Note: Descriptions are shown in the official language in which they were submitted.
CA 02777956 2015-11-06
PROCESS FOR ENHANCED PRODUCTION OF HEAVY OIL USING
MICROWAVES
FIELD OF THE INVENTION
[0003] The present invention relates generally to a process for recovering
heavy
oil from a reservoir.
BACKGROUND OF THE INVENTION
[0004] Heavy oil is naturally formed oil with very high viscosity but often
contains impurities such as sulfur. While conventional light oil has
viscosities
ranging from about 0.5 centipoise (cP) to about 100 cP, heavy oil has a
viscosity that
ranges from 100 cP to over 1,000,000 cP. Heavy oil reserves are estimated to
equal
about fifteen percent of the total remaining oil resources in the world. In
the United
States alone, heavy oil resources are estimated at about 30.5 billion barrels
and heavy
oil production accounts for a substantial portion of domestic oil production.
For
example, in California alone, heavy oil production accounts for over sixty
percent of
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the states total oil production. With reserves of conventional light oil
becoming more
difficult to find, improved methods of heavy oil extractions have become more
important. Unfortunately, heavy oil is typically expensive to extract and
recovery is
much slower and less complete than for lighter oil reserves. Therefore, there
is a
compelling need to develop a more efficient and effective means for extracting
heavy
oil.
[0005] Viscous oil that is too deep to be mined from the surface may be
heated with hot fluids or steam to reduce the viscosity sufficiently for
recovery by
production wells. One thermal method, known as steam assisted gravity drainage
(SAGD), provides for steam injection and oil production to be carried out
through
separate wellbores. The optimal configuration is an injector well which is
substantially parallel to and situated above a producer well, which lies
horizontally
near the bottom of the formation. Thermal communication between the two wells
is
established and, as oil is mobilized and produced, a steam chamber or chest
develops.
Oil at the surface of the enlarging chest is constantly mobilized by contact
with steam
and drains under the influence of gravity.
[0006] There are several patents on the improvements to SAGD operation.
U.S. Patent No. 6, 814,141 describes applying vibrational energy in a well
fracture to
improve SAGD operation. U.S. Patent No. 5,899,274 teaches addition of solvents
to
improve oil recovery. U.S. Patent No. 6,544,411 describes decreasing the
viscosity of
crude oil using ultrasonic source. U.S. Patent No. 7,091,460 claims in situ,
dielectric
heating using variable radio frequency waves.
[0007] In a recent patent publication (U.S. Patent Publication
20070289736/US-Al, filed May 25, 2007), it is disclosed to extract
hydrocarbons
from a target formation, such as a petroleum reservoir, heavy oil, and tar
sands by
utilizing microwave energy to fracture the containment rock and for
liquification or
vitalization of the hydrocarbons.
[0008] In another recent patent publication (US Patent Publication
20070131591/US-Al, filed December 14, 2006), it is disclosed that lighter
hydrocarbons can be produced from heavier carbon-base materials by subjecting
the
heavier materials to microwave radiations in the range of about 4 GHz to about
18
GHz. This publication also discloses extracting hydrocarbons from a reservoir
where
a probe capable of generating microwaves is inserted into the oil wells and
the
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microwaves are used to crack the hydrocarbons with the cracked hydrocarbon
thus
produced being recovered at the surface.
100091 Despite
these disclosures, it is unlikely that direct microwave cracking
or heating of hydrocarbons would be practical or efficient. It is known that
microwave energy is absorbed by a polar molecule with a dipole moment and
bypasses the molecules that lack dipole moment. The absorption of the
microwave
energy by the polar molecule causes excitation of the polar molecule thereby
transforming the microwave energy into heat energy (known as the coupling
effect).
Accordingly, when a molecule with a dipole moment is exposed to microwave
energy
it gets selectively heated in the presence of non-polar molecules. Generally,
heavy
oils comprise non-polar hydrocarbon molecules; accordingly, hydrocarbons would
not
get excited in the presence of microwaves.
[0010]
Additionally, while the patent publication above claims to break the
hydrocarbon molecules, the energy of microwave photons is very low relative to
the
energy required to cleave a hydrocarbon molecule. Thus, when hydrocarbons are
exposed to microwave energy, it will not affect the structure of a hydrocarbon
molecule. (See, for example, "Microwave Synthesis", CEM Publication, 2002 by
Brittany Hayes).
