U.S. patent application number 16/936142 was filed with the patent office on 2020-11-05 for extraction methods and systems for recovery of oil from reservoirs containing mobile water.
The applicant listed for this patent is CEC North Star Energy Ltd.. Invention is credited to Jonathan Bryan, Donald E.H. Jones, Apostolos Kantzas, Robert Richardson.
Application Number | 20200347708 16/936142 |
Document ID | / |
Family ID | 1000004975033 |
Filed Date | 2020-11-05 |
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United States Patent
Application |
20200347708 |
Kind Code |
A1 |
Kantzas; Apostolos ; et
al. |
November 5, 2020 |
EXTRACTION METHODS AND SYSTEMS FOR RECOVERY OF OIL FROM RESERVOIRS
CONTAINING MOBILE WATER
Abstract
The present disclosure relates to, according to some
embodiments, an extraction process for recovering an oil from an
oil reservoir comprising a mobile water. The extraction process
includes the step of injecting a first solvent into the oil
reservoir through the at least one injection well to form a first
mixture, the first mixture comprising the first solvent, a first
portion of mobile water, and a first portion of oil. Additionally,
the extraction process includes the steps of recovering the first
mixture from the at least one production well to produce a first
recovered oil mixture, the first recovered oil mixture comprising
the first solvent, the first portion of the mobile water, and the
first portion of oil; separating the first recovered oil mixture to
produce a first recovered oil fraction that is separated from the
first portion of mobile water and the first solvent; and injecting
a second solvent into the oil reservoir through the at least one
injection well to form a second mixture, the second mixture
comprising the second solvent, a second portion of mobile water,
and a second portion of oil. The extraction process also includes
the steps of recovering the second mixture from the at least one
production well to produce a second recovered oil mixture, the
second recovered oil mixture comprising the second solvent, the
second portion of the mobile water, and the second portion of oil,
and separating the second recovered oil mixture to produce a second
recovered oil fraction that is separated from the second portion of
mobile water and the second solvent.
Inventors: |
Kantzas; Apostolos;
(Calgary, CA) ; Bryan; Jonathan; (Calgary, CA)
; Richardson; Robert; (Calgary, CA) ; Jones;
Donald E.H.; (Calgary, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CEC North Star Energy Ltd. |
Calgary |
|
CA |
|
|
Family ID: |
1000004975033 |
Appl. No.: |
16/936142 |
Filed: |
July 22, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16120965 |
Sep 4, 2018 |
10760389 |
|
|
16936142 |
|
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62599439 |
Dec 15, 2017 |
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62554716 |
Sep 6, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 43/166 20130101;
E21B 43/40 20130101; E21B 37/06 20130101; E21B 43/34 20130101; E21B
43/164 20130101 |
International
Class: |
E21B 43/16 20060101
E21B043/16; E21B 43/34 20060101 E21B043/34; E21B 43/40 20060101
E21B043/40 |
Claims
1. An extraction process for recovering oil from an oil reservoir
comprising mobile water, the extraction process comprising: (a)
establishing at least one injection well and at least one
production well; (b) injecting a first solvent into the oil
reservoir through the at least one injection well to form a first
mixture, the first mixture comprising the first solvent, a first
portion of mobile water, and a first portion of oil, wherein the
first solvent comprises a light hydrocarbon selected from the group
consisting of a methane, an ethane, a propane, a butane, a pentane,
a hexane, and combinations thereof; (c) recovering the first
mixture from the at least one production well to produce a first
recovered oil mixture, the first recovered oil mixture comprising
the first solvent, the first portion of the mobile water, and the
first portion of oil; (d) separating the first recovered oil
mixture to produce a first recovered oil fraction that is separated
from the first portion of mobile water and the first solvent; and
(e) injecting a second solvent into the oil reservoir through the
at least one injection well to form a second mixture, the second
mixture comprising the second solvent, a second portion of mobile
water, and a second portion of oil, wherein the second solvent
comprises a non-petroleum based solvent selected from the group
consisting of a terpene, a limonene, a hemiterpene, a monoterpene,
an alcohol, a sesquiterpene, a diterpene, a triterpene, a
tetraterpene, and combinations thereof.
2. The extraction process according to claim 1, further comprising
(f) recovering the second mixture from the at least one production
well to produce a second recovered oil mixture, the second
recovered oil mixture comprising the second solvent, the second
portion of the mobile water, and the second portion of oil
3. The extraction process according to claim 2, further comprising
(g) separating the second recovered oil mixture to produce a second
recovered oil fraction that is separated from the second portion of
mobile water and the second solvent.
4. The extraction process according to claim 1, wherein one or more
of the first solvent further comprises water and the second solvent
comprises water.
