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Publication numberUS3428125 A
Publication typeGrant
Publication dateFeb 18, 1969
Filing dateJul 25, 1966
Priority dateJul 25, 1966
Publication numberUS 3428125 A, US 3428125A, US-A-3428125, US3428125 A, US3428125A
InventorsParker Harry W
Original AssigneePhillips Petroleum Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Hydro-electropyrolysis of oil shale in situ
US 3428125 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)

1 mu; r pw g xR 394289125 1969 I H. w. PARKER 3,428,125

HYDRO-ELECTROPYROLYSIS OF OIL SHALE IN SITU Filed July 25, 1966 CASING IN SHALE FRACTU RES 6 O O (TCYTG CASING BRINE IN FRACTURES lNVEA/TOR H.W. PARKER BRINE H2O A r TOR/V5 vs 7 United States Patent o 3,428,125 HYDRO-ELECTROPYROLYSIS OF OIL SHALE' IN SITU Harry W. Parker, Bartlesville, Okla., assignor to, Phillips' Petroleum Company, a corporation of Delaware Eiled July 25, 19 66, SenNo. 567,530 U.S. Cl. 163-248 7 Claims Int. Cl. E215 43/24, 43/26 ABSTRACT OF THE DISCLOSURE Hydrocarbons are recovered from an oil shale formation insitu by injecting an electrolyte into the formation.

through two?- or more wells and imposing a potential drop across the formation between the'wells to pass gelectrical current therethrough and heat the same, to a temperature sufiiciently {high to pyrolize the hydrocarbons therein, while maintaining sufiicient pressure on theforgnationto prevent vapibrization of the electrolyte. The wells. may be linked together through the formation byiracturing or directional drilling, or a combination of both.

In another. aspect, the invention relates to varying thepressure required to prevent vaporization of the electrolyte in inverserelation to the ratio of the weight of salt to the weight of water when an aqueous salt is used asthe electrolyte.

In another aspect, the invention relates tothe production of hydrocarbons and non-condensable gases from oil shale by injecting an aqueous electrolyte intothe formation through two or more wells, and impressing a voltage betweentwo of said wells to heat the formation, while maintaining sufficient pressure on said formation to prevent vap r'i'zation of said electrolyte, and' producing gas and/or!) :through one or more other wells. Alternatively, the prod can also be removed from the formation via the wells'iirjnpressed with the voltage.

In U.Sf Patent 3,137,347, pyrolysis of oil shale in situ by means of electrocarbonization was disclosed. The cost of electrical power was recognized to be a major item in the operation ofthe process, but no solution was advanced. It is an object of this invention to reduce the power needed to pyrolyze oil shale in situ. Another object of the invention is to produce hydrocarbons and noncondensable gases from oil shale at lower temperatures than were heretofore possible.

Other aspects, objects and the several advantages of the invention will be apparent to one skilled in the art upon studying the drawing, specification, and appended claimssodium sulfate, sodium carbonate, and so on. It will be apparent to one skilled in the art that the addition of various electrolytes to water is a variable which can be controlled. A high electrolyte content in the water would raise the boiling point of the Water and thus reduce the pressure necessary to pyrolyze the shale.

The technique of hydro-electropyrolysis canbe applied after electrocarbonization: has been started in the manner described in U.S. Patent 3,137,347 or hydro-electropyrolysis can be used from the beginning. In one specific embodiment, two wells aredrilled at a distance from one another in the oil shale formation, an electrolyte such as an aqueous salt is injecte'ti' therethrough, an electrical potential is impressed across the casings of saidlwells to heat the shale formation; andsufficient pressure: is maintained on the formationfto prevent vaporization of the electrolyte. The wells may be linked together by either fracturing or directional drilling, or by a combination of thetwo. By-the latter method, directional drilling need not be relied upon todirctly hit another well. Regardless of the method used to link the wells, the electrolyte is injected into the formation under sufficient pressure to fracture the shale between the wells, and the pfessure is maintainedso as to prevent vaporization of the electrolyte.

