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 numberUS3221811 A
Publication typeGrant
Publication dateDec 7, 1965
Filing dateMar 11, 1963
Priority dateMar 11, 1963
Also published asDE1235240B
Publication numberUS 3221811 A, US 3221811A, US-A-3221811, US3221811 A, US3221811A
InventorsMichael Prats
Original AssigneeShell Oil Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Mobile in-situ heating of formations
US 3221811 A
Abstract  available in
Images(2)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

Dec. 7, 1965 M. PRATS 3, 81

MOBILE IN-SIIU HEATING 0F FORMATIONS Filed March 11, 1963 2 Sheets-Sheet 1 FLUID PRODUCTION FLUID PRODUCTION FUEL AIR INJECTION INJECTION FLUID PRODUCTION FIG. 3

INVENTORZ M. PRATS HIS AGENT Dec. 7, 1965 M. PRATS 3,221,811

MOBILE IN-SITU HEATING OF FORMATIONS Filed March 11, 1963 2 Sheets-Sheet 2 FUEL INJECTION AIR FUEL rum) INJECTION PRODUCTION 'NJECHON DRIVE FLUID l T INJECTION 1 7 -"\B r OIL SAND l 1:; l1 ZZZZ 7ZZZZ XZZ Z AV/flW/flfl U/ M;7 14 jt BARREN SAND '0 AIRFLOW 2.2/27 lfl comausnou ZONE t 9 INJECTED BARRIER INVENTOR:

M. PRATS End H M C HIS AGENT United States Patent 3,221,811 MOBILE IN-SITU HEATING 0F FORMATIONS Michael Trrats, Houston, Tera, assignor to Shell Gil Company, New York, N.Y., a corporation of Delaware Filed Mar. 11, 1963, Ser. No. 264,384 Claims. (Cl. 16611) This invention relates to the heating of hydrocarbon or oil-bearing formations and pertains more particularly to an in-situ method for thermally fluidizing minerals or hydrocarbons occurring in or near sub-surface formations in which combustion cannot be maintained by the injection of air alone. The present method is especially useful in producing material from formations containing hydrocarbons or other organic materials, such as coal, in quantities that are not suflicient for combustion to be maintained in the formation by the injection of air or another oxygen-containing fluid.

The present method is based on the steps of injecting a fuel-containing fluid at one location, injecting an oxygen-containing fluid at a different location, burning the mixture formed where the fluids meet within the formation, and producing the combustion products, and displaced fluids from a third location. By adjusting the injection rates, the zone of combustion can be maintained in or moved through selected regions within the formation.

Combustion within a formation requires the presence of a fuel and oxygen in critical proportions at a temperature above a critical minimum. Some formations in which combustion cannot be maintained by the injection of air contain combustible materials or contain substances which produce combustible materials when they are heated, but contain these substances in proportions such that the heat from burning the combustible materials is insuflicient, or is too rapidly lost, to maintain a temperature at which ignition occurs.

In oil production processes, especially in the secondary recovery of oil, it is sometimes desirable to move a combustion front through a substantially barren formation, that is, one which will not support combustion, in order to supply heat to an adjacent formation. Various patents disclose methods of supplying both air and fuel to maintain an in-situ combustion in such barren formations.

However, in each of the processes suggested in the patent literature, the fuel and air are injected through the same well, either concurrently as components of a single fluid stream, or sequentially as components of intermittently injected fluids. One drawback to such a procedure is that When combustible materials flowing from the same injection well reach their ignition temperature within a cavern or fissure near the injection well, a backflashing can occur. This may damage the well. Secondly, in the patented procedures the pattern of the burning zone is necessarily confined to the general shape of an arc of a circle around the injection well and the region through which the burning zone can be moved is necessarily a generally circular or spherical region of expansion around the injection well.

It is therefore a primary object of the present invention to provide a method of carrying out in-situ heating within a formation to thermally fluidize minerals or hydrocarbons occurring in a formation which does not contain enough fuel to support combustion.

A further object of the present invention is to provide a method of heating an underground formation by forming a combustion front therein at any desired point so as to heat a selected region of the formation.

Another object of the present invention is to provide a method of heating an underground formation by means of a combustion front formed therein and subsequently selectively moving the combustion front as desired within the formation to heat various regions of the formation so as to volatilize minerals contained within the formation or to volatilize or reduce the viscosity of hydrocarbon materials contained within the formation and move them to a production well.