5. The extraction process according to claim 3, further comprising
combining the first recovered oil mixture and the second recovered
oil mixture to produce a combined recovered oil mixture, wherein
the combined recovered oil fraction comprises a yield of about 50%
to about 90% of the oil present in the oil reservoir prior to the
extraction process.
6. The extraction process according to claim 1, wherein one or more
of: the first solvent is at a temperature from about 10.degree. C.
to about 40.degree. C. during the step of injecting the first
solvent into the oil reservoir through the at least one injection
well, and the second solvent is at a temperature from about
10.degree. C. to about 40.degree. C. during the step of injecting
the second solvent into the oil reservoir through the at least one
injection well.
7. The extraction process according to claim 5, wherein the water
is present at a concentration from about 0.1% to about 50%, by
volume of the first solvent.
8. The extraction process according to claim 1, further comprising
injecting the separated first solvent into the oil reservoir
through the at least one injection well to form a combined
separated first solvent and oil mixture.
9. The extraction process according to claim 3, further comprising
injecting the separated second solvent into the oil reservoir
through the at least one injection well to form a combined
separated second solvent and oil mixture.
10. The extraction process according to claim 1, further comprising
injecting water into the oil reservoir through the at least one
injection well to form an injected water and oil mixture.
11. The extraction process according to claim 10, wherein the water
comprises a water exogenous to the oil reservoir.
12. The extraction process according to claim 10, wherein injecting
water into the oil reservoir through the at least one injection
well is performed after the injecting the second solvent into the
oil reservoir through the at least one injection well.
13. The extraction process according to claim 3, further
comprising: (h) adding a third solvent selected from the group
consisting of CO.sub.2, and N.sub.2, into the oil reservoir through
the at least one injection well; (i) shutting the oil reservoir for
a time of from about 1 day to about 7 days to form a combined third
solvent and second residual oil mixture; and (j) opening the oil
reservoir; and recovering at least a portion of the third solvent
and second residual oil mixture from the at least one production
well to produce a recovered third solvent and second residual oil
mixture.
14. The extraction process according to claim 3, wherein steps (a)
to (g) are repeated at least once.
15. The extraction process according to claim 1, wherein both the
first solvent and the second solvent are simultaneously injected
through the at least one injection well.
16. An extraction system for extracting and recovering an oil from
an oil reservoir comprising mobile water, the extraction system
comprising: (a) at least one injection well connected to the oil
reservoir through an injection stream; (b) at least one production
well connected to the oil reservoir through a recovery stream; (c)
a first solvent reservoir connected to the injection well through a
first solvent stream, wherein the injection well is configured to
receive a first solvent from the first solvent reservoir through
the first solvent stream, and wherein the first solvent comprises a
light hydrocarbon selected from the group consisting of a methane,
an ethane, a propane, a butane, a pentane, a hexane, and
combinations thereof; and (d) a second solvent reservoir connected
to the injection well through a second solvent stream, wherein the
injection well is configured to receive a second solvent from the
second solvent reservoir through the second solvent stream, and
wherein the second solvent comprises a non-petroleum based solvent
selected from the group consisting of a terpene, a limonene, a
hemiterpene, a monoterpene, an alcohol, a sesquiterpene, a
diterpene, a triterpene, a tetraterpene, and combinations
thereof.
17. The extraction system of claim 16, further comprising: (e) a
production treating facility connected to the production well
through an oil recovery stream, wherein the production treating
facility is configured to receive a first solvent and oil mixture
and a second solvent and oil mixture from the production well; and
(f) a recovered oil reservoir connected to the production well
through the oil recovery stream, wherein the recovered oil
reservoir is configured to receive a recovered oil from the
production treating facility through a recovered oil stream.
18. The extraction system of claim 17, wherein the first solvent
reservoir is connected to the production treating facility through
a first solvent recycle stream, and wherein the first solvent
reservoir is configured to receive a recycled first solvent from
the production treating facility through the first solvent recycle
stream.
19. The extraction system of claim 17, wherein the second solvent
reservoir is connected to the production treating facility through
a second solvent recycle stream, and wherein the second solvent
reservoir is configured to receive a recycled second solvent from
the production treating facility through the second solvent recycle
stream.
