Abstract: Rubblized oil shale beds to be processed by the modified in situ retorting technique are U-shaped so that the inlet end and outlet end of the bed communicate with a common channel.

Abstract: The method of the present invention involves a two-phase process for in-situ retorting and recovery of carbonaceous material contained within typical subterranean tar sand formations, and includes formation of conventional arrays of in-seam ducts, and positioning heating devices to heat a section of the formation over a large extent thereof. The operation of the heating devices in the first phase is controlled to provide heat into the formation without burning of the carbonaceous material therein, resulting in development of a quasi-stable zone of pyrolysis about the heating duct, to thermally crack the carbonaceous material producing various organic liquid oil fractions and derived condensible vapors and non-condensible gases. The products produced thereby are then withdrawn through a suitable array of collection wells.

Abstract: Low heating value gases are combusted substoichiometrically in two combustion zones in series in contact with two different supported platinum catalysts in which the concentration of platinum in the catalyst in the first zone is higher than the concentration of platinum in the second catalyst. The combusted gas of reduced carbon monoxide can be directly vented to the atmosphere after energy has been extruded from it for a useful purpose.

Abstract: The combustible component of a gas stream of low heating value is combusted using less than a stoichiometric amount of oxygen with minor production of carbon monoxide due to the use of an oxygenation catalyst comprising at least three metals in a perovskite-type crystal structure. This combusted gas can be directly vented to the atmosphere after energy has been extracted from it for a useful purpose.

Abstract: A method of gasification of coal in deep, thin seams by using controlled bending subsidence to confine gas flow to a region close to the unconsumed coal face. The injection point is moved sequentially around the perimeter of a coal removal area from a production well to sweep out the area to cause the controlled bending subsidence. The injection holes are drilled vertically into the coal seam through the overburden or horizontally into the seam from an exposed coal face. The method is particularly applicable to deep, thin seams found in the eastern United States and at abandoned strip mines where thin seams were surface mined into a hillside or down a modest dip until the overburden became too thick for further mining.

Abstract: An integrated in situ combustion process for recovering subterranean liquid and solid carbonaceous deposits in which the resulting flue gas of low heating value is combusted at substoichiometric conditions over two different oxidation catalysts in two combustion zones in series and is expanded in a gas turbine which drives the air compressor for injecting the combustion air into the underground carbonaceous deposit. One of the oxidation catalysts comprising platinum and at least one metal cocatalyst selected from Groups IIA and VIIB, Group VIII up through atomic No. 45, the lanthanides, chromium, zinc, silver, tin and antimony is provided to reduce the carbon monoxide in the combusted flue gas.

Abstract: An integrated in situ combustion process for producing subterranean carbonaceous deposits in which the resulting flue gas of low heating value is combusted over an oxidation catalyst at substoichiometric conditions and is expanded in a gas turbine which drives the air compressor for injecting the combustion air into the underground carbonaceous deposit. An oxidation catalyst is provided for reducing carbon monoxide in the combusted flue gas comprising platinum and palladium.

Abstract: A process for recovering hydrocarbons from a subterranean formation in which in situ combustion is first initiated in the formation by injection of air, for example, through an injection well, the injection of air is terminated, carbon dioxide or nitrogen is injected into the formation via the injection well to displace unconsumed air and in a final step a mixture of carbon monoxide and hydrogen is injected into the formation where reaction of the carbon monoxide with steam generated from the formation water forms additional hydrogen and carbon dioxide and finally hydrocarbons are recovered via a production well.Optionally, after injection of the mixture of carbon monoxide and hydrogen into the formation has been terminated the heat stored in the formation may be recovered by injecting water as a drive fluid into the formation.