Still another object of the present invention is to provide a method for producing minerals or hydrocarbons from an underground formation by selectively heating various regions of the formation one or more times by means of a moving combustion front which is moved either continuously or in a stepwise fashion through the formation.

These and other objects of the invention will be understood from the following description taken with reference to the drawing, wherein:

. FIGURES 1 through 4 are plan views of three wells with various flow patterns of injected materials being schematically shown extending between the wells; and,

FIGURE 5 is a diagrammatic view of a pair of wells taken in longitudinal cross-section with the air and fuel flow patterns being schematically shown between the wells.

In FIGURE 1 a planned view of the preferred arrangements of wells is shown for use in carrying out the method of the present invention. The method is started by injecting a fuel such as methane into the formation to be heated through well number 1 and producing the fluid at well number 3. The several lines forming flow patterns of fuel represent the injection of fuel at successive and increasing flow rates.

After a suitable pattern of flow of fuel from well 1 to well 3 has been established, air or an oxygen-containing fluid is injected through well 2 (FIGURE 2) either simultaneously with or subsequent to the formation temperature of well 2 being raised by means of a suitable down-hole heating device. Alternatively, at the time the air is injected into well 2 with the fuel being present in the adjacent formation, the mixture can be ignited by any suitable ignition procedure, e.g., by utilizing an ignition means which would be lowered into the well to the desired depth. The air injection rate is preferably kept small enough compared to the fuel injection rate so that the fluids-produced in well 3 do not constitute an explosive mixture. With a small air injection rate, the regions of contact of the fuel and air are at least partially within the zone of the formation heated by any down-hole heater used within well 2. Once ignition has been accomplished, the heater can be turned off and the heat of combustion used to maintain the temperature of the air and fuel above the ignition temperature. The hatched portion shown in FIGURE 2 represents schematically the combustion front surrounding well 2 and extending to well 3.

The location of the combustion front (hatched portion) within the formation can be readily changed by adjusting the air and fuel injection rates. Increasing the injection rate of the air relative to that of the fuel moves the combustion zone further away from well 2, both in the direction toward well 1 and in the direction normal to a line between wells 1 and 2. A reduction in the fuel injection rate into well 1 will cause the combustion zone to move still further from well 2. An increase in the fuel injection rate into well 1 would have the opposite effect. Simultaneous increase of injection rates of both the fuel into well 1 and the air into well 2 would cause a greater sideward movement of the combustion front, thus allowing the combustion front to sweep into greater areas of the formation under consideration.

An analysis of the produced gas from well 3 indicates whether combustion is occurring. In the event that combustion within the formation has stopped, the gaseous mixture in the formation can be re-ignited in the manner in which it was originally ignited. The location of the regions in which combustion is occurring within the formation can be determined by methods well-known to reservoir engineers, such as by calculating the flow paths of the injected gas. Combustion can be maintained within the formation while moving the combustion front from one region to another as long as the injection rates of the fuel and the air are not changed so rapidly that the mixing zone is moved into portions of the formation which have not been previously heated to ignition temperature by the combustion front.

As illustrated in FIGURE 4, the location of the burning region within the formation can be readily changed by producing the fluids from an additional well 4 for example. By producing from well 4 located to the left of well 1, the burning region (hatched zone) can be relocated in a manner shown. The combustion zone can be moved back and forth between the wells as many times as desired. The rate at which the combustion zone can be moved is materially greater than the rates of movement which are possible for combustion zones produced by burning in a matrix containing a static body of fuel.

While the method of the present invention has been described herein above as being carried out through three wells or conduits in communication between the surface and the underground formation to be heated, it is quite apparent that it is not essential that three sub-surface locations be employed, as shown in FIGURE 5. In the arrangement shown in FIGURE 5, the well 6 is provided with 2 conduits 7 and 8 through which fuel is injected, and oil or other fluid production is produced, respectively. The open lower ends of the two conduits 7 and 8 are isolated one from the other by means of a packer 9. Preferably prior to start of production the barren sand formation 10 has been fractured in a manner well-known to the art with a barrier 11 preferably of a heat-resistent material such as cement, being injected into the fracture so as to extend radially from the well 4. Alternately, the barrier of a sealing material could be injected without fracturing the formation. From the fuel flow lines drawn on FIGURE it will be seen that the injected barrier directs the fuel flow into the formation in a manner such as to cause it to sweep a considerable area prior to it being contacted by the flow of air from conduit 12 positioned in well 13. Thus a combustion front forms at 14 and may be moved up or down within the formation by varying the flow of the two injected fluids. In the arrangement shown in FIGURE 5, two of the three subsurface locations are provided in a single well.

