Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3882941 A
Publication typeGrant
Publication dateMay 13, 1975
Filing dateDec 17, 1973
Priority dateDec 17, 1973
Publication numberUS 3882941 A, US 3882941A, US-A-3882941, US3882941 A, US3882941A
InventorsPelofsky Arnold H
Original AssigneeCities Service Res & Dev Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
In situ production of bitumen from oil shale
US 3882941 A
Abstract
Hydrocarbons are recovered from oil shale deposits by introducing hot fluids into the deposits through wells and then shutting in the wells to allow kerogen in the deposits to be converted to bitumen which is then recovered through the wells after an extended period of soaking.
Images(1)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

United States Patent [191 Pelofsky [451 May 13, 1975 1 IN SlTU PRODUCTION OF BITUMEN FROM OIL SHALE [75] Inventor: Arnold H. Pelofsky, East Brunswick,

[73] Assignee: Cities Service Research &

Development Co., Cranbury, NJ.

[22] Filed: Dec. 17, 1973 [21] Appl. No.: 425,449

[52] US. Cl 166/303; 166/263 [51] Int. Cl E211) 43/24 [58] Field of Search 166/302, 303, 272, 263

[56] References Cited UNlTED STATES PATENTS 11/1966 Thomas 166/303 X 5/1967 Strubhar 166/303 X 3,358,762 12/1967 Closmann 166/303 3,382,922 5/1968 Needham..... 166/303 X 3,480,082 11/1969 Gilliland 166/303 X 3,515,213 6/1970 Prats 166/303 X 3,550,685 12/1970 Parker 166/303 3,618,663 11/1971 Needham 166/303 X Primary ExaminerStephen J. Novosad Attorney, Agent, or Firm-Joshua J. Ward; George L. Rushton [57] ABSTRACT Hydrocarbons are recovered from oil shale deposits by introducing hot fluids into the deposits through wells and then shutting in the wells to allow kerogen in the deposits to be converted to bitumen which is then recovered through the wells after an extended period of soaking.

6 Claims, 2 Drawing Figures IN SITU PRODUCTION OF BITUMEN FROM OIL SHALE BACKGROUND OF THE INVENTION This invention relates to the recovery of bitumen from oil shale and more particularly to an in situ process for conversion of kerogen to bitumen and recovery of the resulting bitumen.

Oil shale deposits are found in many locations throughout the world and are a potential source of extremely large quantities of hydrocarbon products. Oil shale is generally a laminated, nonporous, impermeable, fine-grained dolomitic marlstone containing variable but relatively large amounts of organic matter known as kerogen. Kerogen is a high molecular weight substance largely insoluble in benzene and which is dispersed throughout an inorganic matric composed-principally of carbonates along with other minor constituents. The kerogen in oil shale is relatively rich in hydrogen and will yield a benzene soluble material (bitumen) on heating.

Many proposals have been made for recovering usuable hydrocarbons from oil shales, most of which involve the use of heat in one form or another to soften or liquefy the kerogen for conversion to bitumen or for further conversion to produce both liquid and gaseous products. The heat may be applied in situ or the shale may be mined by conventional mining methods with subsequent heating or retorting of the mined shale. In conventional in situ retorting, a heating agent is injected into one or more wells extending into the shale deposit and product is produced through the same or separate wells. It is also known to inject air into the formation to ignite the kerogen and form a combustion front which is then moved through the formation in a conventional manner to liquefy and partially gasify the kerogen and carry the liquid and gaseous product through the formation to wells from which it may be recovered. In situ processes frequently involve fracturing the shale deposit to facilitate contact between heating agents and kerogen.

In all of the previously known in situ processes for recovery of bitumen from shale deposits, thermal efficiency has been extremely low because, once formed from the kerogen, bitumen has been recovered at relatively high temperatures. Also a significant amount of the bitumen that has been formed migrates through the formation and is not recovered. It is therefore an object of the present invention to recover bitumen from shale deposits by means of a novel in situ recovery process which involves recovery of substantial quantities of bitumen with a high degree of thermal efficiency and to reduce the migration of the bitumen out of the formation.