Abstract: A process for recovering a viscous, combustible material, for example tar from a tar sand or oil and bitumen from heavy oil, from a sub-surface deposit of the material. The process comprises forming a substantially vertical main bore into the deposit and igniting the deposit adjacent the base of the bore. Such ignition may be carried out by any means, for example by burning a fuel, by an explosion or by a laser beam. Generally the ignition is assisted until such time as the material in the deposit is ignited. A supply of air is arranged to the ignition site so that a self-sustaining combustion takes place in the bore once the ignition is properly established. This combustion is supported by a natural draft generated by the combustion. The gaseous products of the combustion can leave the bore and the heat of the combustion and of the gaseous products of combustion as they leave the bore liquefy the material in the deposit.

Abstract: A secondary combustion zone is established and its location controlled in a fragmented mass of particles containing oil shale in an in situ oil shale retort.A processing zone including a primary combustion zone is established in the retort by igniting a portion of the mass of particles. An oxygen supplying gas is introduced into the retort to advance the processing zone through the fragmented mass. If the primary combustion zone is not substantially planar or has not progressed uniformly, a secondary combustion zone is established upstream of the primary combustion zone by introducing into the retort a retort inlet mixture comprising fuel and at least sufficient oxygen for combustion of the fuel at a temperature no greater than the primary combustion zone temperature.The secondary combustion zone is caused to move upstream from its initial location in the in situ oil shale retort by reducing the ignition temperature of the retort inlet mixture.

Abstract: Gas is produced and extracted from a coal deposit by drilling a row of supply wells in the deposit for receiving air or another combustion supporting gas, cutting horizontal inclined supply passages along the bottom of the deposit extending from the bottom end of the supply wells to a channel at the other end of the deposit perpendicular to and interconnecting the supply passages, igniting the coal face in the channel to create a combustion zone, maintaining combustion by continuously supplying air to the combustion zone via the supply wells and supply passages, and continuously removing gases produced by combustion via a central discharge passage extending along the deposit parallel to the supply passages and production wells drilled from the surface to the discharge passage in a row perpendicular to the row of supply wells.

Abstract: Crude shale oil produced by in situ retorting of oil shale can contain from about 1 to 2% sulfur by weight, the sulfur being distributed widely through the lower and higher boiling fractions of the shale oil. Substantially non-condensible sulfur containing gas such as hydrogen sulfide is evolved from such crude shale oil by maintaining such shale oil at an elevated temperature in the substantial absence of added reagent, with the maximum temperature below thermal decomposition temperatures of such shale oil for sufficient time to lower the sulfur content of the shale oil.

Abstract: When processing a fragmented permeable mass of particles containing oil shale for recovering liquid and gaseous values, a portion of the oil shale is thermally metamorphosed. However, a zone of non-thermally metamorphosed particles can be left in the fragmented mass after completion of processing. To inhibit leaching by water of water-soluble constituents of such non-thermally metamorphosed particles, a heating fluid, such as a mixture of fuel and an oxygen-containing gas, is introduced to the fragmented mass containing non-thermally metamorphosed particles for heating at least a portion of the non-metamorphosed particles to a sufficiently high temperature for forming water-insoluble metamorphic minerals at at least the surfaces of such particles.

Abstract: An integrated in situ combustion process for producing subterranean carbonaceous deposits in which the resulting flue gas of low heating value is combusted over an oxidation catalyst at substoichiometric conditions and is expanded in a gas turbine which drives the air compressor for injecting the combustion air into the underground carbonaceous deposit. An oxidation catalyst is provided for reducing carbon monoxide in the combusted flue gas comprising platinum and at least one metal cocatalyst selected from Groups IA, II, III, VIIB and VIII up through atomic No. 45, the lanthanides, chromium, silver, tin and antimony.

Abstract: A process for recovering hydrocarbons from a subterranean formation in which in situ combustion is first initiated in the formation by injection of air, for example, through an injection well, the injection of air is terminated, carbon dioxide or nitrogen is injected into the formation via the injection well to displace unconsumed air and in a final step a mixture of carbon monoxide and hydrogen is injected into the formation where reaction of the carbon monoxide with steam generated from the formation water forms additional hydrogen and carbon dioxide and finally hydrocarbons are recovered via a production well.Optionally, after injection of the mixture of carbon monoxide and hydrogen into the formation has been terminated the heat stored in the formation may be recovered by injecting water as a drive fluid into the formation.

