U.S. patent application number 13/233691 was filed with the patent office on 2012-03-22 for methods for producing oil and/or gas.
This patent application is currently assigned to SHELL OIL COMPANY. Invention is credited to Paulus Maria BOERRIGTER, Rouhollah FARAJZADEH, Leonardus Bartholomeus Maria WASSING.
Application Number | 20120067571 13/233691 |
Document ID | / |
Family ID | 44719390 |
Filed Date | 2012-03-22 |
United States Patent
Application |
20120067571 |
Kind Code |
A1 |
BOERRIGTER; Paulus Maria ;
et al. |
March 22, 2012 |
METHODS FOR PRODUCING OIL AND/OR GAS
Abstract
A method for producing oil from an underground formation
comprising injecting an enhanced oil recovery formulation into a
first well in the formation, the enhanced oil recovery formulation
comprising a foam; floating the foam on top of the oil, in order to
force the oil towards a second well in the formation; and producing
the oil and/or gas from the second well.
Inventors: |
BOERRIGTER; Paulus Maria;
(Mina Al Fahal, OM) ; FARAJZADEH; Rouhollah;
(Rijswijk, NL) ; WASSING; Leonardus Bartholomeus
Maria; (Rijswijk, NL) |
Assignee: |
SHELL OIL COMPANY
Houston
TX
|
Family ID: |
44719390 |
Appl. No.: |
13/233691 |
Filed: |
September 15, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61384121 |
Sep 17, 2010 |
|
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|
Current U.S.
Class: |
166/270.1 |
Current CPC
Class: |
E21B 43/168
20130101 |
Class at
Publication: |
166/270.1 |
International
Class: |
E21B 43/22 20060101
E21B043/22 |
Claims
1. A method for producing oil from an underground formation
comprising: injecting an enhanced oil recovery formulation into a
first well in the formation, the enhanced oil recovery formulation
comprising a foam; floating the foam on top of the oil, in order to
force the oil towards a second well in the formation; and producing
the oil and/or gas from the second well.
2. The method of claim 1, wherein the first well further comprises
a first array of wells, and the second well further comprises a
second array of wells, wherein a well in the first array of wells
is at a distance of 10 meters to 1 kilometer from one or more
adjacent wells in the second array of wells.
3. The method of claim 1, wherein the underground formation is
beneath a body of water.
4. The method of claim 1, wherein the foam is injected into one or
more fractures in the formation.
5. The method of claim 1, further comprising injecting a second
enhanced oil recovery formulation into the formation, the second
enhanced oil recovery formulation being denser than the oil,
further comprising floating the oil on the second enhanced oil
recovery formulation.
6. The method of claim 2, wherein the first array of wells
comprises from 5 to 500 wells, and the second array of wells
comprises from 5 to 500 wells.
7. The method of claim 1, wherein the enhanced oil recovery
formulation comprises gas and a surfactant.
8. The method of claim 1, wherein the enhanced oil recovery
formulation comprises a gas selected from the group consisting of
nitrogen, carbon dioxide, natural gas, and hydrocarbon gases other
than natural gas having from one to four carbon atoms.
9. The method of claim 5, wherein the second enhanced oil recovery
formulation comprises a carbon disulfide formulation.
10. The method of claim 1, wherein the underground formation
comprises an oil having a viscosity from 100 to 5,000,000
centipoise.
11. The method of claim 1, wherein the enhanced oil recovery
formulation is less dense than the oil.
12. The method of claim 1, wherein the oil floats on the enhanced
oil recovery formulation.
Description
PRIORITY CLAIM
[0001] This application claims priority to U.S. Provisional
Application No. 61/384,121 entitled "METHODS OF PRODUCING OIL
AND/OR GAS" filed on Sep. 17, 2010.
FIELD OF THE INVENTION
[0002] The present disclosure relates to methods for producing oil
and/or gas.
