGROUND
[0002] Some hydrocarbon production processes, such as Steam-Assisted
Gravity Drainage
("SAGD"), inject steam into a hydrocarbon-containing reservoir to stimulate
production of
hydrocarbons. SAGD uses a pair of wells to produce a hydrocarbon from a
hydrocarbon
containing reservoir. Typically the well pair includes two horizontal wells
vertically spaced
from one another, with the upper well used to inject steam into the reservoir
and the lower well
to produce the hydrocarbon. The steam operates to generate a steam chamber in
the reservoir,
and thermal heat from the steam operates to lower the viscosity of the
hydrocarbon, allowing for
gravity drainage, and thereby production from the production well. The
produced fluids
typically include a mixture of hydrocarbons and water, the water resulting
from the condensing
of the steam (referred to as "produced water").
[0003] For economic and environmental reasons, it is desirable to recycle
the produced
water. Typically, the produced water is treated to remove, amongst other
things, oils and solids,
and then converted into steam using a steam generator.
[0004] The internal energy of produced fluids is not insignificant.
However, such energy is
not being optimally used to drive existing treatment processes.
SUMMARY
[0005] In one aspect, there is provided a process for treating a reservoir
fluid-comprising
mixture, comprising: producing a reservoir fluid-comprising mixture, including
oil and water,
from a hydrocarbon containing reservoir; at a pressure that is greater than
atmospheric pressure,
separating an oil-lean mixture from the reservoir fluid-comprising mixture
such that the
concentration of oil within the oil-lean mixture is greater than 10 ppin; at a
pressure that is
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greater than atmospheric pressure, effecting separation, from the oil-lean
mixture, of a scale
forming-lean liquid and a scale forming-rich material, by evaporation or
ceramic membrane
filtration; producing pressurized steam from the scale forming-lean liquid
using a steam
generator; and supplying the pressurized steam to the hydrocarbon containing
reservoir for
effecting mobilization of hydrocarbons within the hydrocarbon containing
reservoir.
[0006] In another aspect, there is provided a process for treating a
reservoir fluid-comprising
mixture, comprising: producing the reservoir fluid-comprising mixture,
including oil and water,
from a hydrocarbon-containing reservoir; at a pressure that is greater than
atmospheric pressure,
separating an oil-lean mixture from the reservoir fluid-comprising mixture; at
a pressure that is
greater than atmospheric pressure, separating a scale forming-lean liquid and
a scale forming-
rich material from the oil-lean mixture, by at least one of evaporation, ion-
exchange, softening
and membrane filtration; producing pressurized steam from the scale forming-
lean liquid using a
steam generator; and supplying the pressurized steam to the hydrocarbon
containing reservoir for
effecting mobilization of hydrocarbons within the hydrocarbon containing
reservoir.
[0007] In some implementations, the process further comprises, prior to
producing the
pressurized steam, supplying the scale forming-lean liquid to a tank, wherein
the tank is disposed
at a pressure that is greater than atmospheric pressure.
[0008] In some implementations, the concentration of oil within the oil-
lean mixture is
between 10 ppm and 250 ppm.
[0009] In some implementations, the concentration of oil within the oil-
lean mixture is
between 10 ppm and 100 ppm.
[0010] In some implementations, the concentration of oil within the oil-
lean mixture is
between 10 ppm and 30 ppm.
100111 In some implementations, the pressure is at least 20 kPa above
atmospheric pressure.
[0012] In another aspect, there is provided a process for treating a
reservoir fluid-comprising
mixture, being produced through a wellhead from a hydrocarbon containing
reservoir,
comprising: fluidically coupling the wellhead to a steam generator via a fluid
passage of a fluid
conductor; producing, through a wellhead, a reservoir fluid-comprising
mixture, including oil
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and water, from a hydrocarbon containing reservoir; separating an oil-lean
mixture from the
reservoir fluid-comprising mixture; supplying the oil-lean mixture to a scale-
forming solids
separator, wherein the scale-forming solids separator includes an evaporator
or a ceramic
membrane filtration unit; separating, from the oil-lean mixture, a scale
forming-lean liquid and a
scale forming-rich material, using the scale forming solids separator; such
that each one of (i) the
separating of the oil-lean mixture from the reservoir fluid-comprising
mixture, (ii) the supplying
of the oil-lean mixture to the scale forming solids separator, and (iii) the
separating, from the oil-
lean mixture, of a scale forming-lean liquid and a scale forming-rich
material, using the scale
forming solids separator is effected within the fluid passage, and the
entirety of the fluid passage
is disposed at a pressure that is greater than atmospheric pressure; producing
pressurized steam
from the scale forming-lean liquid using the steam generator; and supplying
the pressurized
steam to the hydrocarbon containing reservoir to effect mobilization of
hydrocarbons within the
hydrocarbon containing reservoir.