[0011] There
have been a number of prior proposals set forth for the upgrading of
useful fuels from oil shales and tar sands in situ but, for various reasons,
none has
gained commercial acceptance. One category of such techniques utilizes partial
combustion of the hydrocarbonaceous deposits, but these techniques have
generally
suffered one or more of the following disadvantages: lack of precise control
of the
combustion, environmental pollution resulting from disposing of combustion
products, and general inefficiency resulting from undesired combustion of the
resource.
100121 Another
category of proposed in situ upgrading techniques would utilize
electrical energy for the heating of the formations. For example, in the U.S.
Pat. No.
2,634,961 there is described a technique wherein electrical heating elements
are
imbedded in pipes and the pipes are then inserted in an array of boreholes in
oil shale.
The pipes are heated to a relatively high temperature and eventually the heat
conducts
through the oil shale to achieve a pyrolysis thereof. Since oil shale is not a
good
conductor of heat, this technique is problematic in that the pipes must be
heated to a
considerably higher temperature than the temperature required for pyrolysis in
order
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to avoid inordinately long processing times. However, overheating of some of
the oil
shale is inefficient in that it wastes input electrical energy, and may
undesirably
carbonize organic matter and decompose the rock matrix, thereby limiting the
yield.
Further electrical in situ techniques have been termed as "ohmic ground
heating" or
"electrothermic" processes wherein the electric conductivity of the formations
is
relied upon to carry an electric current as between electrodes placed in
separated
boreholes. An example of this type of technique, as applied to tar sands, is
described
in U.S. Pat. No. 3,848,671. A problem with this technique is that the
formations under
consideration are generally not sufficiently conductive to facilitate the
establishment
of efficient uniform heating currents. Variations of the electrothermic
techniques are
known as "electrolinking", "electrocarbonization", and "electrogasification"
(see, for
example, U.S. Pat. No. 2,795,279). In electrolinking or electrocarbonization,
electric
heating is again achieved via the inherent conductivity of the fuel bed. The
electric
current is applied such that a thin narrow fracture path is formed between the
electrodes. Along this fracture path, pyrolyzed carbon forms a more highly
conducting link between the boreholes in which the electrodes are implanted.
Current
is then passed through this link to cause electrical heating of the
surrounding
formations. In the electrogasification process, electrical heating through the
formations is performed simultaneously with a blast of air or steam.
Generally, the
just described techniques are limited in that only relatively narrow filament-
like
heating paths are formed between the electrodes. Since the formations are
usually not
particularly good conductors of heat, only non-uniform heating is generally
achieved.
The process tends to be slow and requires temperatures near the heating link
which
are substantially higher than the desired pyrolyzing temperatures, with the
attendant
inefficiencies previously described.
[0013] Another
approach to in situ upgrading has been termed "electrofracturing".
In one variation of this technique, described in U.S. Pat. No. 3,103,975,
conduction
through electrodes implanted in the formations is again utilized, the heating
being
intended, for example, to increase the size of fractures in a mineral bed. In
another
version, disclosed in U.S. Pat. No. 3,696,866, electricity is used to fracture
a shale
formation and a thin viscous molten fluid core is formed in the fracture. This
core is
then forced to flow out to the shale by injecting high pressured gas in one of
the well
bores in which an electrode is implanted, thereby establishing an open
retorting
channel.
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[0014] In general, the above described techniques are limited by the
relatively low
thermal and electrical conductivity of the bulk formations of interest. While
individual
conductive paths through the formations can be established, heat does not
radiate at
useful rates from these paths, and efficient heating of the overall bulk is
difficult to
achieve.
BRIEF SUMMARY OF THE DISCLOSURE
[0015] A process wherein 1120 is injected into a subterranean region
through a
first wellbore of a steam assisted gravity drainage operation. Microwaves are
introduced into the region at a frequency sufficient to excite the H20
molecules and
increase the temperature of at least a portion of the 1120 within the region
to produce
heated 1120 while heating an absorbent material to generate a heated absorbent
material. At least a portion of the heavy oil in the region is heated by
contact with the
heated H20 to produce heated heavy oil. Heated heavy oil is produced through a
second wellbore of the steam assisted gravity drainage operation while
upgrading the
heated heavy oil in-situ with the heated absorbent material in the second
wellbore.