SUMMARY OF THE INVENTION Hydrocarbon product is recovered from a subterranean deposit of oil-shale by introducing heat energy into the deposit through one or more wells extending into the deposit. Heat energy is introduced in quantities sufficient to heat the deposit in the vicinity of the wells to more than 50F (Fahrenheit Degrees) above its transition temperature (the temperature at which exfoliation of the shale structure commences).The wells are then shut in until the temperature in the vicinity of the wells drops to less than 50 above transition temperature, at which time the wells are again opened and bitumen is produced therefrom.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a vertical cross-sectional view illustrating use of the present invention in recovery of hydrocarbons from an oil shale deposit.

FIG. 2 is a horizontal cross-sectional view further illustrating use of the invention in recovering hydrocarbons from oil shale deposits.

DETAILED DESCRIPTION OF THE INVENTION those at which bitumen is normally recovered from such deposits while achieving at the same time recovcry of substantial quantities of the total possible recoverable hydrocarbons. As mentioned above, this is accomplished by introducing heat energy into the deposit through one or more wells extending into the deposit with the heat energy being introduced in quantities sufficient to heat the deposit in the vicinity of the wells to more than 50F above its transition temperature. The transition temperature is considered to be that temperature at which exfoliation (swelling) of the shale structure begins to take place. The wells are then shut in until the temperature of the deposit in the vicinity of the wells drops to less than 50F above the transition temperature of the deposit at which point the wells may be opened and bitumen produced therefromor additional heat energy may be introduced for conversion of additional kerogen to bitumen. If the bitumen is not removed, it will act as a solvent and tend to solubilize more of the kerogen.

The exfoliation temperature for a particular shale deposit varies depending on the amount of kerogen contained in the shale between about 600 and about 700F. with the lower transition temperatures occuring in connection with relatively richer shale deposits. When an oil shale deposit is heated to above its transition temperature in the absence of oxygen, exfoliation is accompanied by a marked increase in permeability. If the shale is allowed to remain above the transition temperature for a few hours, the permeability decreases again to the original value, usually essentially zero. If,'however, the shale deposit is maintained above its transition temperature for a substantial length of time, such as weeks or months, significant portions of the kerogen are converted to bitumen which has substantially lower viscosity than the kerogen and can flow freely through the inorganic matrix of the shale deposit. In accordance with this invention, the shale deposit is heated to more than 5OF and preferably at least about F above its transition temperature and then allowed to cool to less than 50F, preferably to about 25F or less above its transition temperature before recovery of any bitumen therefrom. This allows ample time for substantial quantities of kerogen to convert to bitumen and allows heat to be transferred to further portions of the formation to avoid loss of thermal efficiency in recovery of bitumen from the deposit. It also allows the bitumen to act as a solubilizing agent on the undissolved or unconverted kerogen.

Introduction of heat energy to a shale deposit in accordance with the invention can be by any suitable means with use of hot fluids at temperatures between about 700 and about 2,000F. being preferred. Preferred fluids include steam and hot water although other fluids not containing free oxygen, such as liquid or vaporous hydrocarbons, flue gas, etc. may be used.

Because of the extremely low permeability of oil shale deposits, it is usually not possible to inject hot fluids at normal injection rates without increasing pressure in the injection well to an undesirable degree before the desired rise in temperature has taken place in significant portions of the surrounding shale deposit. It is therefore preferred that the initial step of heating the deposit in the vicinity of the wellbores to more than 5OF- above its transition temperature be done in stages. In this preferred embodiment of the invention, hot fluid is injected through the wells until the pressure is raised to between about 200 and about 1,000 psi above normal formation pressure of the deposit. The wells are then shut in for a period of time necessary to allow the pressure to drop to less than about 50 psi above the formation pressure of the deposit. This frequently takes between about 2 weeks and about six months. Additional hot fluid is then injected until the pressure again rises more than 200 psi above formation pressure. Similar cycles of injection and shut in are continued until the temperature in the vicinity of the injection wells reaches the desired range of more than 50F above the transition temperature of the deposit. The injection wells'are then shut in until the temperature in the vicinityof the wells drops to less than 5OF above the transition temperature of the deposit at which time bitumen may be produced from the wells or, preferably, injection of hot fluids as described above is again resumed. By so resuming injection of hot fluids, the affected area of the shale deposit may be extended beyond that possible by merely raising the temperature in the immediate vicinity of the wells. This is possible because of the increased permeability of the formation in the vicinity of the wells due to conversion of kerogen to lower viscosity bitumen during the injection and shut in cycles mentioned above and also because the bitumen tends to so]- ubilize additional kerogen.