BACKGROUND OF THE INVENTION
[0003] Enhanced Oil Recovery (EOR) may be used to increase oil
recovery in fields worldwide. There are three main types of EOR,
thermal, chemical/polymer and gas injection, which may be used to
increase oil recovery from a reservoir, beyond what can be achieved
by conventional means--possibly extending the life of a field and
boosting the oil recovery factor.
[0004] Thermal enhanced recovery works by adding heat to the
reservoir. The most widely practiced form is a steam-drive, which
reduces oil viscosity so that it can flow to the producing wells.
Chemical flooding increases recovery by reducing the capillary
forces that trap residual oil. Polymer flooding improves the sweep
efficiency of injected water. Miscible injection works in a similar
way to chemical flooding. By injecting a fluid that is miscible
with the oil, trapped residual oil can be recovered.
[0005] Referring to FIG. 1, there is illustrated prior art system
100. System 100 includes underground formation 102, underground
formation 104, underground formation 106, and underground formation
108. Production facility 110 is provided at the surface. Well 112
traverses formations 102 and 104, and terminates in formation 106.
The portion of formation 106 is shown at 114. Oil and gas are
produced from formation 106 through well 112, to production
facility 110. Gas and liquid are separated from each other, gas is
stored in gas storage 116 and liquid is stored in liquid storage
118.
[0006] PCT Patent Application WO 2010/40202 discloses a
Steam-Over-Solvent Injection in Fractured Reservoirs (SOS-FR)
carried out by treating a fractured hydrocarbon bearing formation
penetrated by a well with a first phase of injecting a formation
compatible aqueous fluid into the fractured hydrocarbon bearing
formation through the well, a second phase of injecting a
hydrocarbon solvent into the fractured hydrocarbon bearing
formation through the well and at least a third phase of repeating
the first phase after the second phase. PCT Patent Application WO
2010/40202 is herein incorporated by reference in its entirety.
[0007] U.S. Patent Application Publication 2009/0260809 discloses
methods of generating subsurface heat for treatment of a
hydrocarbon containing formation. Methods include providing steam
to at least a portion of a hydrocarbon containing formation from a
plurality of locations in a wellbore. The steam is hotter than a
temperature of the portion. The steam is heated in the wellbore by
combusting a stream comprising hydrogen sulfide in the wellbore.
Heat from the combustion transfers to the steam. The steam provided
the portion at a first location in the wellbore is hotter than
steam provided at a second location in the wellbore along the
length of the wellbore, where the first location is further from a
surface of the formation than the second location along the length
of the wellbore. U.S. Patent Application Publication 2009/0260809
is herein incorporated by reference in its entirety.
[0008] U.S. Patent Application Publication 2009/0056941 discloses
method for producing oil and/or gas comprising a method for
producing oil from an underground formation comprising injecting an
enhanced oil recovery formulation and a gas into a first well in
the formation; forming a mixture comprising the enhanced oil
recovery formulation and the oil in the formation; forming a gas
cap with the injected gas; forcing the formulation and oil mixture
towards a second well in the formation; and producing the
formulation and oil mixture from the second well. U.S. Patent
Application Publication 2009/0056941 is herein incorporated by
reference in its entirety.
[0009] U.S. Pat. No. 4,232,741 discloses that portions of a
subterranean reservoir are temporarily plugged by injecting an
aqueous liquid solution which contains nitrogen gas-generating
reactants, a foaming surfactant and a pH controlling system
arranged so that the solution remains relatively unreactive within
the well but forms a relatively immobile foam within the pores or
other openings within the reservoir formation. U.S. Pat. No.
4,232,741 is herein incorporated by reference in its entirety.
[0010] There is a need in the art for improved systems and methods
for enhanced oil recovery. There is a further need in the art for
improved systems and methods for enhanced oil recovery using gas
oil gravity drainage. There is a further need in the art for
improved systems and methods for enhanced oil recovery in fractured
reservoirs.