The method in general comprises establishing fluid communication from points above the surface to a least three sub-surface locations, establishing fluid communication through the formation between the sub-surface locations, injecting a fuel-containing fluid into the formation around at least one of the sub-surface locations, injecting an oxygen-containing fluid into the formation around at least-one of the sub-surface locations, adjusting the relative rates of the injections so that the injected fluids meet within the formation and displace fluids into the vicinity of at least one of the sub-surface locations, igniting the mixture formed along the junction of the injected fluids, controlling the relative rates of injection so that the burning mixture extends along a path having a selected and movable portion within the formation, and withdrawing the fluids displaced in the vicinity of at least one of the sub-surface locations.

. The above-described formation heating method can be used in conjunction with an oil production operation be similarly used in conjunction with the production of any mineral matter capable of being thermally converted to a liquid or gaseous fluid, for example, viscous petroleum materials. In addition to hydrocarbons, various examples of volatilizable contents of sedimentary strata susceptible to the method of the present invention may be native metals such as mercury, bismuth, antimony, arsenic, zinc, etc., sulfur, both native and in composition, inpyrite, mispickel, galena, redruthite, argentite, blends, etc., chlorides of the metals and alkalis such as calomel, sylvite, chlorite, salmiac, etc., oxides of the metals, such as arsenolite, etc., sulfides of the metals, such as cinnabar, etc., inorganic acids in compositions, such as carbonic dioxide, etc., and any volatilizable minerals produced by the chemical action upon the constituents of the strata of mineralizing agents.

The process can be used either for heating or for simultaneously thermally fluidizing and fluid driving a material which is present in the formation in which in-situ combustion cannot be maintained by injecting air along.

In simultaneously thermally fluidizing, fluid driving, and producing a material, the location into which fluids are displaced is maintained at a pressure lower than the injection pressures of the fuel in the air, and the fluidized material is withdrawn along with the fluid combustion products and the fluids displaced from the formation.

The initial permeability of the formation in which the burning is to be conducted is not a limitation. The necessary fluid communication through the formation can be established by hydraulic fracturing, underground explosions, or the like. The fissures and caverns in locations in which .the fuel-containing and oxygen-containing fluids meet will become filled with explosive mixtures and detonations will occur. Such explosions will convert the nearby portions of the formation to highly porous fragmented portions and the region of this occurrence will be moved along with any movements of the junction of the fuel-containing and oxygen-containing fluids.

In an operation which a normally solid material is thermally liquified and the fluid driven into a production well, the liquified material, such as sulfur, must be pumped out or removed in a manner so as to maintain a relatively low pressure in the production well. The present method can be employed to roast an ore, to reduce the viscosity of a liquid or solid which cannot be fluid-driven at the applicable pressures, or to pyrolyze a material into fluid products.

I claim as my invention:

1. A method of heating extensive areas of an underground formation for the purpose of heating a material in an underground location, said method comprising the steps of (a) injecting fuel at one point into an underground formation which is deficient in combustible material in an amount suflicient to maintain an underground combustion,

(b) injecting an oxygen-containing fluid into said underground formation at a point spaced from said fuelinjection point but within contact range of said in jected fuel,

(c) igniting said mixture of fuel and oxygen-containing fluid at least at one point along the contact front in the formation between said injection points where the fuel and oxygen-containing fluid combine into a combustible mixture, thereby forming a combustion front which subsequently propagates along the entire contact front,

(d) discharging the products of said combustion from said formation at a point displaced from the points at which the fuel and the oxygen-containing fuel are separately injected,

(e) controlling the injection rates of said fuel and said oxygen-containing fluid to maintain the combustion front in a selected area of said formation being heated, nd

(f) slowly increasing the flow rate of one of said injected materials relative to the other to cause the combustion front to move from a portion of the formation closer to one injection point toward the other injection point.

2. The method of claim 1 including the step of slowly decreasing the flow rate of said one injected material to cause the combustion front to move in the opposite direction between said injection points.

3. The method of claim 1 wherein the injection of fuel and the injection of oxygen-containing fluid into the formation take place through separate wells at points spaced from each other and from a production well.

4. The method of claim 3 wherein the injection wells are both to one side of and substantially in line together with said production well.

5. The method of claim 1 wherein the steps of injecting fuel and of injecting oxygen-containing fluid take place through separate spaced apart injection wells while the products of combustion are first discharged through a production well to one side of the injection wells and including the steps of subsequently closing the production well and opening another production well through which the products may be discharged substantially on the op posite side of said injection wells.