Abstract: A crude shale oil is produced by in situ retorting of oil shale in a fragmented permeable mass of formation particles containing oil shale in an in situ oil shale retort in a subterranean formation containing oil shale. A combustion zone is advanced through the fragmented mass by introducing an oxygen containing gas to the mass on the trailing side of the combustion zone and withdrawing an off gas from the fragmented mass on the advancing side of the combustion zone. Gas flow advances the combustion zone through the fragmented mass and transfers heat of combustion to a retorting zone on the advancing side of the combustion zone. Kerogen in oil shale in the retorting zone is decomposed to produce gaseous and liquid products including crude shale oil. Crude shale oil produced by such a process and having characteristics described herein is withdrawn from the fragmented mass on the advancing side of the retorting zone.

Abstract: A technique is described for breaking the very strong emulsion of shale oil and water produced by an in situ oil shale retorting process so that separate shale oil and water phases can be recovered. The emulsion is broken by maintaining a volume of such emulsion at a bulk temperature of at least about 120.degree. F., and momentarily heating portions of emulsion to a temperature substantially higher than the bulk temperature of the emulsion. Preferably the emulsion of shale oil and water is held at a bulk temperature in the range of from about 120.degree. to 190.degree. F. in contact with heating means maintained in the range of from about 170.degree. F. to about 240.degree. F. Momentary localized heating of emulsion to a temperature substantially higher than the bulk temperature of the emulsion accelerates the breaking of the emulsion.

Abstract: Disclosed is a process for the in situ retorting of oil shale and energy recovery from generated off gases. An underground retort containing rubblized oil shale is subjected to retorting, thereby forming shale oil and off gases. The off gases are purified and burned in a gas turbine. Commonly this process comprises forming a subterranean in situ retort containing rubblized oil shale having a void space of about 5 to about 40 percent; passing a retorting gas through the in situ retort to effectively retort the oil shale and produce a mixture of shale oil and off gases; subjecting the mixture of shale oil and off gases to a preliminary separation to remove gross quantities of shale oil from the off gases; passing a portion of the off gases to a purification zone so as to remove off gas impurities which would be detrimental to the environment or the operation of downstream equipment; and passing a portion of the purified off gases to a gas turbine where said off gases are burned and power is generated.

Abstract: A process incorporating integrated units and combined cycle energy production is provided for the recovery and upgrading of oil containing deposits which are not readily amenable to recovery and upgrading, to produce therefrom a light oil and elemental sulphur. Residual hydrocarbons generated in the process are gasified to produce hot gases which are used as a source of energy for process use, including electric power. The electric power is utilized to electrolyze water and produce hydrogen for use in upgrading and oxygen for use in gasification. The integration of gasification of residual hydrocarbons to produce, inter alia, electric power with the electrolysis of water to produce hydrogen for upgrading, and efficient use, distribution and recovery of energy in combined energy cycles provides an economical and essentially energy sufficient process with the flexibility to be adapted for the recovery and upgrading of various low yield oil deposits.

Abstract: The concentration of hydrocarbons, hydrogen, and carbon monoxide in a gas is reduced by combining these constituents in the gas with oxygen in the presence of a fragmented permeable mass of particles containing oil shale treated to remove organic materials.

Abstract: The hydrocarbon, hydrogen and carbon monoxide concentration of a gas is reduced by reacting these constituents in the gas with oxygen in the presence of a fragmented permeable mass of combusted oil shale.