SUMMARY OF THE INVENTION
[0011] In one aspect, the invention provides a method for producing
oil from an underground formation comprising injecting an enhanced
oil recovery formulation into a first well in the formation, the
enhanced oil recovery formulation comprising a foam; floating the
foam on top of the oil, in order to force the oil towards a second
well in the formation; and producing the oil and/or gas from the
second well.
[0012] Advantages of the invention include one or more of the
following:
[0013] Improved systems and methods for enhanced recovery of
hydrocarbons from a formation with a gas and/or a foam.
[0014] Improved systems and methods for enhanced recovery of
hydrocarbons from a formation with a gas lighter than oil and a
liquid heavier than oil.
[0015] Improved compositions and/or techniques for secondary and/or
tertiary recovery of hydrocarbons.
[0016] Improved systems and methods for enhanced oil recovery.
[0017] Improved systems and methods for enhanced oil recovery in
fractured reservoirs.
[0018] Improved systems and methods for enhanced oil recovery using
a foam.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 illustrates an oil and/or gas production system.
[0020] FIG. 2 illustrates a well pattern.
[0021] FIG. 3 illustrates an oil and/or gas production systems.
[0022] FIG. 4 illustrates an oil and/or gas production method.
[0023] FIG. 5 illustrates an oil and/or gas production system.
[0024] FIG. 6 illustrates an oil and/or gas production system.
DETAILED DESCRIPTION OF THE INVENTION
[0025] FIG. 2:
[0026] Referring now to FIG. 2, in some embodiments, an array of
wells 200 is illustrated. Array 200 includes well group 202
(denoted by horizontal lines) and well group 204 (denoted by
diagonal lines).
[0027] Each well in well group 202 has horizontal distance 230 from
the adjacent well in well group 202. Each well in well group 202
has vertical distance 232 from the adjacent well in well group
202.
[0028] Each well in well group 204 has horizontal distance 236 from
the adjacent well in well group 204. Each well in well group 204
has vertical distance 238 from the adjacent well in well group
204.
[0029] Each well in well group 202 is distance 234 from the
adjacent wells in well group 204. Each well in well group 204 is
distance 234 from the adjacent wells in well group 202.
[0030] In some embodiments, each well in well group 202 is
surrounded by four wells in well group 204. In some embodiments,
each well in well group 204 is surrounded by four wells in well
group 202.
[0031] In some embodiments, horizontal distance 230 is from about 5
to about 1000 meters, or from about 10 to about 500 meters, or from
about 20 to about 250 meters, or from about 30 to about 200 meters,
or from about 50 to about 150 meters, or from about 90 to about 120
meters, or about 100 meters.
[0032] In some embodiments, vertical distance 232 is from about 5
to about 1000 meters, or from about 10 to about 500 meters, or from
about 20 to about 250 meters, or from about 30 to about 200 meters,
or from about 50 to about 150 meters, or from about 90 to about 120
meters, or about 100 meters.
[0033] In some embodiments, horizontal distance 236 is from about 5
to about 1000 meters, or from about 10 to about 500 meters, or from
about 20 to about 250 meters, or from about 30 to about 200 meters,
or from about 50 to about 150 meters, or from about 90 to about 120
meters, or about 100 meters.
[0034] In some embodiments, vertical distance 238 is from about 5
to about 1000 meters, or from about 10 to about 500 meters, or from
about 20 to about 250 meters, or from about 30 to about 200 meters,
or from about 50 to about 150 meters, or from about 90 to about 120
meters, or about 100 meters.
[0035] In some embodiments, distance 234 is from about 5 to about
1000 meters, or from about 10 to about 500 meters, or from about 20
to about 250 meters, or from about 30 to about 200 meters, or from
about 50 to about 150 meters, or from about 90 to about 120 meters,
or about 100 meters.