[00131 In
yet another aspect, there is provided a process for treating a reservoir fluid-
comprising mixture, comprising: producing, through a wellhead, the reservoir
fluid-comprising
mixture, including oil and water, from a hydrocarbon-containing reservoir;
fluidically coupling
the wellhead to a steam generator via a fluid passage of a fluid conductor;
separating an oil-lean
mixture from the reservoir fluid-comprising mixture such that the oil-lean
mixture has an oil
concentration which is greater than 10 ppm; supplying the oil-lean mixture to
a scale-forming
solids separator, wherein the scale-forming solids separator includes at least
one of an
evaporator, an ion-exchange unit, a softening unit and a membrane filtration
unit operation;
separating, from the oil-lean mixture, a scale forming-lean liquid and a scale
forming-rich
material, using the evaporator; such that each one of (i) the separating of
the oil-lean mixture
from the reservoir fluid-comprising mixture, (ii) the supplying of the oil-
lean mixture to the
evaporator, and (iii) the separating, from the oil-lean mixture, of a scale
forming-lean liquid and
a scale forming-rich material, using the evaporator is effected within the
fluid passage, and the
entirety of the fluid passage is disposed at a pressure that is greater than
atmospheric pressure;
producing pressurized steam from the scale forming-lean liquid using the steam
generator; and
supplying the pressurized steam to the hydrocarbon containing reservoir to
effect mobilization of
hydrocarbons within the hydrocarbon containing reservoir.
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[0014] In some implementations, the process further comprises, prior to
producing the
pressurized steam, supplying the scale forming-lean liquid to a tank, wherein
the tank is disposed
at a pressure that is greater than atmospheric pressure.
[0015] In some implementations, he concentration of oil within the oil-lean
mixture is
between 10 ppm and 250 ppm.
[0016] In some implementations, the concentration of oil within the oil-
lean mixture is
between 10 ppm and 100 ppm.
100171 In some implementations, the concentration of oil within the oil-
lean mixture is
between 10 ppm and 30 ppm.
[0018] In some implementations, the pressure is at least 20 kPa above
atmospheric pressure.
[0019] In another aspect, there is provided a process for treating a
reservoir fluid-comprising
mixture, comprising producing a reservoir fluid-comprising mixture, including
oil and water,
from a hydrocarbon containing reservoir; at a pressure that is greater than
atmospheric pressure,
separating an oil-lean mixture from the reservoir fluid-comprising mixture; at
a pressure that is
greater than atmospheric pressure, effecting separation, from the oil-lean
mixture, of a scale
forming-lean liquid and a scale forming-rich material; supplying the scale
forming-lean liquid to
a tank that is disposed at a pressure that is greater than atmospheric
pressure; supplying the scale
forming-lean liquid from the tank to a steam generator; producing pressurized
steam from the
scale forming-lean liquid using the steam generator; and supplying the
pressurized steam to the
hydrocarbon containing reservoir to effect mobilization of oil within the
hydrocarbon containing
reservoir.
[0020] In some implementations, the temperature of the scale forming-lean
liquid within the
tank is greater than 100 degrees Celsius.
100211 In some implementations, the separation, from the oil-lean mixture,
of a scale
forming-lean liquid and a scale forming-rich material, is effected by
evaporation.
[0022] In some implementations, the separation from the oil-lean mixture,
of a scale
forming-lean liquid and a scale forming-rich material, is effected by
pressurized hot lime
softening,
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[0023] In some implementations, the separation, from the oil-lean mixture,
of a scale
forming-lean liquid and a scale forming-rich material, is effected by ceramic
membrane
filtration.
[0024] In some implementations, the pressure is at least 20 kPa above
atmospheric pressure.
100251 In another aspect, there is provided a process for treating a
reservoir fluid-comprising
mixture, being produced through a wellhead from a hydrocarbon containing
reservoir,
comprising: fiuidically coupling the wellhead to a steam generator via a fluid
passage of a fluid
conductor; producing, through a wellhead, a reservoir fluid-comprising
mixture, including oil
and water, from a hydrocarbon containing reservoir; separating an oil-lean
mixture from the
reservoir fluid-comprising mixture; supplying the oil-lean mixture to a scale
forming solids
separator; separating, from the oil-lean mixture, a scale forming-lean liquid
and a scale forming-
rich material, using the scale forming solids separator; supplying the scale
forming-lean liquid to
a tank that is disposed at a pressure that is greater than atmospheric
pressure; supplying the scale
forming-lean liquid from the tank to a steam generator; such that each one of
(i) the separating of
the oil-lean mixture from the reservoir fluid-comprising mixture, (ii) the
supplying of the oil-lean
mixture to the scale forming solids separator, (iii) the separating, from the
oil-lean mixture, of a
scale forming-lean liquid and a scale forming-rich material, using the scale
forming solids
separator, (iv) the supplying of the scale forming-lean liquid to a tank that
is disposed at a
pressure that is greater than atmospheric pressure, and (v) the supplying of
the scale forming-
lean liquid from the tank to the steam generator is effected within the fluid
passage, and the
entirety of the fluid passage is disposed at a pressure that is greater than
atmospheric pressure;
producing pressurized steam from the scale forming-lean liquid using the steam
generator; and
supplying the pressurized steam to the hydrocarbon containing reservoir to
effect mobilization of
hydrocarbons within the hydrocarbon containing reservoir.