Abstract: Combustion air injection well completion comprising an outer casing having a reduced diameter lower portion and a small diameter liner casing which is run inside the outer casing and screwed into the upper end of the small diameter portion of the outer casing. The resulting completion provides an annular conduit through which cooling or divertent fluid may be injected into formations while combustion air is simultaneously pumped through the inner casing and into formations through perforations in the small diameter portion of the outer casing.

Abstract: A method for initiating an in situ combustion operation for heating a well to recover petroleum from a subterranean reservoir in the well comprises lowering an elongated combustion chamber suspended from a hollow electrical cable with an air supply tube therearound which supplies electricity, fuel gas, and air to the combustion chamber, mixing an air-fuel mixture in the combustion chamber, and igniting the air-fuel mixture with an ignitor responsive to the thermocouple detecting burning in the combustion chamber for providing an automatic, reliable, and flame-out proof method for initiating heat deep in the well.

Abstract: The present invention is directed to an in situ coal gasification process wherein the combustion zone within the underground coal bed is fed with air at increasing pressure to increase pressure and temperature in the combustion zone for forcing product gases and water naturally present in the coal bed into the coal bed surrounding the combustion zone. No outflow of combustion products occurs during the build-up of pressure and temperature in the combustion zone. After the coal bed reaches a temperature of about 2000.degree. F and a pressure in the range of about 100-200 psi above pore pressure the airflow is terminated and the outflow of the combustion products from the combustion zone is initiated. The CO.sub.2 containing gaseous products and the water bleed back into the combustion zone to react endothermically with the hot carbon of the combustion zone to produce a burnable gas with a relatively high hydrogen and carbon monoxide content.

Abstract: The electric induction heating in situ of a selected portion of an underground coal deposit, for the purpose of facilitating extraction of gases, liquids, solids and energy from the deposit. The heating is conveniently effected by passing a time-varying electrical current through a conductor encompassing the selected portion. The conductive path is preferably a toroid, quasi-toroid, helix, or simulated toroid, quasi-toroid or helix, created by a drilling and passing one or more conductors through the drill holes.

Abstract: An underground carbonaceous deposit containing other mineral values is burned in situ. The underground hot zone is cooled down to temperature below the boiling point of a leaching solution. The leaching solution is percolated through the residial ash, with the pregnant solution recovered for separation of the mineral values in surface facilities.

Abstract: A technique is described for breaking the very strong emulsion of shale oil and water produced by an in situ oil shale retorting process so that separate shale oil and water phases can be recovered. The emulsion is broken by heating it to a temperature of at least about 120.degree. F. and holding at a temperature in the range of from about 120.degree. to 180.degree. F. for about one day. Preferably the shale oil and water are held in the range of from about 130.degree. to 150.degree. F. for about one day and the phases separated by gravity. Heat for the process can be obtained by injecting water into a spent in situ oil shale retort for generating steam and transferring heat from the steam to the emulsion.

Abstract: The present invention relates to the production of relatively high Btu gas by the in situ combustion of subterranean coal. The coal bed is penetrated with a horizontally-extending borehole and combustion is initiated in the coal bed contiguous to the borehole. The absolute pressure within the resulting combustion zone is then regulated at a desired value near the pore pressure within the coal bed so that selected quantities of water naturally present in the coal will flow into the combustion zone to effect a hydrogen and carbon monoxide-producing steam-carbon reaction with the hot carbon in the combustion zone for increasing the calorific value of the product gas.

Abstract: Sulfur dioxide is removed from a process gas by passing the process gas through a fragmented permeable mass of particles containing treated oil shale and including alkaline earth oxides. Water in the fragmented mass combines with alkaline earth oxides in the fragmented mass and sulfur dioxide in the process gas with resultant removal of sulfur dioxide from the process gas.