Upgraded heavy oil is thereby recovered with the steam assisted gravity
drainage
operation from the subterranean region. In this embodiment a portion of the
1120 is=
injected as steam and the steam contacts with at least a portion of the heavy
oil in the
region so as to heat the portion of the heavy oil and reduce its viscosity so
that it flows
generally towards the second wellbore.
[0016] In another process liquid H20 is injected into the region through a
first
wellbore of a steam assisted gravity drainage operation. Microwaves are
introduced
into the subterranean region at a frequency sufficient to excite the liquid
H20
molecules and increase the temperature of at least a portion of the liquid H2O
within
the region to produce heated gaseous 1120 while heating an absorbent material
to
generate a heated absorbent material. At least a portion of the heavy oil in
the region
is heated by contact with the heated gaseous H20 to produce heated heavy oil.
Heated
heavy oil is then produced through a second wellbore of the steam assisted
gravity
drainage operation while upgrading the heated heavy oil in-situ with the
heated
absorbent material in the second wellbore. Upgraded heavy oil is thereby
recovered
with the steam assisted gravity drainage operation from the subterranean
region. In
this embodiment a portion of the liquid H20 is injected as steam and the steam
CA 02777956 2015-11-06
contacts with at least a portion of the heavy oil in the region so as to heat
the portion
of the heavy oil and reduce its viscosity so that it flows generally towards
the second
wellbore.
[00171 In yet another
embodiment a process injects H20 into a subterranean
region through an injection wellbore of a steam assisted gravity drainage
operation.
Microwaves are introduced into the region at a frequency sufficient to excite
the H20
molecules and increase the temperature of at least a portion of the H20 within
the
region to produce heated H20 while heating an absorbent material to generate a
heated absorbent material. At least a portion of the bitumen is heated to
below
3000cp in the region by contact with the heated H20 to produce a heated heavy
oil
and an imposed pressure differential between the injection wellbore and a
production
wellbore. Heated heavy oil is then produced through the production wellbore of
the
steam assisted gravity drainage operation while upgrading the heated heavy oil
in-situ
with the heated absorbent material in the second wellbore. Upgraded heavy oil
is
thereby recovered with the steam assisted gravity drainage operation from the
subterranean region. In this embodiment a portion of the H20 is injected as
steam and
the steam contacts with at least a portion of the heavy oil in the region so
as to heat
the portion of the heavy oil and reduce its viscosity so that it flows
generally towards
the second wellbore. Additionally, the injection wellbore and the production
wellbore
are from 3 meters to 7 meters apart and the injection wellbore is located
higher than
the production wellbore.
[0017a] In a further embodiment of the present invention there is provided a
process comprising: (a) injecting H20 into a subterranean region through an
injection
wellbore of a steam assisted gravity drainage operation; (b) introducing
microwaves
into the region at a frequency sufficient to excite the H20 molecules and
increase the
temperature of at least a portion of the H20 within the region to produce
heated H20
while heating an absorbent material to generate a heated absorbent material;
(c)
heating at least a portion of a hydrocarbon to below 3000 cp in the region by
contact
with the heated H20 to produce a heated heavy oil and an imposed pressure
differential between the injection wellbore and a production wellbore; and (d)
producing the heated heavy oil through the production wellbore of the steam
assisted
gravity drainage operation while upgrading the heated heavy oil in-situ with
the
heated absorbent material in the second wellbore; thereby recovering upgraded
heavy
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Oil with the steam assisted gravity drainage operation from the subterranean
region;
wherein the injection wellbore and the production wellbore are from 3 meters
to 7
meters apart and the injection wellbore is located higher than the production
wellbore;
wherein the H20 is injected as steam and the steam contacts with at least a
portion of
the heavy oil in the region so as to heat the portion of the heavy oil and
reduce its
viscosity so that it flows generally towards the second wellbore.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] A more complete understanding of the present invention and benefits
thereof may be acquired by referring to the following description taken in
conjunction
with the accompanying drawings in which:
[0019] Figure 1 is a schematic diagram illustrating a heavy oil heating
process,
wherein wave guides are used to introduce the microwaves to the reservoir.
[0020] Figure 2 is a schematic diagram illustrating a heavy oil heating
process
wherein the microwaves are introduced into the reservoir using a microwave
generator located within the reservoir.
[0021] Figure 3 depicts one embodiment of the process.
[0022] Figure 4 depicts another embodiment of the process.
[0023] Figure 5 depicts yet another embodiment of the process.