[0026] In some implementations, the temperature of the scale forming-lean
liquid within the
tank is greater than 100 degrees Celsius.
[0027] In some implementations, the separation, from the oil-lean mixture,
of a scale
forming-lean liquid and a scale forming-rich material, is effected by
evaporation.
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[0028] In some implementations, the separation from the oil-lean mixture,
of a scale
forming-lean liquid and a scale forming-rich material, is effected by
pressurized hot lime
softening,
[0029] In some implementations, the separation, from the oil-lean mixture,
of a scale
forming-lean liquid and a scale forming-rich material, is effected by ceramic
membrane
filtration.
[0030] In some implementations, the pressure is at least 20 kPa above
atmospheric pressure.
[0031] In another aspect, there is provided a process for treating a
reservoir fluid-comprising
mixture, being produced through a wellhead from a hydrocarbon containing
reservoir,
comprising: fluidically coupling the wellhead to a steam generator via a fluid
passage of a fluid
conductor; producing, through a wellhead, a reservoir fluid-comprising
mixture, including oil
and water, from a hydrocarbon containing reservoir; separating an oil-lean
mixture from the
reservoir fluid-comprising mixture; supplying the oil-lean mixture to a scale
forming solids
separator including at least one of an evaporator, an ion-exchange unit, a
softening unit and a
membrane filtration unit; separating, from the oil-lean mixture, a scale
forming-lean liquid and a
scale forming-rich material, using the scale forming solids separator; such
that each one of (i) the
separating of the oil-lean mixture from the reservoir fluid-comprising
mixture, (ii) the supplying
of the oil-lean mixture to the scale forming solids separator, and (iii) the
separating, from the oil-
lean mixture, of a scale forming-lean liquid and a scale forming-rich
material, using the scale
forming solids separator is effected within the fluid passage, and the
entirety of the fluid passage
is disposed at a pressure that is greater than atmospheric pressure; producing
pressurized steam
from the scale forming-lean liquid using the steam generator; and supplying
the pressurized
steam to the hydrocarbon containing reservoir to effect mobilization of
hydrocarbons within the
hydrocarbon containing reservoir.
[0032] In some implementations, the pressure is at least 20 kPa above
atmospheric pressure.
[0033] In some implementations, the process further comprises progressively
reducing
pressure along a section of the fluid passage, from downstream of the wellhead
to the evaporator.
100341 In another aspect, there is provided a process for treating a
reservoir fluid-comprising
mixture, being produced through a wellhead from a hydrocarbon containing
reservoir,
comprising: fluidically coupling the wellhead to an evaporator via a fluid
passage of a fluid
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conductor extending upstream from the evaporator; producing, through a
wellhead, a reservoir
fluid-comprising mixture, including oil and water, from a hydrocarbon
containing reservoir;
separating an oil-lean mixture from the reservoir fluid-comprising mixture;
supplying the oil-
lean mixture to the evaporator; separating, from the oil-lean mixture, an
aqueous liquid distillate
and a scale forming-rich material, using the evaporator; such that each one of
(i) the separating
of the oil-lean mixture from the reservoir fluid-comprising mixture, (ii) the
supplying of the oil-
lean mixture to the evaporator, and (iii) the separating, from the oil-lean
mixture, of an aqueous
liquid distillate and a scale forming-rich material, using the evaporator is
effected within the
fluid passage, and the entirety of a section of the fluid passage, that is
upstream of the
evaporator, is disposed at a temperature of at least (i.e. greater than or
equal to) the boiling point
temperature of the oil-lean mixture at the pressure within the evaporator;
producing pressurized
steam from the aqueous liquid distillate using the steam generator; and
supplying the pressurized
steam to the hydrocarbon containing reservoir to effect mobilization of
hydrocarbons within the
hydrocarbon containing reservoir.
[0035] In some implementations, the temperature is at least the boiling
point temperature of
water at 20 kPa above atmospheric pressure.
[0036] In some implementations, the process further comprises, after the
separating, from the
oil-lean mixture, a scale forming-lean liquid and a scale forming-rich
material, using the
evaporator, and prior to the producing pressurized steam from the scale
forming-lean liquid using
the steam generator, cooling the reservoir fluid-comprising mixture with the
scale forming-lean
liquid.