Abstract: A method for recovery of heat generated by the combustion of coal in situ within coal seams in the earth. Three embodiments are described: one, in which the coal seam crops out and into which can be drilled and inserted a pipe, through the coal seam, to a central point, where it is joined with a vertical pipe drilled from the surface. Water is supplied to the pipe at the point of outcrop. Fires are started within the coal seam and supplied with air from the surface by means of drilled boreholes. The heat of combustion converts the water in the pipe to steam which travels up the vertical pipe and is used to drive a turbine generator system. A second embodiment is used where there is an overlying aquifer above the coal seam. Fires are started by means of air supplied through boreholes leading from the surface into the coal seam. The heat of combustion converts the water in the aquifer to steam, which then is circulated out of the aquifer and up to the surface where it drives a turbine generator system.

Abstract: A method of producing combustible gases, synthetic crude oils, coal chemicals and heat from coal in situ utilizes the combined teachings of in situ gasification, liquefaction and pyrolysis.

Abstract: A method of producing viscous materials from subterranean formation comprises a plurality of steps. At least two wells are drilled and completed into the subterranean formation that contains the viscous material. At least one of the wells is completed as an injection well and one of the wells is completed as a production well. A plurality of electrode wells are drilled into the subterranean formation with the plurality of electrode wells being generally arranged in a pattern to define at least one path between the production well and the injection well with the length of the path being substantially greater than the distance between the production well and the injection well. The electrode wells are spaced apart along the path at distances that are substantially less than the distance between the production well and the injection well.

Abstract: To control the process of underground gasification of a coal bed with due provisions for the natural geological and mining conditions, in the disclosed method the rate of gassing-out the coal bed is selected from the following expression: ##EQU1## WHERE W is the amount of water flowing into the gasification zone, m.sup.3 /hour;I is the amount of coal gassed out per unit of time, tons/hour (the intensity of the process);Q.sub.h.sup.r is the combustion heat of the gas, kcal/m.sup.3 ;v.sup.r is the yield of gas from 1.0 kg of coal, m.sup.3 ;Q.sub.h.sup.y is the lowest combustion heat of coal, kcal/kg;m is the thickness of the coal bed, in meters.

Abstract: A method and apparatus for the removal and recovery of volatile or evaporable substances from materials containing them. In other embodiments, the invention is readily applicable for the simultaneous incineration and concentration of such materials, particularly spent water-diluted effluents from industries and municipalities as well as for the generation of electric power from various thermal fuels, particularly power gas produced from coal or oil. In further embodiments, the reclamation of oil, from oil sands and shales, is effected as well as the cyclic pulping of cellulosic materials with cyclic recovery of heat and chemicals.

Abstract: A method for heating a well or for initiating an in situ combustion operation to recover petroleum from a well in a subterranean reservoir, a method for assembling an ignition system for the in situ combustion, and an ignition system comprises an elongated combustion chamber suspended from a hollow electrical cable which supplies both electrical means and fuel gas to the chamber. Air inlet ducts in the walls of the combustion chamber receive air from the annular space between the hollow cable and the wellbore tubing. An electrical ignitor is temporarily energized to ignite the fuel-air mixture in the air inlet cylinder. An adjacent thermocouple is responsive to a flameout for re-energizing an ignitor manually such that burner operation is interrupted only momentarily .

Abstract: The present invention is directed to a method of in situ coal gasification for providing the product gas with an enriched concentration of carbon monoxide. The method is practiced by establishing a pair of combustion zones in spaced-apart boreholes within a subterranean coal bed and then cyclically terminating the combustion in the first of the two zones to establish a forward burn in the coal bed so that while an exothermic reaction is occurring in the second combustion zone to provide CO.sub.2 -laden product gas, an endothermic CO-forming reaction is occurring in the first combustion zone between the CO.sub.2 -laden gas percolating thereinto and the hot carbon in the wall defining the first combustion zone to increase the concentration of CO in the product gas. When the endothermic reaction slows to a selected activity the roles of the combustion zones are reversed by re-establishing an exothermic combustion reaction in the first zone and terminating the combustion in the second zone.