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,
DETAILED DESCRIPTION
[0024]
Turning now to the detailed description of the preferred arrangement or
arrangements of the present invention, it should be understood that the
inventive
features and concepts may be manifested in other arrangements and that the
scope of
the invention is not limited to the embodiments described or illustrated. The
scope of
the invention is intended only to be limited by the scope of the claims that
follow.
[0025]
In this description, the term water is used to refer to H2O in a liquid
state
and the term steam is used to refer to H20 in a gaseous state.
[0026]
The present embodiment discloses a process of producing upgraded
heavy oil from a wellbore. To produce the upgraded heavy oil a heated
absorbent
material is used to upgrade the heavy oil. The heated absorbent material is
heated by
the microwaves in the steam assisted gravity drainage operation.
[0027]
Turning now to Figure 1, wellbores 14, 15 and 16 are illustrated. Wellbore
14 extends from the surface 10 into a lower portion of subterranean region 12.
Wellbore 16 extends from the surface 10 into subterranean region 12 and
generally
will be higher than wellbore 14. Wellbore 16 will be used to inject H2O and it
is
preferred that it is located higher than wellbore 14 so that when the injected
H20 heats
the heavy oil, the heavy oil will flow generally towards wellbore 14, which is
used to
extract the heavy oil from the reservoir. In one embodiment a portion of the
H20 is
injected as steam and the steam contacts with at least a portion of the heavy
oil in the
region so as to heat the portion of the heavy oil and reduce its viscosity so
that it flows
generally towards the second wellbore. Wellbore 15 is used to introduce
microwaves
to the reservoir and it is preferred that wellbore 15 be located intermittent
to wellbores
14 and 15; although, other arrangements are possible.
[0028]
The process can be used as an enhanced oil recovery technique in any
situation where hydrocarbons are produced from the subsurface with a
production
well. Examples where the present process can be used include cyclic steam
stimulation (CSS), steam assisted gravity drainage (SAGD), vapor extraction
process
(VAPEX), toe to heel air injection (THAI) or combustion overhead gravity
drainage
(COGD). In all these processes there exists a need to upgrade the bitumen in-
situ.
[0029]
In operation, steam generated in boiler 11 is provided into the reservoir
12 through upper wellbore leg 16. The steam heats the heavy oil within zone 17
of
the oil-bearing portion 13 of reservoir 12 causing it to become less viscous
and,
hence, increase its mobility. The heated heavy oil flows downward by gravity
and is
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produced through wellbore leg 14. While Figure 1 illustrates a single wellbore
for
injection and a single wellbore for extraction, other configurations are
within the
scope of the invention, for example, there can be two or more separate
wellbores to
provide steam injection and two or more separate wellbores for production.
Similarly,
multiple wellbores can be used for microwave introduction to the reservoir, as
further
discussed below.
[0030]
Generally, the wellbore for steam injection, wellbore 16, will be
substantially parallel to and situated above the wellbore for production,
wellbore 14,
which is located horizontally near the bottom of the formation. Pairs of steam
injection wellbores and production wellbores will generally be close together
and
located at a suitable distance to create an effective steam chamber and yet
minimizing
the preheating time. Typically, the pairs of injection and production
wellbores will be
from about 3 meters to 7 meters apart and preferably there will be about 5
meters of
vertical separation between the injector and producer wellbores. In other
embodiments it is possible for the injection and production wellbores be
anywhere
from 1, 3, 5, 7, 12, 15, 20 even 25 meters of horizontal separation apart.
Additionally,
in other embodiments it is possible for the injection and production wellbores
be
anywhere from 1, 3, 5, 7, 12, 15, 20 even 25 meters of vertical separation
apart. In
this type of SAGD operation, the zone 17 is preheated by steam circulation
until the
reservoir temperature between the injector and producer wellbore is at a
temperature
sufficient to drop the viscosity of the heavy oil so that it has sufficient
mobility to
flow to and be extracted through wellbore 14. Generally, the heavy oil will
need to be
heated sufficiently to reduce its viscosity to below 3000 cP; however, lower
viscosities are better for oil extraction and, thus, it is preferable that the
viscosity be
below 1500 cP and more preferably below 1000 cP. Preheating zone 17 involves
circulating steam inside a liner using a tubing string to the toe of the
wellbore. Both
the injector and producer would be so equipped. Steam circulation through
wellbores
14 and 16 will occur over a period of time, typically about 3 months. During
the
steam circulation, heat is conducted through the liner wall into the reservoir
near the
liner. At some point before the circulation period ends, the temperature
midway
between the injector and producer will reach a temperature wherein the bitumen
will
become movable typically around 3000 cP or less or from about 80 to 100 C.