[0036] In some embodiments, array of wells 200 may have from about
10 to about 1000 wells, for example from about 5 to about 500 wells
in well group 202, and from about 5 to about 500 wells in well
group 204.
[0037] In some embodiments, array of wells 200 is seen as a top
view with well group 202 and well group 204 being vertical wells
spaced on a piece of land. In some embodiments, array of wells 200
is seen as a cross-sectional side view with well group 202 and well
group 204 being horizontal wells spaced within a formation.
[0038] The recovery of oil and/or gas with array of wells 200 from
an underground formation may be accomplished by any known method.
Suitable methods include subsea production, surface production,
primary, secondary, or tertiary production. The selection of the
method used to recover the oil and/or gas from the underground
formation is not critical.
[0039] In some embodiments, oil and/or gas may be recovered from a
formation into a well, and flow through the well and flowline to a
facility. In some embodiments, enhanced oil recovery, with the use
of an agent for example steam, water, a surfactant, a gas, a foam,
a polymer flood, and/or a miscible agent, may be used to increase
the flow of oil and/or gas from the formation.
[0040] In some embodiments, an enhanced oil recovery agent is
injected into well group 202, and oil is recovered from well group
204. In some embodiments, well group 202 may be used for injecting
a enhanced oil recovery agent, and well group 204 may be used for
producing oil and/or gas from the formation for a first time
period; then well group 204 may be used for injecting a enhanced
oil recovery agent, and well group 202 may be used for producing
oil and/or gas from the formation for a second time period, where
the first and second time periods comprise a cycle.
[0041] In some embodiments, multiple cycles may be conducted which
include alternating well groups 202 and 204 between injecting a
enhanced oil recovery agent, and producing oil and/or gas from the
formation, where one well group is injecting and the other is
producing for a first time period, and then they are switched for a
second time period.
[0042] In some embodiments, a cycle may be from about 12 hours to
about 1 year, or from about 3 days to about 6 months, or from about
5 days to about 3 months.
[0043] In some embodiments, oil as present in the formation prior
to the injection of any enhanced oil recovery agents has a
viscosity of at least about 100 centipoise, or at least about 500
centipoise, or at least about 1000 centipoise, or at least about
2000 centipoise, or at least about 5000 centipoise, or at least
about 10,000 centipoise. In some embodiments, oil as present in the
formation prior to the injection of any enhanced oil recovery
agents has a viscosity of up to about 5,000,000 centipoise, or up
to about 2,000,000 centipoise, or up to about 1,000,000 centipoise,
or up to about 500,000 centipoise.
[0044] Releasing at least a portion of the enhanced oil recovery
agent and/or other liquids and/or gases may be accomplished by any
known method. One suitable method is injecting the enhanced oil
recovery formulation into a single conduit in a single well,
allowing the formulation to soak, and then pumping out at least a
portion of the formulation with gas and/or liquids. Another
suitable method is injecting the enhanced oil recovery formulation
into a first well, and pumping out at least a portion of the
enhanced oil recovery formulation with gas and/or liquids through a
second well. The selection of the method used to inject at least a
portion of the enhanced oil recovery formulation and/or other
liquids and/or gases is not critical.
[0045] In some embodiments, the enhanced oil recovery formulation
and/or other liquids and/or gases may be pumped into a formation at
a pressure up to the fracture pressure of the formation.
[0046] FIG. 3:
[0047] Referring now to FIG. 3, in some embodiments of the
invention, system 400 is illustrated. System 400 includes
underground formation 402, formation 404, formation 406, and
formation 408. Production facility 410 is provided at the surface.
Well 412 traverses formation 402 and 404 has openings at formation
406. Portions of formation 414 may be optionally fractured and/or
perforated. As oil and gas is produced from formation 406 it enters
portions 414, and travels up well 412 to production facility 410.
Gas and liquid may be separated, and gas may be sent to gas storage
416, and liquid may be sent to liquid storage 418. Production
facility 410 is able to produce and/or store enhanced oil recovery
formulation, which may be produced and stored in production/storage
430.