[0037] In some implementations, the effected cooling is such that the oil-
lean mixture has a
temperature of at least the boiling point temperature of the oil-lean mixture
at the pressure within
the evaporator.
[0038] In some implementations, the effected cooling is such that the oil-
lean mixture has a
temperature of at least the boiling point temperature of water at 20 kPa above
atmospheric
pressure.
[0039] In some implementations, the effected cooling is such that the
temperature of the
cooled reservoir fluid-comprising mixture is such that the specific gravity of
water, within the
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cooled reservoir fluid-comprising mixture, is greater than the specific
gravity of oil, within the
cooled reservoir fluid-comprising mixture, by a difference of between 20 kg/m3
and 70 kg/m3.
[0040] In some implementations, the temperature of the aqueous liquid
distillate is greater
than 100 degrees Celsius.
[0041] In some implementations, the process further comprises,
progressively reducing
temperature along the section of the fluid passage, from downstream of the
wellhead to the
evaporator.
[0042] In some implementations, the hydrocarbon containing reservoir is an
oil sands
reservoir.
BRIEF DESCRIPTION OF DRAWINGS
[0043] The preferred embodiments will now be described with the following
accompanying
drawings, in which:
[0044] Figure 1 is a schematic illustration of a well pair in an oil sands
reservoir for
implementation of a steam-assisted gravity drainage process;
[0045] Figure 2 is a process flow diagram illustrating a system for
practising an embodiment
of the process described herein.
DETAILED DESCRIPTION
[0046] Referring to Figures 1 and 2, there is provided a system 100 for
recovering and
reusing water contained within a reservoir fluid-comprising mixture 110 that
is produced from a
hydrocarbon-containing reservoir 30. The recovered water is converted to high
pressure steam
200 and conducted into the hydrocarbon-containing reservoir for effecting
production of
hydrocarbons from the reservoir. Amongst other things, the processes employed
within the
system are configured to minimize energy losses from the water being
recovered, and thereby
reduce energy requirements for converting the recovered water into steam with
a steam generator
190. In this respect, in sonic implementations, the process is carried out at
a pressure that is
greater than atmospheric pressure. In some implementations, the pressure is at
least 20 l(Pa above
atmospheric pressure.
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100471 For illustrative purposes below, an oil sands reservoir from which
bitumen is being
produced using Steam-Assisted Gravity Drainage ("SAGD") is described. However,
it should be
understood, that the techniques described could be used in other types of
hydrocarbon containing
reservoirs and/or with other types of thermal recovery methods that use steam.
[0048] The reservoir fluid-comprising mixture 110 is produced from an oil
sands reservoir
using a SAGD well pair. Referring to Figure 1, in a typical SAGD well pair,
the wells are
spaced vertically from one another, such as wells 10 and 20, and the
vertically higher well, i.e.,
well 10, is used for steam injection the SAGD operation, and the lower well,
i.e., well 20, is used
for producing bitumen. During the SAGD operation, steam injected through the
well 10
(typically referred to as the "injection well") is conducted into the
reservoir 30. The injected
steam mobilizes the bitumen within the oil sands reservoir 30. The mobilized
bitumen and steam
condensate drains through the interwell region 15 by gravity to the well 20
(typically referred to
as the "production well"), collects in the well 20, and is surfaced through
tubing or by artificial
lift to the surface, where it is produced through a wellhead 25.
[0049] The reservoir fluid-comprising mixture 110 includes oil and water.
In some
embodiments, for example, the reservoir fluid-comprising mixture 110 has a
temperature
between 150 degrees Celsius and 250 degrees Celsius. The pressure of the
reservoir fluid-
comprising mixture 110 can range from 1000 ¨ 4000 kPa (gauge), and is
dependent on the
pressure within the reservoir 30.
[0050] In some embodiments, for example, the reservoir fluid-comprising
mixture 110 is
conditioned, prior to separation into its material components, to produce a
treated reservoir fluid-
comprising mixture. For example, conditioning of the reservoir fluid-
comprising mixture 110
can includes cooling of the reservoir fluid-comprising mixture 110.
[00511 Downstream separation processes effect separation of an oil-lean
mixture 120 from
the reservoir fluid-comprising mixture 110 (see below), and, in some
embodiments, for example,
such separation processes are temperature dependent. Temperature affects both
density and
viscosity, and both of these parameters affect separation efficiency. To
improve such separation,
the reservoir fluid-comprising mixture 110 may be cooled prior to effecting
the separation. In
cases where the fluid temperature of the reservoir fluid-comprising mixture
110 is relatively low
(such as, for example, 165 degrees Celsius or less), limited or no cooling may
be required.
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[0052] In some embodiments, the temperature of the cooled reservoir fluid-
comprising
mixture 110 is such that the specific gravity of water, within the cooled
reservoir fluid-
comprising mixture 110, is greater than the specific gravity of oil, within
the cooled reservoir
fluid-comprising mixture 110, by a difference of between 20 kg/m3 and 70
kg/m3.
