US 4,228,853 A · Petroleum production method

Abstract

A method for electrical resistance heating of select portions of a natural underground reservoir, in a geologic formation, that contains both crude oil and water. Through selective resistance heating, oil viscosity is reduced in the select portion of the reservoir. Thus, portions which would not normally be contacted by injected fluids may be rendered susceptible to recovery by water flooding or other recovery process. Thermal expansion of heated oil also facilitates oil recovery. Resistance heating is accompanied by injection of low resistivity liquid that functions both as a conductor, through which current passes into the select portions, and as a medium for displacing oil to a production well. The low resistivity liquid also conveys convective heat, which contributes to viscosity reduction. Alternatively, the method of the invention can be used for altering the drainage pattern of a well.

Claims31

Dependent claims

A method for facilitating recovery of oil from a crude oil reservoir by selective electrical resistance heating of a portion of the reservoir which would normally be substantially bypassed by fluid injected into the formation in which the reservoir is located, the method comprising the steps of:

establishing a series electrical circuit for passing current through the formation along a directed path differing from the naturally predominant path of injected fluid flow, said naturally predominant path being substantially occupied by high resitivity fluid, said circuit comprising:
a source of alternating current electric power,
a first subterranean electrode electrically connected to one terminal of said source and located in or in proximity to a first well in said formation,
a second subterranean electrode electrically connected to the other terminal of said source and located in or in proximity to a second well in said formation, and
a portion of an oil reservoir in said formation that contains oil and water and is located between said electrodes substantially separate from a naturally predominant path for flow of injected fluids from an injection well through said formation but affords a current path of lesser electrical resistance between said electrodes than that along said naturally predominant path or any alternative path through the formation that is entirely outside said portion;
injecting a low resistivity liquid through an injection well into a region of said formation that forms a part of said circuit in series with said first electrode and said portion;
and
passing alternating current from said power source through said circuit so as to cause selective electrical resistance heating of said portion, whereby the resistance to the flow of oil contained in said portion is reduced and oil is swept out of said portion by said low resistivity liquid.

5 more elements

A method for recovering additional oil from a layered crude oil reservoir having layers of unequal permeabilities in a geologic formation that has been subjected to prior injection of a high resistivity fluid through an injection well for removal of oil from the reservoir to a recovery well where it is produced, the method comprising the steps of:

establishing a series electric circuit comprising:
a source of alternating current electric power,
a first subterranean electrode electrically connected to one terminal of said source and located in said formation in or in proximity to a first well in said formation,
a second subterranean electrode electrically connected to the other terminal of said source and located in said formation in or in proximity to a second well in said formation;
and
a relatively low permeability layer of a reservoir, located between said electrodes in said formation, that contains oil and salt water and has been substantially bypassed by the injection of said high resistivity fluid;
injecting a low resistivity liquid through an injection well into a region of said formation that forms a part of said circuit in series with said first electrode and said portion;
and
passing alternating current from said power source through said circuit so as to cause selective electrical resistance heating of said low permeability layer, whereby the resistance to the flow of oil contained in said layer is reduced and said oil is swept out of said layer by said low resistivity liquid.

6 more elements

A pattern flooding method for recovering oil from a crude oil reservoir in a geologic formation wherein oil is recovered from a portion of a reservoir that is substantially separate from the naturally predominant path for fluid flow between any injection well and a recovery well in the pattern so that said portion normally is substantially bypassed by injected fluid, the method comprising the steps of:

establishing a series electrical circuit comprising:
a source of alternating current electrical power,
a first subterranean electrode electrically connected to one terminal of said source and located in said formation in or in proximity to a first well in said formation,
a second subterranean electrode electrically connected to the other terminal of said source and located in said formation in or in proximity to a second well in said formation, and
a portion of said reservoir that contains oil and water and is in a region substantially separate from the naturally predominant path for flow of injected fluid from any injection well to any recovery well in said pattern;
injecting through an injection well into a region of said formation that forms a part of said circuit in series with said first electrode and portion a low resistivity liquid having a resistivity less than that of the connate water in said formation;
and
passing alternating current from said power source through said circuit so as to cause selective electrical resistance heating of said portion whereby the resistance to the flow of oil contained in said portion is reduced and oil is swept out of said portion by said low resistivity liquid.

5 more elements

A pattern flooding method for recovering oil from a crude oil reservoir in a geologic formation, wherein oil is recovered from a portion substantially separate from the naturally predominant path for flow of injected fluid from any injection well to any recovery well and thus normally bypassed by injected fluid, the method comprising the steps of:

providing a pattern comprising a plurality of injection wells disposed about a recovery well;
establishing between each injection well and each other injection well adjacent thereto in said pattern an electrical circuit comprising:
a source of alternating current electric power,
a first subterranean electrode electrically connected to one terminal of said source and located in said formation in or in proximity to a first injection well,
a second subterranean electrode electrically connected to the other terminal of said source and located in said formation in or in proximity to an injection well adjacent to said first injection well, whereby the electrical polarity of the electrode in proximity to each injection well in said pattern is opposite that of the electrode at each said adjacent injection well on either side thereof, and
a portion of the oil reservoir, located between said electrodes and said formation, that contains oil and water and is substantially separate from the naturally predominant path for flow of injected fluid between either of said injection wells and a recovery well so that said portion would be normally bypassed by injected liquid,
injecting low resistivity liquid through said injection wells into regions of said formation that form parts of said circuit in series with said first and second electrodes, respectively, and said portion;
and
passing alternating current from said power source through each circuit so as to cause selective electrical resistance heating of each said portion whereby the resistance to the flow of oil contained in each portion is reduced and oil is swept out of said portion by said low resistivity liquid.

6 more elements

A method for selectively heating a relatively oil-rich portion of a crude oil reservoir in a geologic formation so as to alter the drainage pattern relative to a well in said formation and facilitate recovery of oil therefrom, the method comprising the steps of:

injecting into a relatively oil-lean portion of said reservoir adjacent said rich portion a high resistivity fluid for increasing the electrical resistivity of said lean portion;
establishing a series electric circuit comprising:
a source of alternating current power,
a first subterranean electrode electrically connected to one terminal of said source and located in said formation in or in proximity to a first well in said formation,
a second subterranean electrode electrically connected to the other terminal of said source and located in said formation in or in proximity to a second well in said formation, and
said rich portion located between said electrodes;
injecting a low resistivity liquid through an injection well into a region of said formation that forms a part of said circuit in series with said first electrode and said rich portion;
and
passing alternating current from said power source through said circuit so as to cause selective electrical resistance heating of said rich portion, whereby the resistance to the flow of oil contained in said rich portion is reduced so that drainage of oil from said rich portion to a recovery well is promoted.

6 more elements

Dependencies are inferred from the claim text.

Petroleum production method

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Petroleum production method

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Abstract

Claims31