[0048] Enhanced oil recovery formulation is pumped down well 432,
to portions 434 of formation 406. Enhanced oil recovery formulation
traverses formation 406 to aid in the production of oil and gas,
and then the enhanced oil recovery formulation, oil and/or gas may
all be produced to well 412, to production facility 410. Enhanced
oil recovery formulation may then be recycled, by re-injecting the
formulation into well 432.
[0049] In some embodiments, a quantity of enhanced oil recovery
formulation or enhanced oil recovery formulation mixed with other
components may be injected into well 432, followed by another
component to force enhanced oil recovery formulation or enhanced
oil recovery formulation mixed with other components across
formation 406, for example air; water in gas or liquid form; carbon
dioxide; nitrogen; water mixed with one or more salts, polymers,
and/or surfactants; carbon dioxide; other gases; other liquids;
and/or mixtures thereof.
[0050] In some embodiments, well 412 which is producing oil and/or
gas is representative of a well in well group 202, and well 432
which is being used to inject enhanced oil recovery formulation is
representative of a well in well group 204.
[0051] In some embodiments, well 412 which is producing oil and/or
gas is representative of a well in well group 204, and well 432
which is being used to inject enhanced oil recovery formulation is
representative of a well in well group 202.
[0052] FIG. 4:
[0053] Referring now to FIG. 4, in some embodiments of the
invention, system 500 is illustrated. System 500 includes
underground formation 502, formation 504, formation 506, and
formation 508. Production facility 510 is provided at the surface.
Well 512 traverses formation 502 and 504 has openings at formation
506. Gas and/or a gas containing foam may be injected into and then
trapped in the upper portions of formation 506, which may include
dome structure 514, for example since the gas is floating on a
denser oil in the formation. As oil and gas is produced from the
lower portions 534 of formation 506, it travels up well 532 to
production facility 510. Gas and liquid may be separated, and gas
may be sent to gas storage 516, and liquid may be sent to liquid
storage 518. Production facility 510 is able to produce and/or
store enhanced oil recovery formulation, which may be produced and
stored in production/storage 530.
[0054] Enhanced oil recovery formulation is pumped down well 512,
to portions 514 of formation 506. Enhanced oil recovery formulation
is lighter than the oil and/or gas in formation 506, and due to the
buoyancy of the oil recovery formulation, oil and/or gas is trapped
in the lower portions 534 of formation 506. Enhanced oil recovery
formulation traverses formation 506 to aid in the production of oil
and gas, and then the oil and/or gas in formation 506 and enhanced
oil recovery formulation may all be produced to well 532, to
production facility 510.
[0055] Enhanced oil recovery formulation may then be recycled, by
re-injecting the formulation into well 512.
[0056] In some embodiments, enhanced oil recovery formulation
includes gas, gas mixed with water and a surfactant to form a foam,
or other light gases or liquids, for example natural gas, methane,
carbon dioxide and/or nitrogen.
[0057] In some embodiments, well 532 which is producing oil and/or
gas is representative of a well in well group 202, and well 512
which is being used to inject enhanced oil recovery formulation is
representative of a well in well group 204.
[0058] In some embodiments, well 532 which is producing oil and/or
gas is representative of a well in well group 204, and well 512
which is being used to inject enhanced oil recovery formulation is
representative of a well in well group 202.
[0059] FIG. 5:
[0060] Referring now to FIG. 5, in some embodiments of the
invention, system 600 is illustrated. System 600 includes
underground formation 602, formation 604, formation 606, and
formation 608. Production facility 610 is provided at the surface.