20. An extraction process for recovering oil from an oil reservoir
comprising mobile water, the extraction process comprising: (a)
establishing at least one injection well and at least one
production well; (b) injecting a first solvent into the oil
reservoir through the at least one injection well to form a first
mixture, the first mixture comprising the first solvent, a first
portion of mobile water, and a first portion of oil, wherein the
first solvent comprises a non-petroleum based solvent selected from
the group consisting of a terpene, a limonene, a hemiterpene, a
monoterpene, an alcohol, a sesquiterpene, a diterpene, a
triterpene, a tetraterpene, and combinations thereof; (c)
recovering the first mixture from the at least one production well
to produce a first recovered oil mixture, the first recovered oil
mixture comprising the first solvent, the first portion of the
mobile water, and the first portion of oil; (d) separating the
first recovered oil mixture to produce a first recovered oil
fraction that is separated from the first portion of mobile water
and the first solvent; and (e) injecting a second solvent into the
oil reservoir through the at least one injection well to form a
second mixture, the second mixture comprising the second solvent, a
second portion of mobile water, and a second portion of oil,
wherein the second solvent comprises a light hydrocarbon selected
from the group consisting of a methane, an ethane, a propane, a
butane, a pentane, a hexane, and combinations thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. Non-Provisional
Application No. 16/120,965, filed on Sep. 4, 2018, which claims
priority to U.S. Provisional Application No. 62/599,439, filed Dec.
15, 2017, and also claims priority to U.S. Provisional Application
No. 62/554,716, filed Sep. 6, 2017. The contents of all of the
above are hereby incorporated in their entirety by reference.
BACKGROUND
[0002] Oils refer to crude oils which have high specific gravity
and viscosity and are therefore difficult to extract commercially
because they do not readily flow. Typically, these oils will have
viscosities greater than 1000 mPa.s (centiPoise) or specific
gravities greater than 0.934 kg/m.sup.3 at 15.5.degree. C.
(60.degree. F.) (i.e. less than 20 API). Oil wet reservoirs are oil
deposits where the oil is the rock wetting fluid. Typically, these
reservoirs have poorer recoveries due to the oil's strong adherence
to the reservoir rock. There has long been sought a means to
accelerate oil production processes by permitting the oil to flow
more readily thereby increasing the rate of return on capital and
decreasing the financial risk of such oil production projects.
[0003] One approach to oil extraction involves the use of steam in
a thermal stimulation to facilitate oil extraction. Steam raises
the temperature of the oil and thereby reduces its viscosity and
allows it to flow more easily. The two main traditional approaches
used in steam recovery systems have been "huff and puff" (i.e.,
cyclic steaming) and steam floods. Steam stimulation is subject to
a number of problems, including heat losses during injection, clay
swelling problems, thief zones, emulsions, capillary surface
tension effects and lack of confinement for shallower zones.
Further, injecting steam creates water (condensate) in the
formation which is much less viscous than oil and which will
therefore be preferentially produced due to relative permeability
effects. Preferential production of water makes the oil production
or recovery more difficult.
[0004] Another approach to oil extraction is steam assisted gravity
drainage (SAGD). SAGD begins with the formation of a steam chamber
in the formation. The steam is injected at the chamber surface. The
heated oil flows down the walls of the chamber under the influence
of gravity and drains into the production well, thereby increasing
the size of the chamber. SAGD employs the countercurrent flow of
steam upwards into the reservoir and oil down and out of the
reservoir, which in certain situations can be relatively efficient,
and provide oil production rates high enough to provide favorable
economics. There are many possible SAGD geometries including single
well (injection and production from the same well) and dual or
multiple well. The wells may be either horizontal or vertical.
Generally horizontal wells are favored by producers because they
offer a greater (longer) exposure to the pay zone and thereby offer
increased production rates for highly viscous oils.
[0005] Yet another approach is the vapor extraction (VAPEX)
process, which proposes to combine a heated solvent (propane) with
hot water heated at surface to provide downhole heat. Because of
the use of hot water, this process suffers from the problems
mentioned above (countercurrent heat exchange, formation damage
problems with clays, emulsions, capillary pressure, water
treatment, water supply, reduced oil relative permeability due to
high water saturations and the like).
[0006] Oil wet reservoirs often require surfactants to alter the
wettability of the reservoir. When added to a flooding mechanism,
the oil can be removed in a more typical fashion. Unfortunately,
incorrect application of surfactants can damage a reservoir beyond
repair.
[0007] Existing heated solvent processes and Steam-assisted Gravity
Drainage (SAGD) processes have typically been avoided for
extraction from reservoirs that contain mobile water, as the mobile
water has been thought to be detrimental to all forms of enhanced
oil recovery (EOR). Thin pay zones have not been considered for
SAGD due to associated high heat losses to the surrounding
rocks.
[0008] In addition, existing heated solvent processes do not work
in the carbonate reservoirs due to substantially higher reservoir
pressure required which precludes the use of condensing vapor or
condensing solvent processes. Moreover, the use of heated propane
as the solvent, as used in processes like the VAPEX process, can
cause asphaltene plugging of the well, resulting in a substantial
loss of recoverable oil. Further, surfactants typically are cost
ineffective due to rock absorption rates.