[0053] In some embodiments, the conditioning of the reservoir fluid-
comprising mixture
110 includes admixing diluent 220 with the reservoir fluid-comprising mixture.
The admixing of
the diluent 220 enables transport of the recovered oil through a pipeline. The
diluent also affects
the separation of an oil-lean mixture 120 from the cooled reservoir fluid-
comprising mixture 110.
The more diluent that is added, the greater the density difference between the
diluted oil and the
water. Diluent is expensive and there are some losses to the gas phase.
Accordingly, diluent
addition is minimized and limited to what is required such that the diluted
oil meets the sales
pipeline specifications. In some embodiments, the treating may include both
cooling of the
reservoir fluid-comprising mixture and admixing of the reservoir fluid-
comprising mixture with
diluent, in any order.
100541 In other embodiments, instead of cooling the reservoir fluid-
comprising mixture 110,
the conditioning of the reservoir fluid-comprising mixture 110 includes
heating the reservoir
fluid-comprising mixture 110 such that the density of oil becomes sufficiently
greater than the
density of water so as to enable a desired separation of an oil-lean mixture
120 from the reservoir
fluid-comprising mixture 110. In this case, no diluent is added. In some
implementations, the
separation of an oil-lean mixture 120 from the heated reservoir fluid-
comprising mixture 110 is
effected at about a temperature of 225 degrees Celsius.
[0055] The oil-lean mixture 120 is separated from the reservoir fluid-
comprising mixture 110
(conditioned or unconditioned) within an oil separator 138. In some
embodiments, in separating
the oil-lean mixture 120 from the reservoir fluid-comprising mixture 110, an
oil-rich mixture 130
becomes separated from the oil-lean mixture 120. In some embodiments, the oil
separator 138
includes three stages 140, 150, and 155. Typically, separation in stages 140
and 150 is effected
by gravity separation, while separation in stage 155 functions to provide
final polishing after the
gravity separation to effect production of the oil-lean mixture 120. The total
number of stages
being determined based on a desired separation efficiency, while in keeping
with a desire to
optimize utilization of capital.
CA 02956736 2017-02-01
[0056] In some embodiments, the stage 150 is effected within a vessel
including electrostatic
grids to assist in the separation. In some embodiments, the stage 150 may not
necessarily be
effected within a vessel, but rather a separation device that uses accelerated
gravity forces, such
as a hydrocyclone or a centrifuge. In some embodiments, the stages 140 and 150
may be
combined into a single stage.
[0057] The heavier liquid phase products 142, 152, generated from,
respectively, stages 140,
150, are combined into an intermediate oil-lean mixture 118. The oil-rich
mixture 130 is
conducted to a product holding tank 160. Gaseous material 144, 154, produced
from,
respectively, stages 140, 150, is managed by a vapour handling system.
100581 The intermediate oil-lean mixture 118 is supplied to a de-oiling
separator 155 for
effecting separation of an oil-rich separation product 124 and the oil-lean
mixture 120. The
separation can be effected by any one, or any combination, of gravity
separation, filters
(coalescing, granular media, cartridge, membrane, screen, pre-coat or types
otherwise capable of
filtering oil droplets), gas flotation units, hydrocyclones, centrifuges, and
devices to improve
coalescing such as plate packs.
[0059] The oil-lean mixture 120 is supplied to a scale forming solids
separator 160 for
effecting separation, from the oil-lean mixture 120, of a scale forming-lean
liquid 170 and a scale
forming-rich material 165. The scale forming-rich material can be, for
example, dissolved
solids, suspended solids, or free oil. This separation can be effected, for
example, by
evaporation, pressurized hot lime softening in combination with ion exchange,
or ceramic
membrane filtration in combination with ion exchange. In this respect, in some
embodiments,
the scale forming solids separator 160 may include an evaporator, a
pressurized hot lime
softening unit operation, or a ceramic membrane filtration unit operation.
Scale forming solids
that are concentrated within the scale forming-rich material, by virtue of the
separation, include
calcium-comprising compounds, magnesium-comprising compounds, and silica. In
some
embodiments, for example, the scale forming-lean liquid 170 is disposed at a
temperature that is
greater than 100 degrees Celsius. Removal of scale-forming materials, prior to
supplying of the
liquid 170 to the steam generator 200, is desirable so as to mitigate scaling
with the steam
generator 200.
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[0060] In some
embodiments, for example, prior to the supplying of the oil-lean mixture 120
to the scale forming solids separator 160, the oil-lean mixture 120 is admixed
with chemical
agents 125 for supporting or enabling processes effected within the separator
160, or for
mitigating against undesirable process conditions within the separator 160.