Abstract: An apparatus and method of burning fossile fuels, such as coal, in their places of natural deposit, for producing energy which may be utilized for various purposes, such as, for driving an electric generator.

Abstract: A method of extracting hydrocarbons, energy and other products in situ from an underground coal deposit. A selected part of the coal deposit is heated by electrical induction to temperatures high enough to effect the destructive distillation of coal. The gases and liquids so produced are collected. Next, air or oxygen is injected into the remaining deposit which consists primarily of coke in order to burn it in place. The hot combustion gases thereby yielded are led to the surface of the deposit to generate energy. Lastly, the heat remaining underground after the coke has been burned is extracted by injecting water or steam into the deposit. The resulting steam is conducted to the surface to drive a steam turbine. The electrical induction heating is conveniently effected by passing a selected time varying current through a conductive path encompassing that part of the coal deposit to be heated.

Abstract: A method of mine-less connection of wells for underground gasification by the filtrational fire connecting technique is intended primarily for forming a single unitary gasification channel for underground gasification of coal, oil shale and oil-bearing beds. In the disclosed method of connecting wells or boreholes drilled for underground gasification, the coal bed is ignited in one of the wells situated in the direction of formation of the unitary gasification channel. After a center of combustion has been set in this well, an air blast is directed at a permanent flow rate into the well with which the connection is to be effected. The pressure of the air blast charged into the well is measured, and when the pressure drops considerably, an air blast is charged for connection purposes into the next successive well in the direction of formation of the gasification channel.

Abstract: A technique is described for reducing the content of oil and water in the flue gas recovered from the bottom of an underground in situ oil shale retort. In such a retort air is passed downwardly to sustain a combustion zone for retorting oil which is recovered at the bottom. Flue gas recovered from the bottom of the retort contains water vapor and oil and water aerosols. These are removed from the flue gas by passing it a substantial distance upwardly through cool overburden so that the flue gas is cooled below its dew point so that water condenses in the vertical conduit and aerosols are dropped out on the walls. The oil and water are recovered at the bottom of the conduit and stored in an underground sump.

Abstract: Disclosed is a method for recovering low gravity, viscous petroleum including bitumen from a tar sand deposit by injecting unheated air followed by a soak period so that the viscous petroleum is conditioned by contact with the unheated air, followed by injection air or a mixture of heated air and steam to accomplish in situ combustion or low temperature oxidation within the viscous petroleum formation. The temperature of the unheated air injected in the first phase is less than 250.degree. F and preferably less than 150.degree. F, so as to avoid a combustion reaction between the air and the petroleum in the formation. The preliminary treatment with unheated air results in eliminating or decreasing the tendency for spontaneous ignition to occur at random sites in the formation, and produces more uniform combustion and propagation of the combustion front through the formation, and results in increased oil recovery from the formation.

Abstract: A method of processing recently bored channels when putting into operation an underground gas generator (underground gasifier), consisting, on the one hand, in forced air blowing and, on the other hand, in taking away hot gases, is characterized by determining the magnitude of the hydrostatic pressure by measuring the hydrostatic column of underground waters in a vertical direction from the point at which air is forced into the well to the level of the underground waters, and adjusting the outlet section of the gas discharging wells. This permits maintaining in the boring channel a pressure at a level which is not less than that produced by the hydrostatic column to preclude an inflow of underground waters to the channel being processed. The temperature in the channel is raised at a rate from about 80.degree. C to about 100.degree. C per hour up to at least 500.degree. C.

Abstract: According to the invention, a process and system are disclosed for conditioning an oil or gas formation and the application of the various stimulating fluids to the oil or gas formation. The method consists of drilling from a vertical well hole a horizontal spiralling hole which spirals out into the oil or gas formation and around the vertical well hole. Other embodiments include the drilling of a horizontal inward spiralling well from a vertical well hole that inwardly spirals out into the oil or gas formation from the vertical well hole, and the drilling of a hole from a vertical well hole that spirals out and coils down through an oil or gas formation around the vertical well hole. The application of this process is contingent on the use of my remote control directional drilling system, U.S. Pat. No. 3,811,519, and my flexible drill pipe pending application Ser. No. 465,500, filed Apr. 30, 1974 on related equipment, now abandoned.