[0009] While the application of heat or chemicals, either directly
to the reservoir or via the injection of heated solvents, has a
demonstrated effect in mobilizing oil for extraction, each of the
above processes suffers from the disadvantage of having either high
energy requirements for the generation of the steam and/or heated
solvents or a damaging reaction. The energy requirements are
typically met through the burning of large amounts of fuel, usually
natural gas. This leads to the emission of enormous amounts of
greenhouse gases such as carbon dioxide. For example, a 100,000
barrels (bbl) of oil per day SAGD facility requires 200,000-300,000
bbl water per day to be converted into steam. Thus, to recover
100,000 bbl oil per day using a natural gas burner system results
in producing more than 12 million pounds per day of carbon dioxide
emissions.
[0010] Therefore there is a need for an energy efficient and cost
effective process for stimulating production of oil, and which does
not suffer from the aforementioned problems, such as asphaltene
deposition/plugging.
BRIEF SUMMARY
[0011] In one embodiment, an improved extraction process for
recovering oil from an oil reservoir containing mobile water is
described. The extraction process establishes at least one
injection well and at least one production well. A first solvent
may be injected into the oil reservoir through the injection well
to form a combined first solvent and oil mixture. A first solvent
may be miscible in the oil while carried to the oil by the first
solvent. The combined first solvent and oil mixture may be
recovered from at least one production well to produce a first
recovered oil fraction and first solvent mixture. The extraction
process may then separate the first recovered oil fraction and
first solvent mixture to produce a first recovered oil fraction and
a separated first solvent. A second solvent may be injected into
the oil reservoir through the injection well (or another injection
well) to form a combined second solvent and residual oil mixture.
The combined second solvent and residual oil mixture may be
recovered from the production well (or another production well) to
produce a second recovered residual oil fraction and second solvent
mixture. The recovered residual oil fraction and second solvent
mixture may be separated to produce a second recovered oil fraction
and a separated second solvent.
[0012] In some embodiments, the first recovered oil fraction and
the second recovered oil fraction may be combined to produce a
combined recovered oil fraction, wherein the combined recovered oil
fraction may comprise a yield from about 50% to about 100%. The
first solvent may be at a temperature from about 10.degree. C. to
about 40.degree. C. during the step of injecting the first solvent
into the oil reservoir through the at least one injection well. The
second solvent may be at a temperature from about 10.degree. C. to
about 40.degree. C. during the step of injecting the second solvent
into the oil reservoir through the at least one injection well. The
first solvent and the second solvent may be at the temperature of
the oil reservoir.
[0013] In some embodiments, the first solvent may comprise a
methane, an ethane, a propane, a butane, a pentane, a hexane,
terpenes, benzene, toluene, aromatic hydrocarbons, water, and
combinations thereof. In some embodiments, the second solvent may
comprise a terpene or combination of terpenes, a turpentine, an
alcohol, an aromatic hydrocarbon, water, and combinations thereof.
The second solvent may comprise at least one diverting agent. The
diverting agent may be selected from the group consisting of a
viscous surfactant, a polymer, a CO.sub.2, and an acid. The
diverting agent may be present at a concentration from about 0.01%
to about 50%, by volume of a second solvent.
[0014] In another embodiment, an extraction process according to
the present disclosure may include injecting a first solvent into
the oil reservoir through the at least one injection well to form a
first mixture, the first mixture comprising the first solvent, a
first portion of mobile water, and a first portion of oil. The
extraction process may further include injecting a second solvent
into the oil reservoir through the at least one injection well to
form a second mixture, the second mixture comprising the second
solvent, a second portion of mobile water, and a second portion of
oil. The extraction process may further include injecting water
into the oil reservoir through the at least one injection well to
form a flooded injected water and oil mixture. The water may be a
water exogenous to the oil reservoir, or a water recovered from the
oil reservoir, or a combination thereof. The water may be injected
into the oil reservoir through the at least one injection well
after injecting the second solvent into the oil reservoir through
the at least one injection well.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The file of this patent contains at least one drawing
executed in color. Copies of this patent with color drawings will
be provided by the Patent and Trademark Office upon request and
payment of the necessary fee.
[0016] Exemplary embodiments of the present disclosure are
described herein with reference to the drawings, wherein like parts
are designated by like reference numbers, and wherein:
[0017] FIG. 1 illustrates an extraction process for recovering an
oil from an oil reservoir according to a specific example
embodiment of the disclosure;
[0018] FIG. 2 illustrates a system for extracting oil from an oil
reservoir according to a specific example embodiment of the
disclosure;
[0019] FIG. 3 illustrates a graphical representation of an oil
recovery with mobile water and without mobile water according to a
specific example embodiment of the disclosure;
[0020] FIG. 4 illustrates a graphical representation of an oil
recovery with mobile water and without mobile water according to a
specific example embodiment of the disclosure;
[0021] FIG. 5 illustrates oil recovery based on well configuration
according to a specific example embodiment of the disclosure;
[0022] FIG. 6A illustrates a thief water zone according to a
specific example embodiment of the disclosure; and
[0023] FIG. 6B illustrates a thief water zone according to a
specific example embodiment of the disclosure.