Once
this occurs, the steam circulation rate for wellbore 14 will be gradually
reduced while
the steam rate for the injector wellbore 16 will be maintained or increased.
This
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imposes a pressure gradient from high, for the area around wellbore 16, to
low, for the
area around wellbore 14. With the oil viscosity low enough to move and the
imposed
pressure differential between the injection and production wellbores, steam
(usually
condensed to hot water) starts to flow from the injector into the producer. As
the
steam rate is continued to be adjusted downward in wellbore 14 and upward in
wellbore 16, the system arrives at steam assisted gravity drainage operation
with no
steam injection through wellbore 14 and all the steam injection through
wellbore 16.
Once hydraulic communication is established between the pair of injector and
producer wellbores, steam injection in the upper well and liquid production
from the
lower well can proceed. Due to gravity effects, the steam vapor tends to rise
and
develop a steam chamber at the top section 19 of zone 17. The process is
operated so
that the liquid/vapor interface is maintained between the injector and
producer
wellbores to form a steam trap which prevents live steam from being produced
through the lower wellbore.
[0031] During operation, steam will come into contact with the heavy oil
in
zone 17 and, thus, heat the heavy oil and increase its mobility by lessening
its
viscosity. Heated heavy oil will tend to flow downward by gravity and collect
around
wellbore 14. Heated heavy oil is produced through wellbore 14 as it collects.
Steam
contacting the heavy oil will lose heat and tend to condense into water. The
water
will also tend to flow downward toward wellbore 14. In past SAGD operations,
this
water would also be produced through wellbore 14. Such produced water would
need
to be treated to reduce impurities before being reheated in the boiler for
subsequent
injection. As the process continues operation, zone 17 will expand with heavy
oil
production occurring from a larger portion of oil-bearing portion 13 of
subterranean
formation 12.
[0032] Turning again to Figure 1, the current invention provides for
microwave generator 18 to generate microwaves which are directed underground
and
into zone 17 of the reservoir through a series of wave guides 20. The diameter
of the
wave guides will preferably be more than 3 inches in order to ensure good
transmission of the microwaves. Within the reservoir, the microwaves will be
at a
frequency substantially equivalent to the resonant frequency of the water
within the
reservoir so that the microwaves excite the water molecules causing them to
heat up
and/or substantially equivalent to the resonant frequency of the absorbent
material so
that the absorbent material will be heated. Optimally, the microwaves will be
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introduced at or near the liquid vapor interface so that condensed steam is
reheated
from its water state back into steam further supplying the steam chamber. In
some
embodiments the microwave frequency will be not greater than 3000 megahertz
and/or at a resonant frequency of water. Based on the resonant frequency of
water,
the optimum frequency will be 2450 megahertz; however, power requirements and
other factors may dictate that another frequency is more economical.
Additionally,
salt and other impurities may enhance the coupling effect (production of heat
by
resonance of a polar or conductive molecule with microwave energy); thus, the
presence of salt is desirable.
[0033] The
absorbent material can be made from any conventionally known
absorbent material capable of being heated with an RF emitter. Examples of
types of
absorbent materials include graphite, activated carbon, metal, metal oxides,
metal
sulfides or combinations of these materials.
[0034] The
emitter can be disposed in any location capable of emitting
frequencies to the absorbent material. Examples of locations the emitter can
be
placed include next to the absorbent material, above ground, below ground,
adjacent
to the absorbent material, or even to parallel the absorbent material.
Likewise the
antennas for the emitter can be placed anywhere as long as it is capable of
heating the
absorbent material. Examples of locations the antenna can be placed include
next to
the absorbent material, above ground, below ground, adjacent to the absorbent
material, or even parallel to the absorbent material.
[0035] In one
embodiment the heated absorbent material can achieve a
temperature ranging from 315 to 650 C or even 425 to 535 C. The temperature
range of the heated absorbent well will be adjusted so that maximum upgrading
of the
hydrocarbons can occur.
[0036] Turning
now to Fig. 2, a further embodiment of the invention is illustrated
wherein, instead of using wave guides, power is supplied through electrical
wire 22 to
microwave generating probe 24. The electrical power can be supplied to wire 22
by
any standard means such as generator 26.