References Cited by the Examiner UNITED STATES PATENTS CHARLES E. OCONNELL, Primary Examiner.

BENJAMIN HERSH, Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2880803 *Jan 16, 1958Apr 7, 1959Phillips Petroleum CoInitiating in situ combustion in a stratum
US2913050 *May 12, 1955Nov 17, 1959Phillips Petroleum CoPreventing explosions in bore holes during underground combustion operations for oil recovery
US2954218 *Dec 17, 1956Sep 27, 1960Continental Oil CoIn situ roasting and leaching of uranium ores
US3007521 *Oct 28, 1957Nov 7, 1961Phillips Petroleum CoRecovery of oil by in situ combustion
US3026937 *May 17, 1957Mar 27, 1962California Research CorpMethod of controlling an underground combustion zone
US3097690 *Dec 24, 1958Jul 16, 1963Gulf Research Development CoProcess for heating a subsurface formation
US3120264 *Jul 9, 1956Feb 4, 1964Texaco Development CorpRecovery of oil by in situ combustion
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3349846 *Jul 30, 1964Oct 31, 1967Phillips Petroleum CoProduction of heavy crude oil by heating
US3361201 *Sep 2, 1965Jan 2, 1968Pan American Petroleum CorpMethod for recovery of petroleum by fluid injection
US3422891 *Aug 15, 1966Jan 21, 1969Continental Oil CoRapid breakthrough in situ combustion process
US4440224 *Oct 20, 1978Apr 3, 1984Vesojuzny Nauchno-Issledovatelsky Institut Ispolzovania Gaza V Narodnom Khozyaistve I Podzemnogo Khranenia Nefti, Nefteproduktov I Szhizhennykh Gazov (Vniipromgaz)Method of underground fuel gasification
US4456065 *Aug 20, 1981Jun 26, 1984Elektra Energie A.G.Heavy oil recovering
US6688387Apr 24, 2001Feb 10, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation to produce a hydrocarbon condensate
US6698515Apr 24, 2001Mar 2, 2004Shell Oil CompanyIn situ thermal processing of a coal formation using a relatively slow heating rate
US6708758Apr 24, 2001Mar 23, 2004Shell Oil CompanyIn situ thermal processing of a coal formation leaving one or more selected unprocessed areas
US6712135Apr 24, 2001Mar 30, 2004Shell Oil CompanyIn situ thermal processing of a coal formation in reducing environment
US6712136Apr 24, 2001Mar 30, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation using a selected production well spacing
US6712137Apr 24, 2001Mar 30, 2004Shell Oil CompanyIn situ thermal processing of a coal formation to pyrolyze a selected percentage of hydrocarbon material
US6715547Apr 24, 2001Apr 6, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation to form a substantially uniform, high permeability formation
US6715549Apr 24, 2001Apr 6, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation with a selected atomic oxygen to carbon ratio
US6719047Apr 24, 2001Apr 13, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation in a hydrogen-rich environment
US6722429Apr 24, 2001Apr 20, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation leaving one or more selected unprocessed areas
US6722430Apr 24, 2001Apr 20, 2004Shell Oil CompanyIn situ thermal processing of a coal formation with a selected oxygen content and/or selected O/C ratio
US6722431Apr 24, 2001Apr 20, 2004Shell Oil CompanyIn situ thermal processing of hydrocarbons within a relatively permeable formation
US6725920Apr 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
US6725921Apr 24, 2001Apr 27, 2004Shell Oil CompanyIn situ thermal processing of a coal formation by controlling a pressure of the formation
US6725928Apr 24, 2001Apr 27, 2004Shell Oil CompanyIn situ thermal processing of a coal formation using a distributed combustor
US6729395Apr 24, 2001May 4, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation with a selected ratio of heat sources to production wells
US6729396Apr 24, 2001May 4, 2004Shell Oil CompanyIn situ thermal processing of a coal formation to produce hydrocarbons having a selected carbon number range
US6729397Apr 24, 2001May 4, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation with a selected vitrinite reflectance
US6729401Apr 24, 2001May 4, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation and ammonia production
US6732795Apr 24, 2001May 11, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation to pyrolyze a selected percentage of hydrocarbon material
US6732796Apr 24, 2001May 11, 2004Shell Oil CompanyIn situ production of synthesis gas from a hydrocarbon containing formation, the synthesis gas having a selected H2 to CO ratio
US6736215Apr 24, 2001May 18, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation, in situ production of synthesis gas, and carbon dioxide sequestration