DETAILED DESCRIPTION
[0024] The present disclosure relates, in some embodiments, to an
extraction process for recovering oil from an oil reservoir or
reservoir that includes oil and mobile water. The extraction
process utilizes a first solvent and a second solvent, or a
combination thereof, which may be provided to or injected into the
oil reservoir at an injection well. The first and second solvent
may be injected at a reservoir temperature, at a reservoir
pressure, above reservoir pressure. According to some embodiments,
an extraction process using a first solvent and a second solvent
may desirably provide for a greater recovered oil fraction in
comparison to a corresponding extraction process not having the
first solvent and the second solvent. The extraction process
described herein using a first solvent and a second solvent may
desirably provide for a displacement of mobile water within an oil
reservoir, which may increase propagation, diffusion, contact, or a
combination thereof, of the first solvent or the second solvent
with the oil. The first solvent, the second solvent, the oil, the
water, or combinations thereof, may be recovered through one or
more production wells.
[0025] As discussed above, the first solvent and the second solvent
may be injected into the oil reservoir at one or more injection
wells at a reservoir temperature or the temperature of the oil
reservoir. For example, since an oil reservoir may have a
temperature from about 10.degree. C. to about 40.degree. C., a
first solvent, a second solvent, or a combination thereof, may be
injected into the oil reservoir at a temperature from about
10.degree. C. to about 40.degree. C. By injecting the first and/or
second solvent at the oil reservoir temperature, the extraction
process may advantageously increase a yield of a recovered oil
fraction.
[0026] Example embodiments are shown in FIGS. 1-6B. FIG. 1
illustrates an extraction process for recovering an oil from an oil
reservoir containing mobile water. FIG. 2 illustrates a system for
extracting oil from an oil reservoir. FIG. 3 illustrates a
graphical representation of an oil recovery with mobile water and
without mobile water according to a specific example embodiment of
the disclosure. FIG. 4 illustrates a graphical representation of an
oil recovery with mobile water and without mobile water. FIG. 5
illustrates oil recovery based on well configuration. FIGS. 6A and
6B illustrate a thief water zone according to a specific example
embodiment of the disclosure.
[0027] FIG. 1 illustrates an extraction process 100 for recovering
oil from an oil reservoir containing mobile water. The extraction
process 100 may comprise the steps of a) establishing one or more
injection wells and one or more production wells 110, b) injecting
a first solvent into the oil reservoir through the at least one
injection well to form a first mixture, the first mixture
comprising the first solvent, a first portion of mobile water, and
a first portion of oil 120, recovering the first mixture from the
at least one production well to produce a first recovered oil
mixture, the first recovered oil mixture comprising the first
solvent, the first portion of the mobile water, and the first
portion of oil 130; (d) separating the first recovered oil mixture
to produce a first recovered oil fraction that is separated from
the first portion of mobile water and the first solvent 140, and
recovering the first recovered oil 145. Additionally, the process
may include a step of recycling the separated first solvent
135.
[0028] The above described extraction process 100 also includes the
steps of (e) injecting a second solvent into the oil reservoir
through the at least one injection well to form a second mixture,
the second mixture comprising the second solvent, a second portion
of mobile water, and a second portion of oil 150; (f) recovering
the second mixture from the at least one production well to produce
a second recovered oil mixture, the second recovered oil mixture
comprising the second solvent, the second portion of the mobile
water, and the second portion of oil 160; and (g) separating the
second recovered oil mixture to produce a second recovered oil
fraction that is separated from the second portion of mobile water
and the second solvent 170. The second recovered oil fraction may
comprise reservoir water. The combined recovered oil fractions may
provide for a yield from about 50% to about 100%. The yield may
include percent oil contained in the oil reservoir at the
initiation of the oil recovery process. For example, the combined
recovered oil fractions may provide for a yield from about 50% to
about 90% of the oil present in the oil reservoir prior to the
extraction process, within the first 10 years of oil recovery, but
may incrementally increases to a complete recovery, or a yield of
100%, over a 25 year period. The first recovered oil fraction and
the second recovered oil fraction may be combined 190.
Additionally, the separated second solvent may be recycled 165.