In some
embodiments, for example, where the separator 160 is an evaporator, the
chemical agents 125
can be a pH attenuating agent for mitigating against scale formation. The
chemical agents 125
are typically introduced downstream of the separation of the oil-lean mixture
120 from the
reservoir fluid-comprising mixture 110 so as not to unnecessarily consume the
chemical agents
125 prior to introduction to the separator 160.
[0061] In some
embodiments, for example, prior to the supplying of the oil-lean mixture 120
to the scale forming solids separator 160, the oil-lean mixture 120 is admixed
with make-up
water 122. The make-up water 122 may be added to compensate for reservoir
losses of steam,
and losses within the processing system, such as losses within purge streams.
The make-up
water 122 is typically introduced downstream of the separation of the oil-lean
mixture 120 from
the reservoir fluid-comprising mixture 110 so as not to use up capacity within
the oil separator
138.
[0062] The scale
forming-lean liquid 170 is conducted to a steam generator 190 for
conversion to pressurized steam 200 for use in recovering oil from the
hydrocarbon containing
reservoir 30. In this respect, the pressurized steam is conducted to the
hydrocarbon containing
reservoir 30 to effect mobilization of bitumen within the oil sands reservoir
30.
[0063] In one
aspect, the separating of an oil-lean mixture 120 from the reservoir fluid-
comprising mixture 110 is such that the concentration of oil within the oil-
lean mixture is greater
than 10 ppm. In some embodiments, for example, the concentration of oil within
the oil-lean
mixture is between 10 ppm and 250 ppm. In some embodiments, for example, the
concentration
of oil within the oil-lean mixture is between 10 ppm and 100 ppm. In some
embodiments, for
example, the concentration of oil within the oil-lean mixture is between 10
ppm and 30 ppm.
Separation processes, for effecting the separation, from the oil-lean mixture
120, of the scale
forming-lean liquid 170, in the form of evaporation, or ceramic membrane
filtration in
combination with ion exchange, are, typically, better able to process an oil-
lean mixture 120
having relatively higher oil contents, than other separation processes. As a
result, less costly de-
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oiling equipment is required to effect the production of the oil-lean mixture
120, having a
relatively higher oil content, when such separation processes are employed.
[0064] In another aspect, prior to being conducted to the steam generator
190, the scale
forming-lean liquid 170 can be supplied to a tank 230. In some embodiments,
for example, the
tank 230 has a volume equivalent to that of providing for a residence time,
for scale forming-lean
liquid 170 being received from the separator 160, of at least about 15
minutes. In some
embodiments, the tank 230 functions as a buffer for receiving surges in
production of the scale
forming-lean liquid 170, and for allowing steam generation to continue during
upsets within
upstream equipment (such as for example, when operation of the separator 160
becomes
suspended) or allowing production of scale forming-lean liquid 170 to continue
during upsets
within downstream equipment (such as, for example, when the steam generator
190 shuts down).
[0065] The wellhead 25 is fluidly coupled the steam generator 190 via a
fluid passage within
a fluid conductor 300 for supplying water contained within the reservoir fluid-
comprising
mixture to the steam generator 190. In some embodiments, the conditioning of
the reservoir
fluid-comprising mixture 110 (if any), the separating of the oil-lean mixture
120 from the
reservoir fluid-comprising mixture 110 (conditioned or unconditioned), the
supplying of the oil-
lean mixture 120 to the separator 160, and the separating of the scale forming-
lean liquid 170
from the oil-lean mixture 120 is effected within the fluid passage. In other
embodiments, for
example, the fluid passage extends from the heat exchanger 210 to the steam
generator 190, such
that the separating of the oil-lean mixture 120 from the reservoir fluid-
comprising mixture 110,
the supplying of the oil-lean mixture 120 to the separator 160, the separating
of the scale
forming-lean liquid 170 from the oil-lean mixture 120, the cooling of the
reservoir fluid-
comprising mixture 110 by the scale forming-lean liquid 170, and the supplying
of the scale
forming-lean liquid 170 to the steam generator 190 is effected within the
fluid passage.