Once the deposit in the immediate vicinity of the injection wells has been heated to more than 50F above its transition temperature, it is preferred that the wells be shut in for between about 6 months and about 1 year to allow the temperature to drop to less than 50F and more preferably to less than 25F above transition temperature. Bitumen may then be produced from the wells or more preferably injection of hot fluids may be resumed to extend the affected area of the deposit before production of any bitumen therefrom. Such expansion of the effected area of the deposit preferably is carried out in the same manner as the original heating of the deposit described above, i.e., hot fluids are injected into the deposit until the well pressures rise to between about 200 and about 1,000 psi above normal formation pressures, the wells are shut in for between about 2 weeks and about 6 months to allow pressure to return to less than 50 psi above formation pressure and injection of hot fluids is then resumed on the same basis until temperatures in the previously unaffected portions of the shale deposit surrounding the wells have been raised to more than 50F. above their transition temperatures. The increase in temperature of previously unaffected shale deposit may in part. or in whole be achieved by indirect transfer of the heat from the injected hot fluids through previously formed bitumen.

It is preferred that the introduction of heat energy into the shale deposit as described above be'continued until the deposit has been heated to more thanv 5OF above its transition temperature throughout a sphere having a radius of at least about 50 feet from the injection point of each well through whichhot fluid has been injected. Each portion of the deposit so heated should then be allowed to soak with the wells shut in until the temperature again drops to less than 50F above the transition temperature (usually for a period of at least about 6 months) to allow time for conversion of kerogen to bitumen. For maximum efficiency of recovery, it is preferred that no bitumen be produced from the deposit until all of the above heating and soaking cycles have been completed at least once for each portion of the deposit contained within the spheres mentioned above.

ln practicing the invention, it is important to avoid fracturing the shale deposit since any fractures .formed beyond the area of the deposit in which kerogen is transformed to bitumen will result in excessive loss of bitumen into other portions of the deposit-or surrounding formations. For the same reason, it is not desirable to allow the portions of the deposit in which kerogen is converted to bitumen to extend to the boundaries of the shale deposit if the surrounding or underlying formations or overburden are permeable. For this reason, it is preferred that theinvention be practiced in shale deposits having a thickness of at least about 200 feet and that the periphery of each of the spheres of affected area in which kerogen is converted to bitumen remain a minimum of at least about 50 feet fromthe boundary of the deposit. Overlapping of affected spheres is, of course, permissible and frequently desirable to ensure maximum recovery of hydrocarbons but it is preferred that overlapping be kept to the minimum necessary to obtain desired recovery of hydrocarbons. Otherwise, excessive temperatures may build up in portions of the deposit thereby resulting in thermal inefficiency of undesirably long periods of time being required for heat to be transferred to other portions of the deposit. For this reason, it is preferred that the average temperature of affected portions of the shale deposits not rise above about 900F. and that, to the extent practical, temperatures above about 1200F. be avoided completely.

In practicing the invention, the temperature of the shale deposit may be determined by temperature sensing means introduced into the deposit such as through the wells used to inject hot fluids or by means such as infrared aerial photography which allows reasonably accurate determination of temperatures throughout the deposit. Most accurate temperature information is usually obtained by a combination of these or other temperature measuring means. g

If the invention is carried out using the preferred embodiments described above, it is normally feasible to convert at least about percent and; frequently at least about percent of the kerogen inthe af ected areas of the deposit intobitumen-and to recover at least about 65 percent of such bitumen from the deposit. Recovery initially is by merely opening the injection wells as described above but it should be understood that in addition, other conventional primary, secondary and even tertiary recovery processes may be used as desired to recover bitumen.