Well 612 traverses formation 602 and 604 has openings at formation
606. The oil and/or gas may be trapped in the upper portions of
formation 606, which may include dome structure 614, for example
since the oil and/or gas is floating on a denser enhanced oil
recovery formulation. As oil and gas is produced from the upper
portions of formation 606, which may include dome 614, it travels
up well 612 to production facility 610. Gas and liquid may be
separated, and gas may be sent to gas storage 616, and liquid may
be sent to liquid storage 618. Production facility 610 is able to
produce and/or store enhanced oil recovery formulation, which may
be produced and stored in production/storage 630.
[0061] Enhanced oil recovery formulation is pumped down well 632,
to portions 634 of formation 606. Enhanced oil recovery formulation
is denser than the oil and/or gas in dome 614, and causes a
buoyancy for oil and/or gas to trap it in the upper portions of
formation 606, including dome 614. Enhanced oil recovery
formulation traverses formation 606 to aid in the production of oil
and gas, and then the enhanced oil recovery formulation may all be
produced to well 612, to production facility 610. Enhanced oil
recovery formulation may then be recycled, by re-injecting the
formulation into well 632.
[0062] In some embodiments, enhanced oil recovery formulation
includes water, water with additives such as polymers, alkalis,
and/or surfactants, or other dense liquids, for example carbon
disulfide or carbon disulfide formulations.
[0063] In some embodiments, well 612 which is producing oil and/or
gas is representative of a well in well group 202, and well 632
which is being used to inject enhanced oil recovery formulation is
representative of a well in well group 204.
[0064] In some embodiments, well 612 which is producing oil and/or
gas is representative of a well in well group 204, and well 632
which is being used to inject enhanced oil recovery formulation is
representative of a well in well group 202.
[0065] FIG. 6:
[0066] Referring now to FIG. 6, in some embodiments of the
invention, system 700 is illustrated. System 700 includes
underground formation 702, formation 704, formation 706, and
formation 708. Production facility 710 is provided at the surface.
Well 712 traverses formation 702 and 704 has openings at formation
706. Portions of formation 706 form dome 714, which may trap
liquids and/or gases. Formation 706 has fractures, karsts, and/or
vugs 707 which provide a low resistance fluid path from well 712 to
well 732, and vice versa. As liquids and/or gases are produced from
formation 706, they travel up well 732 to production facility 710.
Gas and liquid may be separated, and gas may be sent to gas
processing/storage 716, and liquid may be sent to liquid
processing/storage 718. Production facility 710 is able to produce
and/or store enhanced oil recovery formulation, which may be
produced and stored in production/storage 730.
[0067] In a first step, a first enhanced oil recovery formulation
is pumped down well 712, to portions 734 of formation 706. Enhanced
oil recovery formulation traverses formation 706 to aid in the
production of oil and/or gas from fractures, karsts, and/or vugs
707, and then the enhanced oil recovery formulation and oil and/or
gas may all be produced to well 732, to production facility 710.
Enhanced oil recovery formulation may then be recycled, for example
by re-injecting the formulation into well 712.
[0068] In some embodiments, in another step, a second enhanced oil
recovery formulation, which is denser than oil and/or gas in
formation 706 is injected at the bottom of well 712, near the
interface of formations 706 and 708. The enhanced oil recovery
formulation injection rate may be adjusted to be near the
imbibition rate of the formulation into the matrix surrounding the
fractures, karsts, and/or vugs 707. The formulation and oil and/or
gas are produced from a middle portion of well 712 in between the
first enhanced oil recovery formulation with a low density and the
second enhanced oil recovery formulation with a high density. Since
oil and/or gas is denser than the first enhanced oil recovery
formulation, the oil and/or gas sinks below the first enhanced oil
recovery formulation. In addition, since oil and/or gas is lighter
than the second enhanced oil recovery formulation, the oil and/or
gas floats above the second enhanced oil recovery formulation.