100661 In another aspect, the entirety of the fluid passage of the fluid
conductor 300 is
disposed at a pressure that is greater than atmospheric pressure. In some
implementations,
additional compression machinery, downstream of the wellhead 25, for
pressurizing the
conducted fluid (in these instances, for example, such pressurization is
effected by subsurface
pumps), is not provided (in other embodiments, compression machinery may be
provided
immediately downstream of the wellhead 25 for assisting with production from
the well) yet the
13
CA 02956736 2017-02-01
oil-lean mixture 120 is supplied to the separator 160 at a pressure that is
greater than atmospheric
pressure. In this respect, the pressure within the fluid passage of the fluid
conductor 300
becomes progressively less up to at least the separator 160, but is still
maintained above the
pressure within the separator 160. In some implementations, each one of: (i)
the conditioning
(such as heating or cooling) of the reservoir fluid-comprising mixture, (ii)
the separating of an
oil-lean mixture from the cooled reservoir fluid-comprising mixture, (iii) the
supplying of the oil-
lean mixture to the separator 160, (iv) the separating of the scale forming-
lean liquid 170 from
the oil-lean mixture 120, (v) the cooling of the reservoir fluid-comprising
mixture 110 by the
scale forming-lean liquid 170, and (vi) the supplying of the scale forming-
lean liquid 170 to the
steam generator 190 is effected at a pressure that is greater than atmospheric
pressure. In some
of these implementations, for example, this pressure is at least 20 kPa above
atmospheric
pressure. In some of these implementations, for example, pressure along a
section of fluid
passage, from downstream of the wellhead to the evaporator, is progressively
reduced.
[0067] By avoiding having to, e.g., as an intermediate step between the
wellhead and the
separator 160, reduce fluid pressure within the fluid passage, such as, to
atmospheric pressure,
and then elevate the fluid pressure to above atmospheric pressure (e.g., when
an intermediate
unit operation is provided and operated at atmospheric pressure, such as an
atmospheric storage
tank), it may be possible to avoid capital cost associated with additional
compression machinery
that may be required to effect the supply of the scale-forming lean liquid 170
to the steam
generator 190 at a sufficiently high pressure. Such compression machinery may
include
compression machinery disposed upstream of the separator 160 for supplying the
oil-lean
mixture to the separator 160 at a pressure that is greater than atmospheric
pressure.
[0068] When the separator 160 includes an evaporator, by supplying the oil-
lean mixture 120
to the evaporator at a pressure that is greater than atmospheric pressure, the
evaporator may be
operated more efficiently or may occupy a smaller footprint.
[0069] When the separator 160 includes an evaporator, the evaporator
effects evaporation of
a portion of the oil-lean mixture to produce the scale forming-lean liquid 170
in the form of an
aqueous liquid distillate. The residue remaining after the evaporation of a
portion of the oil-lean
mixture includes dissolved solids. Periodically, this residue is purged from
the evaporator 160 as
the scale forming-rich material 165 for disposal.
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[0070] In some embodiments, the reservoir fluid-comprising mixture 110 is
indirectly cooled
by the scale forming-lean liquid 170. In this respect, the scale forming-lean
liquid is supplied to
the heat exchanger 210. Such supplying effects indirect heat transfer
communication between
the supplied scale forming-lean liquid 170 and the reservoir fluid-comprising
mixture 110 within
the heat exchanger 210. As a result, heat is transferred, within the heat
exchanger 210, from the
hotter reservoir fluid-comprising mixture 110 to the cooler scale forming-lean
liquid 170,
thereby effecting cooling of the reservoir fluid-comprising mixture 110,
without requiring an
external heat sink.
[0071] In another aspect, where the separator 160 includes an evaporator,
an upstream fluid
passage portion of the fluid conductor 300 is provided, and the upstream fluid
passage portion
extends upstream from the evaporator 160, and the entirety of the upstream
fluid passage portion
is disposed at a temperature that is at least (i.e .greater than or equal to)
the boiling point
temperature of the oil-lean mixture 120 at the pressure within the evaporator
160. In some
implementations, for example, this temperature is at least the boiling point
temperature of water
at 20 kPa above atmospheric pressure. In some implementations, each one of:
(i) the
conditioning (such as heating or cooling) of the reservoir fluid-comprising
mixture, (ii) the
separating of an oil-lean mixture from the cooled reservoir fluid-comprising
mixture, and (iii) the
supplying of the oil-lean mixture to the separator 160 is effected at a
temperature that is at least
(i.e. greater than or equal to) the boiling point temperature of the oil-lean
mixture 120 at the
pressure within the evaporator 160, such as at least the boiling point
temperature of water at 20
kPa above atmospheric pressure. In some implementations, the temperature along
the section of
fluid passage 300, from downstream of the wellhead to the evaporator, is
progressively reduced
to the boiling point temperature of the oil-lean mixture 120 at the pressure
within the evaporator
160.
[0072] By avoiding having to, e.g., as an intermediate step between the
wellhead and the
separator 160, reduce temperature within the fluid passage below that of the
boiling point
temperature of the oil-lean mixture 120 at the pressure within the evaporator
160, and then to
elevate the temperature to, or above, the boiling point temperature of the oil-
lean mixture 120 at
the pressure within the evaporator, it may be possible to avoid costs
associated with additional
heating of the scale-forming lean liquid 170 prior to supply to, or within,
the evaporator.