Referring to the drawings, FIG. 1 shows a well 12 extending from the surface of the earth 14 through overburden formation 16 into a shale oil deposit 18. An underlying formation 20 is also indicated. The well 12 may be suitably lined and equipped with tubing, etc. in a conventional manner. A conduit 22 communicates at one end thereof to the top of the well l2. The other end of conduit 22 may be connected to a source of hot injection fluids (not shown) or may be connected to means for recovering bitumen produced from the shale deposit 18. Means (not shown) are also provided for closing off the conduit 22 completely to shut in the well 12.

As an example of recovery of hydrocarbons from oil shale in accordance with a preferred embodiment of the invention, superheated steam at a temperature of about 1,000F. may be introduced through the conduit 22 and well 12 into the shale deposit 18. The shale deposit 18 for this example begins about 2,000 feet below the surface and has a thickness of 200 feet from top to bottom and a normal formation pressure of about 1,000 psi. Injection of steam at the rate of 4,000 pounds per hour through the well 12 for up to 8 hours will increase the well pressure to 2000 psi at which time the well is shut in for 4 weeks to allow the pressure to return to less than 50 psi above the formation pressure. Three subsequent similar cycles of injection and shutting in are required to raise the temperature of the shale deposit in the vicinity of the well (within a sphere 24 as represented in FIG. 1) to a temperature 100F. above the formation transition temperature of 562F. The well 12 is then shut in for 6 months during which time the temperature within the sphere 24 diminishes to 587F. (25 above formation transitions temperature). At this time at least about 20 percent of the kerogen contained within the sphere 24 has been converted to bitumen. A series of injections and shut ins similar to that described immediately above is then used to extend the affected area of the shale deposit to encompass all the material within a sphere 26 (FIG. 1). Also during this period of time more of the kerogen is converted to bitumen by the action of not only the heat energy but also the solubilizing effect of the bitumen itself until about 90% of the kerogen is converted. Another complete series of injections and shut ins as described above is used to extend the effected area of the shale deposit in which kerogen is converted to bitumen to encompass material within the sphere 28 as shown in FIG. 1. At this time (a total of years after the start of the injections) bitumen is produced from theshale deposit through the well 12. A total of 65 percent of the bitumen contained within the deposit is produced by primary recovery and an additional 25 percent is available for production by conventional secondary and tertiary methods.

To recover the maximum amount of hydrocarbons from a shale formation it is generally desirable to use more than one well as is depicted in FIG. 2 which shows an oil shale deposit 32 with a number of wells such as 34 and 40 completed within the shale deposit. By injecvert kerogen to bitumen throughout the maximum possible volume of the deposit and that none of the spheres reaches the boundary of the deposit. By keeping the spheres from reaching the boundary of the shale deposit and avoiding fracturing of the shale, it is possible to take advantage of the extremely low permeability of the natural shale deposit to prevent loss of bitumen be fore it can be produced from the deposit.

While the invention has been described above with respect to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit or scope of the invention.

What is claimed is:

l. A process for recovering hydrocarbon product from a subterranean deposit of oil shale which comprises the steps of:

a. introducing heat energy in the form of hot fluids not containing oxygen into said deposit through one or more wells extending into the deposit, said heat energy being introduced in quantities sufficient to heat the deposit in the vicinity of the wells to more than about 50F above its transition temperature and until the pressure at the bottom of the wells is from at least 200 to about 1,000 psi about the formation pressure of the deposit;

b. then shutting in said wells until the temperature in the vicinity of the wells drops to less than about 50F above the transition temperature of the deposit until the pressure at the bottom thereof drops to less than about 50 psi above formation pressure, with the shutting in period lasting from about two weeks to about 6 months;

c. repeating steps (a) and (b) for a period of from about I to about 10 years; and

d. producing bitumen through said wells.

2. The process of claim 1 in which steps (a) and (b) are repeated until the deposit has been heated to more than 50F above its transition temperature and then allowed to drop to less than 5OF above its transition temperature throughout a sphere having a radius of at least about 50 feet from the bottom of each of said wells.

3. The process of claim 2 in which at least about percent of the kerogen in the spheres is converted to bitumen before bitumen is produced through the wells.