US6739393Apr 24, 2001May 25, 2004Shell Oil CompanyIn situ thermal processing of a coal formation and tuning production
US6739394Apr 24, 2001May 25, 2004Shell Oil CompanyProduction of synthesis gas from a hydrocarbon containing formation
US6742587Apr 24, 2001Jun 1, 2004Shell Oil CompanyIn situ thermal processing of a coal formation to form a substantially uniform, relatively high permeable formation
US6742588Apr 24, 2001Jun 1, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation to produce formation fluids having a relatively low olefin content
US6742589Apr 24, 2001Jun 1, 2004Shell Oil CompanyIn situ thermal processing of a coal formation using repeating triangular patterns of heat sources
US6742593Apr 24, 2001Jun 1, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation using heat transfer from a heat transfer fluid to heat the formation
US6745831Apr 24, 2001Jun 8, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation by controlling a pressure of the formation
US6745832Apr 24, 2001Jun 8, 2004Shell Oil CompanySitu thermal processing of a hydrocarbon containing formation to control product composition
US6745837Apr 24, 2001Jun 8, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation using a controlled heating rate
US6749021Apr 24, 2001Jun 15, 2004Shell Oil CompanyIn situ thermal processing of a coal formation using a controlled heating rate
US6752210Apr 24, 2001Jun 22, 2004Shell Oil CompanyIn situ thermal processing of a coal formation using heat sources positioned within open wellbores
US6758268Apr 24, 2001Jul 6, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation using a relatively slow heating rate
US6761216Apr 24, 2001Jul 13, 2004Shell Oil CompanyIn situ thermal processing of a coal formation to produce hydrocarbon fluids and synthesis gas
US6763886Apr 24, 2001Jul 20, 2004Shell Oil CompanyIn situ thermal processing of a coal formation with carbon dioxide sequestration
US6769483Apr 24, 2001Aug 3, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation using conductor in conduit heat sources
US6782947Apr 24, 2002Aug 31, 2004Shell Oil CompanyIn situ thermal processing of a relatively impermeable formation to increase permeability of the formation
US6789625Apr 24, 2001Sep 14, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation using exposed metal heat sources
US6805195Apr 24, 2001Oct 19, 2004Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation to produce hydrocarbon fluids and synthesis gas
US6820688Apr 24, 2001Nov 23, 2004Shell Oil CompanyIn situ thermal processing of coal formation with a selected hydrogen content and/or selected H/C ratio
US6866097Apr 24, 2001Mar 15, 2005Shell Oil CompanyIn situ thermal processing of a coal formation to increase a permeability/porosity of the formation
US6877554Apr 24, 2001Apr 12, 2005Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation using pressure and/or temperature control
US6910536Apr 24, 2001Jun 28, 2005Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation using a natural distributed combustor
US6948563Apr 24, 2001Sep 27, 2005Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation with a selected hydrogen content
US6991031Apr 24, 2001Jan 31, 2006Shell Oil CompanyIn situ thermal processing of a coal formation to convert a selected total organic carbon content into hydrocarbon products
US6994168Apr 24, 2001Feb 7, 2006Scott Lee WellingtonIn situ thermal processing of a hydrocarbon containing formation with a selected hydrogen to carbon ratio
US7032660Apr 24, 2002Apr 25, 2006Shell Oil CompanyIn situ thermal processing and inhibiting migration of fluids into or out of an in situ oil shale formation
US7036583Sep 24, 2001May 2, 2006Shell Oil CompanyIn situ thermal processing of a hydrocarbon containing formation to increase a porosity of the formation
US7096941Apr 24, 2001Aug 29, 2006Shell Oil CompanyIn situ thermal processing of a coal formation with heat sources located at an edge of a coal layer
US8608249Apr 26, 2010Dec 17, 2013Shell Oil CompanyIn situ thermal processing of an oil shale formation
EP0030430A1 *Nov 27, 1980Jun 17, 1981The University Of Newcastle Research Associates LimitedUnderground gasification of coal
Classifications
U.S. Classification166/245, 166/260
International ClassificationE21B43/16, E21B43/243, E21B43/247, E21B43/24
Cooperative ClassificationE21B43/247, E21B43/24, E21B43/243
European ClassificationE21B43/243, E21B43/247, E21B43/24