[0029] The injecting of the first solvent into the oil reservoir
120 and the injecting of the second solvent into the oil reservoir
150 may be performed iteratively, concurrently, and sequentially.
In some embodiments, the second solvent may not be used. In other
embodiments, the first solvent may be injected and then the second
solvent may be injected into the oil reservoir. The second solvent
may desirably provide for asphaltene dissolution, which may
mitigate an effect of asphaltene deposition. In some embodiments,
the first solvent may be combined with the second solvent and then
the combined solvent mixture may be injected into the oil
reservoir. The first solvent and the second solvent may be mixed at
various ratios and then injected into the oil reservoir. For
example, the ratio of first solvent to second solvent may include
from about 1:99 to about 1:1. Additionally, the ratio of first
solvent to second solvent may include from about 1:1 to about
99:1.
[0030] The first solvent and the second solvent may be injected
into the oil reservoir at a temperature from about 10.degree. C. to
about 40.degree. C. and at a pressure from about 50 kPa to about
1500 kPa above original reservoir pressure. Additionally, the
extraction process may proceed without the use of surfactants,
where the use thereof may require additional purification steps to
remove the surfactants from the final oil product(s). Therefore,
the extraction process 100 described above may desirably provide
for advantages over conventional processes, the advantages
including higher recovered oil yields, lower capital requirements,
solvent injections operating below fracture pressure, and
maintenance of overall reservoir pressure. Also, the dual solvent
extraction process 100 described above may displace mobile
reservoir water and propagate deep within the oil reservoir, which
may provide for a higher yield of recovered oil contacted by the
mobile water that would be otherwise inaccessible to conventional
processes.
[0031] The extraction process 100 may be suitable for extracting
oil, including a heavy oil and a light oil, from oil reservoirs
such as carbonate rock deposits (e.g., dolomite or limestone
reservoirs) and oil wet reservoirs, but may also be used in other
formations such as oil sands deposits. The hybrid cold solvent
process 100 may employ combinations of solvents that can be
optimized for water wet, oil wet, and fractionally wet
reservoirs.
[0032] The above described extraction process 100 may also include
a water flooding or water injection stage. Water injection prior to
solvent injection may be desirable in some cases where mobile flow
pathways between the injection well and the production well are not
available. Water may also be injected into the oil reservoir after
the step of injecting the second solvent into the oil reservoir
150; and after the step of recovering the combined second solvent/
oil mixture 160. Water injection may be done with fresh water or by
mobile water recovered from the extraction process 100. Late water
injection may be a viable solvent injection step.
[0033] The separation of the first recovered oil mixture to produce
a first recovered oil fraction that is separated from the first
portion of mobile water and the first solvent 140 or the separation
of the second recovered oil mixture to produce a second recovered
oil fraction that is separated from the second portion of mobile
water and the second solvent 170 may also include purifying the
first solvent or the second solvent. The separation may include
separation from water and then recovering the solvent from the
produced oil. The water may be recovered mobile water. For example,
the recovered first solvent or recovered second solvent may be
distilled before recycling them back into the extraction process
100.
[0034] The extraction process described above 100 may facilitate
the removal of an asphaltene deposition in the oil reservoir, which
may increase the recovered oil yield, quality, and purity.
Reducing, removing, preventing, and/or mitigating an asphaltene
deposition may desirably provide for the reduction and/or avoidance
of plugging or clogging of pores and may maintain open flow
pathways to the production well, thereby permitting an increased
ability for extraction of the oil within the reservoir.
[0035] The extraction process described above 100 may be performed
in batch injections, continuous injections, or combinations
thereof. Additionally, solvent injection methods, injection
pressures, and rates may be adjusted periodically or
instantaneously depending on the oil recovery yield from the oil
reservoir.
[0036] The first solvent and the second solvent from the process
above 100 may be chosen for ease of use, recyclability, commodity
price, and availability. For example, the first solvent may include
a light hydrocarbon such as a methane, an ethane, a propane, a
butane, a pentane, a hexane, and combinations thereof. Use of a
hydrocarbon solvent comprising a propane as a first solvent in an
extraction process may provide for an in situ de-asphalting of an
oil, which may provide for a production of a commercially enhanced
product for sales.
[0037] The second solvent may be a non-petroleum based "green"
solvent. For example, the non-petroleum based green solvent may be
derived from a processed biomass or be a by-product of a wood, a
pulp, a paper industry, or a combination thereof. The second
solvent may include biomass based terpenes such as limonene. The
second solvent may include a terpene or combination of terpenes, a
turpentine, an alcohol, an aromatic hydrocarbon, or a combination
thereof. Terpenes may be hemiterpenes, monoterpenes,
sesquiterpenes, diterpenes, triterpenes, tetraterpenes, and
combinations thereof. Alcohols may be methanol, ethanol, propanol,
isopropanol, butanol, and combinations thereof. An aromatic
hydrocarbon may be a benzene, a toluene, a xylene, and combinations
thereof.