4. The process of claim 2 in which the deposit of oil shale is at least about 200 feet thick, the radius of each of the spheres is between about 50 and about 500 feet and the periphery of each sphere is at least 50 feet from the boundary of the deposit.

5. The process of claim 1 in which heat energy is injected in the form of hot fluids at a temperature of bet-ween about 500and about 2,000F.

6. The process of claim 1 in which step (b) takes at least about 6 months.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3284281 *Aug 31, 1964Nov 8, 1966Phillips Petroleum CoProduction of oil from oil shale through fractures
US3322194 *Mar 25, 1965May 30, 1967Mobil Oil CorpIn-place retorting of oil shale
US3358762 *Dec 6, 1965Dec 19, 1967Shell Oil CoThermoaugmentation of oil-producing reservoirs
US3382922 *Aug 31, 1966May 14, 1968Phillips Petroleum CoProduction of oil shale by in situ pyrolysis
US3480082 *Sep 25, 1967Nov 25, 1969Continental Oil CoIn situ retorting of oil shale using co2 as heat carrier
US3515213 *Apr 19, 1967Jun 2, 1970Shell Oil CoShale oil recovery process using heated oil-miscible fluids
US3550685 *Dec 20, 1967Dec 29, 1970Phillips Petroleum CoShale oil production
US3618663 *May 1, 1969Nov 9, 1971Phillips Petroleum CoShale oil production
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4091869 *Sep 7, 1976May 30, 1978Exxon Production Research CompanyIn situ process for recovery of carbonaceous materials from subterranean deposits
US4105072 *Jan 27, 1977Aug 8, 1978Occidental Oil ShaleProcess for recovering carbonaceous values from post in situ oil shale retorting
US4160481 *Feb 7, 1977Jul 10, 1979The Hop CorporationMethod for recovering subsurface earth substances
US4257650 *Sep 7, 1978Mar 24, 1981Barber Heavy Oil Process, Inc.Method for recovering subsurface earth substances
US4263970 *Jul 31, 1978Apr 28, 1981Occidental Oil Shale, Inc.Introducing an oxidizing gas
US4667739 *Mar 10, 1986May 26, 1987Shell Oil CompanyThermal drainage process for recovering hot water-swollen oil from a thick tar sand
US4753293 *Jan 18, 1982Jun 28, 1988Trw Inc.In-situ condensation of hydrocarbon solvent vapors mixed with water vapor causing flow of oil
US5025863 *Jun 11, 1990Jun 25, 1991Marathon Oil CompanyEnhanced liquid hydrocarbon recovery process
US5036917 *Dec 6, 1989Aug 6, 1991Mobil Oil CorporationMethod for providing solids-free production from heavy oil reservoirs
US5036918 *Dec 6, 1989Aug 6, 1991Mobil Oil CorporationMethod for improving sustained solids-free production from heavy oil reservoirs
US6588503Apr 24, 2001Jul 8, 2003Shell Oil CompanyIn Situ thermal processing of a coal formation to control product composition
US6702016 *Apr 24, 2001Mar 9, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation with heat sources located at an edge of a formation layer
US6722436Jan 25, 2002Apr 20, 2004Precision Drilling Technology Services Group Inc.Apparatus and method for operating an internal combustion engine to reduce free oxygen contained within engine exhaust gas
US6725920 *Apr 24, 2001Apr 27, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation to convert a selected amount of total organic carbon into hydrocarbon products
US7441603Jul 30, 2004Oct 28, 2008Exxonmobil Upstream Research CompanyHydrocarbon recovery from impermeable oil shales
US7644769Oct 16, 2007Jan 12, 2010Osum Oil Sands Corp.Method of collecting hydrocarbons using a barrier tunnel
US7677673Mar 5, 2007Mar 16, 2010Hw Advanced Technologies, Inc.Stimulation and recovery of heavy hydrocarbon fluids
US7857056Oct 15, 2008Dec 28, 2010Exxonmobil Upstream Research CompanyHydrocarbon recovery from impermeable oil shales using sets of fluid-heated fractures