After the heating zone has been established in "the shale, it can be extended indefinitely by drilling additional wells into the shale, injecting electrolyte into the formation under sufficient pressure to fracture same, and applying electrical current to heat thefshale while maintaining a pressure sufficient to preventgvaporization of the electrolyte. Said additional wells canj be directionally drilled so that a greater spacing would result.

The hydrocarbons and fnon-condensable gases produced by the process of this invention can be recoveredZ-by drillingone or more producing wells between the Wells impressed with electrical current. These wells mus also be pressured to prevent vaptjrization of. the: electrolyte.

Referring now to the drawings: e

A multi-well system is iillustrated' in combination with means for practicing one embodiment of the invention.

Well bores 1 and 2 hold casings 3 and 4 through which a suitable electrolyte suchgas brine is delivered to formation 11 by means of purn 8. Pressure sufficient to fracture the formation is su. lied by pumps 8. A source of electrical current 6 is used to heat the formation, while pressure means 7 maintain sufficient pressure on the formation to prevent vaporization of the electrolyte. Oil and non-condensable gases can be recovered from formation 11 via production well 5 which is cased.

Anelectrical connection is made between the easing of the two wells 3 and 4 filth the electnical circuit being completed through the brine in the fractures connecting the two wells in the oil shale zone. The casing is cemented to the well bore face near the oil shale zone in a conventionalmanner. A high voltage AC. or DC. potential of 440 volts or higher applies potential between the two wells to heat the formation with sufiicient back pressure of up to 1530 p.s.i.g. maintained on the wells so that temperatures of between 500 F. and 600 F. are maintained in the brine in the fractures 9 and 10. In this manner, the formation between the two wells is heated and the shale pyrolyzed at moderate temperatures below 750 F. Heating in this manner is continued for several months prior to production of the produced oil through cased production well 5;. Production well 5 is produced by flowing or by. a pump not shown. Oil and gas can be produced during the heating period.

Brine which may be saturated can be injected into casings 3 and 4 during the heating process. It is preferred that a saturated solution of brine be used as this will allow better conduction of current and thus more heating of the formation. The following concentrations of brine in water for different salts can be used depending upon the temperature of the water.

Percent Sodium chloride 39 Calcium chloride 60 Potassiumchloride 50 Sodium sulfate 40 Sodium carbonate 40 The amount of salt which can bedissolved in the water is a function of the temperature of the solution, and the water can be heated prior to injection in order to as nearly as possible saturate the water withfthe particular salt being used. The invention is not limited; to the use of any particular salt, but sodium chloride 'is preferred since it is readily available in ground waters.

It will be apparent to one skilled in the art that it is possible to make fuel gas from the coke remaining on the shale after it has been retortedQhy injecting air and/or steam into the spent shale. Removal of coke by air and/or steam will also prevent current flow through the spent shale.

In the practice of the invention, low temperatures are maintained by introducing increments of electrolyte into the formation while maintaining s ufficient pressure to keep the temperature at the desiredfll evel. For example, to pyrolyze at 600 F., it is necessary to maintain a pressure of 1530 p.s.i.g. If the shale locally becomes hotter than 600 F., the water will boil and the steam will transfer heat to cooler portions of the formation.

In principle, the concept of the invention is to raise the temperature of the shale sufiiciently high to pyrolyze the hydrocarbons therein, while maintaining sufficient pressure on the formation to prevent vaporization of the electrolyte.

Reasonable modification and variation are possible within the spirit and scope of the invention, theessence of which is producing hydrocarbons and non-condensable gases from oil shale in situ by injecting an electrolyte into the shale and applying electrical current thereto while maintaining pressure sufficient to prevent vaporization of the electrolyte.

I claim:

1. A method for producing hydrocarbons from oil shale formations in situ penetrated by at least two wells which comprises fracturing said formation to increase the overall flow permeability between said wells through said foramtion, introducing an aqueous electrolyte into said foirnation to increase the electrical conductivity of said formation, imposing a potential drop across said formation to promote current flow therethrough and consequent heating thereof and maintaining jsuf ficient pressure on, said formation to retain an aqueous electrolyte coductiive phase'within said formation.