[0038] The second solvent may include a diverting agent, which may
desirably provide for a stimulation of the oil reservoir, which may
provide for a uniform injectivity profile of the second solvent in
comparison to a corresponding second solvent not having the
diverting agent. The diverting agent may be a viscous surfactant, a
polymer, a CO.sub.2, or combinations thereof. An extraction process
comprising a diverting agent may desirably provide for an increase
in a sweep efficiency, an increase in a yield of recovered oil, or
a combination thereof in comparison to a corresponding extraction
process not having the diverting agent. The concentration of
diverting agent in the second solvent may range from about 1% to
about 50%, by volume of the second solvent. For example, a second
solvent may comprise a CO.sub.2 at a concentration of about 10%, by
volume of the second solvent.
[0039] The first and second solvents may have the same or different
viscosities. For example, the second solvent may have a higher
viscosity than the first solvent, which may desirably provide for
an increased recovered oil percentage than extraction processes
using a second solvent comprising a lower viscosity than the first
solvent. In this case, using the less viscous first solvent to
establish a communication between the injection well and the
production well, followed by an injection of the more viscous
second solvent may compensate for channeling tendencies in the oil
reservoir formation. Additionally, it may be possible to ensure
that deposition of asphaltene is mitigated and a high percentage of
the oil is contacted and recovered.
[0040] FIG. 2 illustrates a system 200 for extracting oil from an
oil reservoir. The system 200 includes a first solvent reservoir
210, an injection well 230, a second solvent reservoir 220, an oil
reservoir 240, a production well 250, production treating facility
255, and a recovered oil reservoir 280. The production treating
facility 255 may separate first solvent(s) from a first recovered
oil, separate water from the first recovered oil, separate second
solvent(s) from the second recovered solvent and oil mixture,
separate water from the second recovered solvent and oil mixture,
distill recovered solvents, recycle the first solvent, recycle the
second solvent, distill recovered oil, purify recovered oil, and
combinations thereof.
[0041] In the above described system 200, the injection well 230 is
connected to the first solvent reservoir 210 through a first
solvent stream 215. The injection well 230 is connected to the
second solvent reservoir 220 through a second solvent stream 225.
The oil reservoir 240 is connected to the injection well 230
through an injection stream 235. The production well 250 is
connected to the oil reservoir 240 through a recovery stream 245.
Optionally, the production treating facility 255 may be connected
to the second solvent reservoir 220 through a second solvent
recycle stream 260. Optionally, the production treating facility
255 may be connected to the first solvent reservoir 210 through a
first solvent recycle stream 270. The production treating facility
255 may be connected to the production well(s) 250 through the oil
recovery stream 265. The recovered oil reservoir 280 may be
connected to production treating facility 255 through a recovered
oil stream 275.
[0042] Additionally, in the system 200 described above, the
injection well 230 is configured to receive a first solvent from
the first solvent reservoir 210 through the first solvent stream
215. The injection well 230 is configured to receive a second
solvent from the second solvent reservoir 220 through the second
solvent stream 225. The production treating facility 255 is
configured to receive an oil recovery stream 265 from the
production well(s) 250. The recovered oil reservoir 280 is
configured to receive a recovered oil from the production treating
facility 255 through a recovered oil stream 275. The first solvent
reservoir 210 is configured to receive a recycled first solvent
from the production treating facility 255 through the first solvent
recycle stream 270. The second solvent reservoir 220 is configured
to receive a recycled second solvent from the production treating
facility 255 through the second solvent recycle stream 260. In some
embodiments, the system 200 may comprise a surface processing
facility. The surface processing facility may derive water from the
recovered oil, may recycle solvent, may refine recovered oil, and
combinations thereof. A system may be configured to suit the
situation and improve the results of the process. For example,
components of the system may be adjusted including vertical spacing
of components, horizontal spacing of components, length in between
components, length of system, relative elevation of the oil
reservoir, vertical displacement of the production well(s),
vertical displacement of the injection well(s), and combinations
thereof.
[0043] As will be understood by those skilled in the art who have
the benefit of the instant disclosure, other equivalent or
alternative compositions, devices, processes, methods, and systems
for extracting an oil form an oil reservoir comprising a mobile
water can be envisioned without departing from the description
contained herein. Accordingly, the manner of carrying out the
disclosure as shown and described is to be construed as
illustrative only.