US7986869 *Apr 21, 2006Jul 26, 2011Shell Oil CompanyVarying properties along lengths of temperature limited heaters
US8082995Nov 14, 2008Dec 27, 2011Exxonmobil Upstream Research CompanyOptimization of untreated oil shale geometry to control subsidence
US8087460Mar 7, 2008Jan 3, 2012Exxonmobil Upstream Research CompanyGranular electrical connections for in situ formation heating
US8104537Dec 15, 2009Jan 31, 2012Exxonmobil Upstream Research CompanyMethod of developing subsurface freeze zone
US8122955Apr 18, 2008Feb 28, 2012Exxonmobil Upstream Research CompanyDownhole burners for in situ conversion of organic-rich rock formations
US8127865Apr 19, 2007Mar 6, 2012Osum Oil Sands Corp.Method of drilling from a shaft for underground recovery of hydrocarbons
US8146664May 21, 2008Apr 3, 2012Exxonmobil Upstream Research CompanyUtilization of low BTU gas generated during in situ heating of organic-rich rock
US8151877Apr 18, 2008Apr 10, 2012Exxonmobil Upstream Research CompanyDownhole burner wells for in situ conversion of organic-rich rock formations
US8151884Oct 10, 2007Apr 10, 2012Exxonmobil Upstream Research CompanyCombined development of oil shale by in situ heating with a deeper hydrocarbon resource
US8167960Oct 21, 2008May 1, 2012Osum Oil Sands Corp.Method of removing carbon dioxide emissions from in-situ recovery of bitumen and heavy oil
US8176982Feb 6, 2009May 15, 2012Osum Oil Sands Corp.Method of controlling a recovery and upgrading operation in a reservoir
US8209192May 20, 2009Jun 26, 2012Osum Oil Sands Corp.Method of managing carbon reduction for hydrocarbon producers
US8230929Mar 17, 2009Jul 31, 2012Exxonmobil Upstream Research CompanyMethods of producing hydrocarbons for substantially constant composition gas generation
US8287050Jul 17, 2006Oct 16, 2012Osum Oil Sands Corp.Method of increasing reservoir permeability
US8313152Nov 21, 2007Nov 20, 2012Osum Oil Sands Corp.Recovery of bitumen by hydraulic excavation
US8540020Apr 21, 2010Sep 24, 2013Exxonmobil Upstream Research CompanyConverting organic matter from a subterranean formation into producible hydrocarbons by controlling production operations based on availability of one or more production resources
US8596355Dec 10, 2010Dec 3, 2013Exxonmobil Upstream Research CompanyOptimized well spacing for in situ shale oil development
US8616279Jan 7, 2010Dec 31, 2013Exxonmobil Upstream Research CompanyWater treatment following shale oil production by in situ heating
US8616280Jun 17, 2011Dec 31, 2013Exxonmobil Upstream Research CompanyWellbore mechanical integrity for in situ pyrolysis
US8622127Jun 17, 2011Jan 7, 2014Exxonmobil Upstream Research CompanyOlefin reduction for in situ pyrolysis oil generation
US8622133Mar 7, 2008Jan 7, 2014Exxonmobil Upstream Research CompanyResistive heater for in situ formation heating
US8641150Dec 11, 2009Feb 4, 2014Exxonmobil Upstream Research CompanyIn situ co-development of oil shale with mineral recovery
US8701788Dec 22, 2011Apr 22, 2014Chevron U.S.A. Inc.Preconditioning a subsurface shale formation by removing extractible organics
US8839860Dec 22, 2011Sep 23, 2014Chevron U.S.A. Inc.In-situ Kerogen conversion and product isolation
WO2001081239A2 *Apr 24, 2001Nov 1, 2001Shell Oil CoIn situ recovery from a hydrocarbon containing formation
WO2003062619A1 *Jan 10, 2003Jul 31, 2003Prec Drilling Tech Serv GroupApparatus and method for operating an internal combustion engine to reduce free oxygen contained within engine exhaust gas
Classifications
U.S. Classification166/303, 166/263
International ClassificationE21B43/24, E21B43/18, E21B43/16
Cooperative ClassificationE21B43/18, E21B43/24
European ClassificationE21B43/18, E21B43/24