[0069] In some embodiments, a first enhanced oil recovery
formulation, which is less dense than oil and/or gas in formation
706 is injected at the top portion of well 712 in dome 714, near
the interface of formations 706 and 704. The enhanced oil recovery
formulation injection rate may be adjusted to be near the
imbibition rate of the formulation into the matrix surrounding the
fractures, karsts, and/or vugs 707. The formulation and oil and/or
gas are produced from a bottom of well 732, near the interface of
formations 706 and 708. Since oil and/or gas is less dense than
formulation, formulation causes the oil and/or gas to sink. Oil
and/or gas naturally sinks below formulation from upper elevation
near injection at well 712, to lower elevation production at well
732.
[0070] It will be appreciated by those of skill in the art that if
a gas is injected into well 712, it will quickly flow through the
fractures, karsts, and/or vugs 707, across formation 706 to well
732, and not interface with the oil and/or gas in the matrix. For
that reason, the gas is injected into well 712 in a foam to create
a pressure drop along the fracture to encourage more of the gas to
enter into the matrix.
[0071] In some embodiments, well 732 which is producing oil and/or
gas is representative of a well in well group 202, and well 712
which is being used to inject enhanced oil recovery formulation is
representative of a well in well group 204. In some embodiments,
well 732 which is producing oil and/or gas is representative of a
well in well group 204, and well 712 which is being used to inject
enhanced oil recovery formulation is representative of a well in
well group 202.
[0072] In some embodiments, oil and/or gas produced may be
transported to a refinery and/or a treatment facility. The oil
and/or gas may be processed to produced to produce commercial
products such as transportation fuels such as gasoline and diesel,
heating fuel, lubricants, chemicals, and/or polymers. Processing
may include distilling and/or fractionally distilling the oil
and/or gas to produce one or more distillate fractions. In some
embodiments, the oil and/or gas, and/or the one or more distillate
fractions may be subjected to a process of one or more of the
following: catalytic cracking, hydrocracking, hydrotreating,
coking, thermal cracking, distilling, reforming, polymerization,
isomerization, alkylation, blending, and dewaxing.
Illustrative Embodiments
[0073] In one embodiment of the invention, there is disclosed a
method for producing oil from an underground formation comprising
injecting an enhanced oil recovery formulation into a first well in
the formation, the enhanced oil recovery formulation comprising a
foam; floating the foam on top of the oil, in order to force the
oil towards a second well in the formation; and producing the oil
and/or gas from the second well. In some embodiments, the first
well further comprises a first array of wells, and the second well
further comprises a second array of wells, wherein a well in the
first array of wells is at a distance of 10 meters to 1 kilometer
from one or more adjacent wells in the second array of wells. In
some embodiments, the underground formation is beneath a body of
water. In some embodiments, the foam is injected into one or more
fractures in the formation. In some embodiments, the method also
includes injecting a second enhanced oil recovery formulation into
the formation, the second enhanced oil recovery formulation being
denser than the oil, further comprising floating the oil on the
second enhanced oil recovery formulation. In some embodiments, the
first array of wells comprises from 5 to 500 wells, and the second
array of wells comprises from 5 to 500 wells. In some embodiments,
the enhanced oil recovery formulation comprises gas and a
surfactant. In some embodiments, the enhanced oil recovery
formulation comprises a gas selected from nitrogen, carbon dioxide,
natural gas, and other hydrocarbon gases having from one to four
carbon atoms. In some embodiments, the second enhanced oil recovery
formulation comprises a carbon disulfide formulation. In some
embodiments, the underground formation comprises a oil having a
viscosity from 100 to 5,000,000 centipoise. In some embodiments,
the enhanced oil recovery formulation is less dense than the oil.
In some embodiments, the oil floats on the enhanced oil recovery
formulation.
[0074] Those of skill in the art will appreciate that many
modifications and variations are possible in terms of the disclosed
embodiments of the invention, configurations, materials and methods
without departing from their spirit and scope. Accordingly, the
scope of the claims appended hereafter and their functional
equivalents should not be limited by particular embodiments
described and illustrated herein, as these are merely exemplary in
nature.
* * * * *