[0037] In still
another embodiment of the invention, also illustrated in Fig. 2,
no steam boiler is used. Instead water is introduced directly into wellbore 16
through
pipe 28 and valve 30. Wellbore 16 then introduces water into the reservoir
instead of
steam and the entire steam production would be accomplished through use of the
microwave generators. This embodiment of the invention has the added advantage
of
CA 02777956 2012-05-22
avoiding costly water treatment that is necessary when using a boiler to
generate
steam because, as discussed above, salt and other impurities can aid in heat
generation. In a preferred embodiment, the water introduced into the reservoir
would
have a salt content greater than the natural salt content of the reservoir,
which is
typically about 5,000 to 7,000 ppm. Accordingly, it is preferred that the
introduced
water has a salt content greater than 10,000 ppm. For enhanced heat generation
30,000 to 50,000 ppm is more preferred.
[0038] Microwave
generators useful in the invention would be ones suitable
for generating microwaves in the desired frequency ranges recited above.
Microwave
generators and wave guide systems adaptable to the invention are sold by Cober
Muegge LLC, Richardson Electronics and CPI International Inc.
[0039] Steam to
oil ratio is an important factor in SAGD operations and
typically the amount of water required will be 2 to 3 times the oil
production. Higher
steam to oil production ratios require higher water and natural gas costs. The
present
invention reduces water and natural gas requirements and reduces some of the
water
handling involving recycling, cooling, and cleaning up the water.
[0040] Figure 3
depicts one embodiment of the process wherein a production
wellbore 102 is disposed within a reservoir 104 for heavy oil 106 recovery. In
this
embodiment the process is used in a CSS/SAGD operation, henceforth steam 108
is
shown to be injected downhole. Figure 3 depicts the absorbent material 110 is
used to
line the vertical well. This permits the hydrocarbons 116 produced to contact
the
heated absorbent material 110 and be upgraded. The antenna 112 is shown in
this
embodiment to be parallel against the absorbent material 110.
[0041] Figure 4
depicts another embodiment of the process wherein a production
wellbore 102 is disposed within a reservoir 104 for hydrocarbon 106 recovery.
In this
embodiment the process is used in a CSS/SAGD operation, henceforth steam 108
is
shown to be injected downhole. Figure 4 depicts the absorbent material 110 as
a rod
placed in the center of the production well. This permits the hydrocarbons 106
produced to contact the heated absorbent material 110 and be upgraded. One
distinctive feature of this embodiment is that the absorbent material 110 can
be easily
replaced, as one would simply extract the absorbent material rod from the
center of
the production well. The antenna 112 is shown in this embodiment to be along
the
outer wall of the production well 102.
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[0042] Figure 5 depicts another embodiment of the process wherein a
production
wellbore 102 is disposed within a reservoir 104 for hydrocarbon 106 recovery.
In this
embodiment the process is used in a CSS/SAGD operation, henceforth steam 108
is
shown to be injected downhole. Figure 5 depicts the absorbent material 110 as
pellets
dispersed throughout the heavy oil. In this process a membrane 114 can be
utilized to
restrict the flow of the absorbent material 110 into the processing of the
heavy oil 106.
This permits the heavy oil 106 produced to be contacted with the heated
absorbent
material 110 with a greater surface area and be upgraded. The antenna 112 is
shown
in this embodiment to be along the outer wall of the production well 102.
[0043] While figures 3-5 each depict differing ways of incorporating the
process
into a production wellbore it should be noted that it is possible to combine
two or all
of the processes to improve the in situ upgrading of the hydrocarbons. For
example, it
is possible to both utilize an absorbent material as a liner for the
production well and
as pellets dispersed throughout the hydrocarbons. Or a combination of all
three
permutations where the absorbent material is placed as a rod in the center of
the
production wellbore, dispersed throughout the heavy oil and used to line the
production well.
[0044] Although the systems and processes described herein have been
described
in detail, it should be understood that various changes, substitutions, and
alterations
can be made without departing from the scope of the invention as defined by
the
following claims. Those skilled in the art may be able to study the preferred
embodiments and identify other ways to practice the invention that are not
exactly as
described herein. The scope of the claims should not be limited by the
preferred
embodiments set forth in the description, but should be given the broadest
interpretation consistent with the description as a whole.
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