Abstract: An in situ oil shale retort is provided with a retort off gas cooling zone in the in situ retort at the product outlet end of the in situ retort. The kerogen in the in situ retort is converted to liquid and gaseous products by moving a heated gas through a retorting zone in the in situ retort and toward the product outlet end of the in situ retort. The movement of gas through the retorting zone is terminated when the retort off gas moving from the product outlet end of the in situ retort attains a temperature above which the temperature of the retort off gases will deleteriously effect product collection and removal apparatus in a collection zone adjacent to the product outlet end of the in situ retort. A reduced kerogen content of the oil shale in the retort off gas cooling zone as compared with the average kerogen content of oil shale in the in situ retort improves the yield of products from the in situ retort.

Abstract: An underground room in substantially undisturbed shale is filled with fragmented oil shale particles for in situ retorting. A comprehensive system is provided for feeding air to the top of the retort and recovering oil and flue gas from the bottom of the retort. The oil is separated from admixed water and both are recovered. Flue gas is withdrawn from the bottom of the retort, scrubbed clean and a portion may be recycled through the retort while another portion is vented or burned in a turbine. Means are also provided for passing scrubbed gas through a second spent shale retort prior to venting, burning or recycle.

Abstract: A method of extracting hydrocarbons in situ from an underground hydrocarbon deposit such as oil shale. A selected part of the deposit is heated by one or more electrical induction coils arranged in a quasi-toroidal configuration to temperatures high enough to drive off hydrocarbon fractions as gases or vapors, which are then collected and utilized in surface operations or recovered for transportation or temporary storage. The deposit may optionally be heated through a coking and cracking stage. Any remaining hydrocarbons may be burned in situ and the combustion gases utilized for energy. Steam may be obtained by injecting water into the heated shale after extraction of the hydrocarbons.

Abstract: The burn front in an in situ underground coal gasification operation is controlled by utilizing at least two parallel groups of vertical bore holes disposed in the coalbed at spaced-apart locations in planes orthogonal to the plane of maximum permeability in the coalbed. The combustion of the coal is initiated in the coalbed adjacent to one group of the bore holes to establish a combustion zone extending across the group while the pressure of the combustion supporting gas mixture and/or the combustion products is regulated at each well head by valving to control the burn rate and maintain a uniform propagation of the burn front between the spaced-apart hole groups to gasify virtually all the coal lying therebetween.

Abstract: A process for producing shale oil by circulating hot fluid through a rubble-containing cavern within a subterranean oil shale which contains water-soluble mineral is improved by burning a carbonaceous residue left within one cavity to produce hot fluid for operating power devices and also pyrolyzing the oil shale in a different cavity.

Abstract: A method of extracting hydrocarbons in situ from an underground hydrocarbon deposit (such as petroleum or lignite). A selected part of the deposit is heated by electrical induction to temperatures high enough to drive off hydrocarbon fractions as gases or vapors, which are then collected. The deposit may be heated through a coking and cracking stage. The electrical induction heating is conveniently effected by passing alternating current through a conductive path encompassing that part of the deposit to be heated.

Abstract: A technique is provided for cooling the flue gas or off gas from the bottom of an in situ oil shale retort. The gas is collected in a conduit that has a vertical portion through which the gas flows upwardly. It is then withdrawn from the retort through a gas tight bulkhead. Water is sparged downwardly through the vertical portion of the conduit for cooling and cleaning the gas. Means are provided for draining the sparged water into a sump at the bottom of the retort wherein oil and water are collected. Water and oil are separated and the water may be recycled for additional cooling.