[0044] Persons skilled in the art may make various changes in the
shape, size, number, and/or arrangement of parts without departing
from the scope of the instant disclosure. For example, the position
and number of solvents and extractions may be varied. In some
embodiments, solvents may be interchangeable. In addition, the size
of a device and/or system may be scaled up or down to suit the
needs and/or desires of a practitioner. Each disclosed process,
method and method step may be performed in association with any
other disclosed method or method step and in any order according to
some embodiments. Where the verb "may" appears, it is intended to
convey an optional and/or permissive condition, but its use is not
intended to suggest any lack of operability unless otherwise
indicated. Where open terms such as "having" or "comprising" are
used, one of ordinary skill in the art having the benefit of the
instant disclosure will appreciate that the disclosed features or
steps optionally may be combined with additional features or steps.
Such option may not be exercised and, indeed, in some embodiments,
disclosed systems, compositions, apparatuses, and/or methods may
exclude any other features or steps beyond those disclosed herein.
Elements, compositions, devices, systems, methods, and method steps
not recited may be included or excluded as desired or required.
Persons skilled in the art may make various changes in methods of
preparing and using a composition, device, and/or system of the
disclosure.
[0045] Also, where ranges have been provided, the disclosed
endpoints may be treated as exact and/or approximations as desired
or demanded by the particular embodiment. Where the endpoints are
approximate, the degree of flexibility may vary in proportion to
the order of magnitude of the range. For example, on one hand, a
range endpoint of about 50 in the context of a range of about 5 to
about 50 may include 50.5, but not 52.5 or 55 and, on the other
hand, a range endpoint of about 50 in the context of a range of
about 0.5 to about 50 may include 55, but not 60 or 75. In
addition, it may be desirable, in some embodiments, to mix and
match range endpoints. Also, in some embodiments, each figure
disclosed (e.g., in one or more of the examples, tables, and/or
drawings) may form the basis of a range (e.g., depicted value +/-
about 10%, depicted value +/- about 50%, depicted value +/- about
100%) and/or a range endpoint. With respect to the former, a value
of 50 depicted in an example, table, and/or drawing may form the
basis of a range of, for example, about 45 to about 55, about 25 to
about 100, and/or about 0 to about 100. Disclosed percentages are
volume percentages except where indicated otherwise.
[0046] All or a portion of a system for extraction and recovery of
oil from reservoirs containing mobile water may be configured and
arranged to be disposable, serviceable, interchangeable, and/or
replaceable. These equivalents and alternatives along with obvious
changes and modifications are intended to be included within the
scope of the present disclosure. Accordingly, the foregoing
disclosure is intended to be illustrative, but not limiting, of the
scope of the disclosure as illustrated by the appended claims.
[0047] The title, abstract, background, and headings are provided
in compliance with regulations and/or for the convenience of the
reader. They include no admissions as to the scope and content of
prior art and no limitations applicable to all disclosed
embodiments.
EXAMPLES
[0048] Some specific example embodiments of the disclosure may be
illustrated by one or more of the examples provided herein.
Example 1
Mobile Water Compared to Immobile Water Start-Up Comparison at 10 m
Apart
[0049] In a heavy oil reservoir that is oil wet, a solvent cocktail
was used to displace oil. In this example, one production well was
placed between two injection wells and the distance between
injection well and production well was 10 m. The recovery factors
with and without mobile water present are shown in FIG. 3.
Example 2
Mobile Water Compared to Immobile Water Start-Up Comparison at 40 m
Apart
[0050] In a heavy oil reservoir that is oil wet, a solvent cocktail
was used to displace oil. In this example one production well was
placed between two injection wells and the distance between each
injection well and production well was 10 m. The recovery factors
with and without mobile water present are shown in FIG. 4. As shown
in FIG. 4, increasing the distance between the injector and the
producer from 10 m to 40 m makes production less feasible unless
mobile water is present.
Example 3
Solvent Composition Compared to Optimal Well Configuration
[0051] In a similar scenario as in Example 1, production
acceleration and improved sweep efficiency can be reached if the
producer is augmented by the injection of a second producer at a
different depth (higher or lower in the formation depending on the
solvent cocktail composition). This additional well may create new
displacement pathways and may improve sweep efficiency by order of
magnitude in respect to time. As shown in FIG. 5, employing a
staggered well configuration may provide for a desirable oil
recovery.
[0052] Well placement near a water/oil interface may allow fast
spreading of a solvent and may allow access to very large volumes
of oil. This may accelerate production and may be an advantageous
option compared to a VAPEX type process.
Example 4
Thief Water Zone Presence
[0053] As shown in FIGS. 6A and 6B, the presence of a water thief
zone may be taken advantage of to carry the solvent from injector
to producer, add oil/solvent contact and accelerate oil production.
In such cases it is anticipated that the production of water will
be higher than previous cases.
* * * * *