CA 02956736 2017-02-01
10073] In a related aspect, the scale forming-lean liquid 170 is the
aqueous liquid distillate,
such that the aqueous liquid distillate 170 is supplied to the heat exchanger
210 to function as the
cooling fluid. The reservoir fluid-comprising mixture 110 is cooled by the
aqueous liquid
distillate 170 to a temperature that is sufficient to enable the desired
separation of the oil-lean
mixture 120 from the reservoir fluid-comprising mixture 110 within the oil
separator 138 but is
maintained at a temperature that is greater than, or equal to, the boiling
point temperature of the
oil-lean mixture 120 at the pressure within the evaporator 160 (for example,
greater than, or
equal to, the boiling point temperature of water at 20 kPa above atmospheric
pressure). In some
implementations, the cooling of the reservoir fluid-comprising mixture 110 is
to a temperature
that is sufficiently high such that, even with heat losses, after the
separation of the oil-lean
mixture from the cooled reservoir fluid-comprising mixture 110, the
temperature of the oil-lean
mixture 120 being supplied to the evaporator 160 is greater than, or equal to,
the boiling point
temperature of the oil-lean mixture at the pressure within the evaporator 160.
In some
implementations, the temperature of the oil-lean mixture, supplied to the
evaporator 160, is
greater than, or equal to, the boiling point temperature of water at 20 kPa
above atmospheric
pressure. Again, this may potentially eliminate the requirement for either a
heat exchange step
between the hotter distillate 170 and the incoming feed of the oil-lean
mixture 120 to the
evaporator 160, or the input of additional heat within the evaporator
processes.
[0074] In those embodiments where cooling of the reservoir fluid-comprising
mixture 110 is
being effected by the aqueous liquid distillate 170, in some of these
embodiments, the cooling is
such that a desired separation of the oil-lean mixture 120 from the reservoir
fluid-comprising
mixture 110 is facilitated, while still enabling the supply of the oil-lean
mixture 120 to the
evaporator at a temperature that is greater than, or equal to, the boiling
point temperature of the
oil-lean mixture at the pressure within the evaporator 160. In other
embodiments, there is
additional quenching effect provided by added diluent, make-up water, and
other cooler process
streams, and such additional quenching effect complements the heat exchange
between the
aqueous liquid distillate 170 and the reservoir fluid-comprising mixture 110
such that an
additional external heat sink is not required for facilitating a desired
separation of the oil-lean
mixture 120 from the reservoir fluid-comprising mixture 110 while still
enabling the supply of
the oil-lean mixture 120 to the evaporator at a temperature that is greater
than, or equal to, the
boiling point temperature of the oil-lean mixture at the pressure within the
evaporator 160. In
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CA 02956736 2017-02-01
some cases, an additional external heat sink may be provided if such
operational flexibility is
desired and additional cooling, prior to supplying of the oil-lean mixture 120
to the evaporator
160, is required. Alternatively, the operating temperature of the evaporator
160 could be reduced
(such as by reducing the pressure of the oil-lean mixture 120 being supplied
to the evaporator) so
as to avoid incorporation of an additional external heat sink.
[0075] Reference throughout the specification to "one
embodiment/implementation," "an
embodiment/implementation," "some embodiments/implementations," "one aspect,"
"an aspect,"
or "some aspects" means that a particular feature, structure, method, or
characteristic described
in connection with the embodiment/implementation or aspect is included in at
least one
embodiment/implementation of the present invention. In this respect, the
appearance of the
phrases "in one embodiment/implementation" or "in an
embodiment/implementation" or "in
some embodiments/implementations" in various places throughout the
specification are not
necessarily all referring to the same embodiment/implementation. Furthermore,
the particular
features, structures, methods, or characteristics may be combined in any
suitable manner in one
or more embodiments/implementations.
[0076] Each numerical value should be read once as modified by the term
"about" (unless
already expressly so modified), and then read again as not so modified unless
otherwise
indicated in context. Also, in the summary and this detailed description, it
should be understood
that a concentration range listed or described as being useful, suitable, or
the like, is intended that
any and every concentration within the range, including the end points, is to
be considered as
having been stated. For example, "a range of from 1 to 10" is to be read as
indicating each and
every possible number along the continuum between about 1 and about 10. Thus,
even if specific
data points within the range, or even no data points within the range, are
explicitly identified or
refer to only a few specific data points, it is to be understood that
inventors appreciate and
understand that any and all data points within the range are to be considered
to have been
specified, and that inventors have disclosed and enabled the entire range and
all points within the
range.
[0077] In the above description, for purposes of explanation, numerous
details are set forth in
order to provide a thorough understanding of the present disclosure. However,
it will be
apparent to one skilled in the art that these specific details are not
required in order to practice
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CA 2956736 2017-04-10
the present disclosure. Although certain dimensions and materials are
described for
implementing the disclosed example embodiments, other suitable dimensions
and/or materials
may be used within the scope of this disclosure. All such modifications and
variations, including
all suitable current and future changes in technology, are believed to be
within the sphere and
scope of the present disclosure.
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