2. A "'method in accordance with claim 1 wherein said electrolyte is a mixture of water and an inorganic salt.

3. A" method according to claim 2 wherein said inorganic salt is an alkali metal salt.

4. A'method according to claim 1 wherein said electrolyte is injected into said oil shale using gas pressure to fracture said oil shale and to maintain pressure sufficient to, prevent vaporization of said electrolyte.

5. The method of claim 1 wherein the amount of said aqueous electrolyte injected is suflicient to produce a substantially continuous conductive path through said formationibetween said wells.

.6. The method of claim 1 wherein the said potential drop is suflicient to substantially elevate the temperature of said formation and increase the mobility of said hydrocarbons 7. The method of claim 6 wherein said temperature is elevated by an amount of up to about 600 F.

References Cited UNITED STATES PATENTS STEPHEN J. NOVOSAD, Primary Examiner.

' US. Cl. X.R.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US849524 *Jun 23, 1902Apr 9, 1907Delos R BakerProcess of extracting and recovering the volatilizable contents of sedimentary mineral strata.
US2795279 *Apr 17, 1952Jun 11, 1957Electrotherm Res CorpMethod of underground electrolinking and electrocarbonization of mineral fuels
US3106244 *Jun 20, 1960Oct 8, 1963Phillips Petroleum CoProcess for producing oil shale in situ by electrocarbonization
US3137347 *May 9, 1960Jun 16, 1964Phillips Petroleum CoIn situ electrolinking of oil shale
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3696866 *Jan 27, 1971Oct 10, 1972Us InteriorMethod for producing retorting channels in shale deposits
US3724543 *Mar 3, 1971Apr 3, 1973Gen ElectricElectro-thermal process for production of off shore oil through on shore walls
US3782465 *Nov 9, 1971Jan 1, 1974Electro PetroleumElectro-thermal process for promoting oil recovery
US4135579 *Sep 30, 1977Jan 23, 1979Raytheon CompanyIn situ processing of organic ore bodies
US4382469 *Mar 10, 1981May 10, 1983Electro-Petroleum, Inc.Method of in situ gasification
US4473114 *Sep 29, 1982Sep 25, 1984Electro-Petroleum, Inc.In situ method for yielding a gas from a subsurface formation of hydrocarbon material
US4545435 *Apr 29, 1983Oct 8, 1985Iit Research InstituteConduction heating of hydrocarbonaceous formations
US4645004 *Apr 25, 1984Feb 24, 1987Iit Research InstituteElectro-osmotic production of hydrocarbons utilizing conduction heating of hydrocarbonaceous formations
US5055180 *Jan 9, 1991Oct 8, 1991Electromagnetic Energy CorporationMethod and apparatus for recovering fractions from hydrocarbon materials, facilitating the removal and cleansing of hydrocarbon fluids, insulating storage vessels, and cleansing storage vessels and pipelines
US5907662 *Jan 30, 1997May 25, 1999Regents Of The University Of CaliforniaElectrode wells for powerline-frequency electrical heating of soils
US5950728 *Jul 24, 1997Sep 14, 1999Bingham; Clarke S.Method and apparatus for enhancing oil recovery
US6026902 *Dec 18, 1998Feb 22, 2000Bingham; Clarke S.Method and apparatus for enhancing oil recovery
US6199634Aug 27, 1998Mar 13, 2001Viatchelav Ivanovich SelyakovMethod and apparatus for controlling the permeability of mineral bearing earth formations
US6805194Oct 18, 2002Oct 19, 2004Scotoil Group PlcGas and oil production
US8261832 *Sep 11, 2012Shell Oil CompanyHeating subsurface formations with fluids
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US9127206Jun 19, 2014Sep 8, 2015Foret Plasma Labs, LlcPlasma whirl reactor apparatus and methods of use
US9156715Dec 23, 2013Oct 13, 2015Foret Plasma Labs, LlcApparatus for treating liquids with wave energy from an electrical arc
US20070102152 *Sep 20, 2006May 10, 2007Alphonsus ForgeronRecovery of hydrocarbons using electrical stimulation
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U.S. Classification166/248, 166/272.6, 166/275
International ClassificationE21B43/24, E21B43/16
Cooperative ClassificationE21B43/2401
European ClassificationE21B43/24B