Abstract: A passive method for locating the position and inclination of a flame front, within an oil-shale retort of known dimensions and location during an in situ combustion of the retort involving detecting the sound generated by the flame front, by two matched detectors separated by a fixed known distance. The pair of matched detectors are suspended vertically in a liquid-filled well which was drilled essentially parallel to the side wall of the retort. The outputs of the two detectors are fed directly to a differential amplifier and the resulting difference signal is monitored as a function of depth as the pair of detectors are raised and/or lowered in the well. The minimum in this signal corresponds to the position of the flame front within the retort. Repeated measurements in various observation wells establish the inclination of the flame front.

Abstract: An in situ oil shale retort is formed in a subterranean formation containing oil shale. The formation comprises at least one stratum of relatively higher average kerogen content which is included in formation of relatively lower average kerogen content. A void is excavated in a retort site in the formation, leaving a remaining portion of unfragmented formation within the retort site adjacent the void. The portion of unfragmented formation within the retort site is explosively expanded toward the void to form a fragmented permeable mass of formation particles containing oil shale in an in situ retort in which fragmented formation particles from the stratum of higher kerogen content have a larger void fraction than the averge void fraction of the fragmented mass. This can be accomplished by enlarging the void in the vicinity of the stratum having the higher kerogen content prior to explosive expansion.

Abstract: A method of extracting hydrocarbon from an underground strata, wherein the hydrocarbon has high in situ viscosity, by the steps of forming a vertical access hole from the earth's surface to a point below the strata, the diameter of the access hole being sufficient to permit passage of workmen and machinery, mining an elongated horizontal shaft from the vertical access hole under the strata, establishing at least one drilling station in the horizontal shaft, drilling upwardly from the drilling station a plurality of wells into the hydrocarbon strata, the wells being spaced apart and preferably drilled so as to be substantially vertical in the hydrocarbon strata, injecting a viscosity reducing agent into one or more of the wells to reduce hydrocarbon in the strata to free flowing liquid, withdrawing the free flowing hydrocarbon from the strata through one or more of the wells, and pumping the withdrawn hydrocarbon to the earth's surface.

Abstract: A processing zone advances through a fragmented permeable mass of particles containing oil shale in an in situ oil shale retort in a subterranean formation containing oil shale. The fragmented mass has layers of formation particles of differing composition, such as kerogen content, corresponding to strata of differing composition in the formation. The processing zone advances in a direction substantially perpendicular to such layers in the fragmented mass. Kerogen in oil shale is decomposed to produce gaseous and liquid products including shale oil, and shale oil is withdrawn from the retort. At least one characteristic of the shale oil withdrawn from the retort varies in response to differences in composition of such layers of formation particles through which the processing zone advances. Such a characteristic can be a physical property of the shale oil such as viscosity or specific gravity, or a chemical property such as sulfur content or trace metal content.

Abstract: A processing zone advances through a fragmented permeable mass of particles containing oil shale in an in situ oil shale retort in a subterranean formation containing oil shale. The retort has an inlet gas introduced thereto and an effluent gas withdrawn therefrom. To determine the locus of the processing zone, kerogen content of formation at selected locations in the retort is determined before processing the selected locations. Because the difference in pressure between the inlet gas and the effluent gas increases as the kerogen content of formation being processed increases, changes in pressure drop across the fragmented mass can be predicted. By comparing actual changes in pressure drop with predicted change in pressure drop, the locus of the processing zone can be determined.

Abstract: A method of producing fluid fuels from carbonaceous deposits such as oil shale, heavy oils and coal by in-situ retorting of the carbonaceous deposit in rubblized in-situ retorts utilizes a plurality of such retorts. The retorts are subjected to a sequence of preparation for rubblization, rubblization and combustion of carbonaceous material to supply heat to produce a fluid fuel from kerogen in the carbonaceous deposit. At least one completely rubblized retort is maintained throughout its entire volume under the inlet pressure of the combustion air between retorts in which rubblization or stopping is taking place and retorts in which the combustion of the carbonaceous deposit is proceeding to prevent flow of toxic gases from the retort in which combustion is proceeding to a retort in which preparation for rubblization and rubblization are occurring. The invention is described in detail for the recovery of shale oil from oil shale deposits.

Abstract: This invention relates to novel leaching methods and apparatus for recovering minerals such as ores, high viscosity oil, and the like, from the subsurface earth formation. More specifically, the formation is penetrated by a plurality of mine shafts or large-diameter boreholes which are spaced apart as a function of the lithological characteristics of the formation. Thereafter, a suitable leaching fluid such as a liquid solvent, steam, free hydrogen, or carbon dioxide is injected into the formation through a plurality of drill holes radially extending from the lower portions of the shafts.In a particular technique for recovering high viscosity oil, the formation is initially subjected to a sequence of "soaking" cycles, wherein fluid is injected into the formation during separate discrete time periods, and wherein dissolved minerals or reduced viscosity oil is drained from the drill holes during the interval following each injection period.

Abstract: An improved process for recovering shale oil from in-situ shale comprising the steps of: (1) mining a first portion of said shale; (2) fragmenting a second portion of said shale; (3) introducing into said second portion a mixture of gases comprising a molecular oxygen supplying gas, carbon dioxide and hydrogen sulfide while maintaining a temperature sufficient to convert kerogen in said second portion to shale oil and to produce carbon dioxide, hydrogen sulfide, gaseous hydrocarbons and other combustion and inert gases; (4) separating said shale oil from an offgas containing said carbon dioxide, hydrogen sulfide, gaseous hydrocarbons and other combustion and inert gases; (5) separating hydrogen sulfide and a first portion of carbon dioxide from a gas of low sulfur content and increased heating value comprising said gaseous hydrocarbons and other combustion and inert gases and a second portion of said carbon dioxide; and (6) recycling said hydrogen sulfide and said first portion of said carbon dioxide to step

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: An in situ oil shale retort is formed in a subterranean formation containing oil shale. The retort contains a fragmented permeable mass of particles containing oil shale. An open base of operation is excavated in the formation above the retort site, and an access drift is excavated to the bottom of the retort site. Formation is explosively expanded to form the fragmented mass between the access drift and an elevation spaced below the bottom of the base of operation, leaving a horizontal sill pillar of unfragmented formation between the top of the fragmented mass and the bottom of the base of operation. The sill pillar provides a safe base of operation above the fragmented mass from which to control retorting operations. A plurality of blasting holes used in explosively expanding the formation extend from the base of operation, through the sill pillar, and open into the top of the fragmented mass.

Abstract: In-situ retorts of elongated rectangular shape in horizontal cross section are constructed in subsurface carbonaceous deposits in a plurality of parallel rows in each of which the retorts are arranged end-to-end. The rows are separated by unbroken pillars extending upwardly from rock that is not undermined or penetrated by retorts or tunnels. The ceilings of the retorts slope upwardly at an angle of at least 40.degree. with the horizontal to an apex or crown running longitudinally of the retorts to minimize the danger of roof collapse and provide a broadened pillar through which cross drifts opening into the crown of the retort extend for supplying combustion air. The crown of the ceiling is rounded to minimize concentration of the forces imposed by the overburden.

Abstract: An underground deposit of a carbonaceous material is retorted in an array of in-situ retorts arranged in a plurality of parallel rows. Each row of retorts is separated from adjacent rows by a pillar that extends unbroken for the length of the row. An apex drift extends longitudinally of each row and forms the crown of the retorts in that row. Combustion air for the retorting of the deposit in rubblized retorts in one row is supplied through the apex drift of an adjacent row. Delivery of combustion air into the crown of a retort for the retorting of the rubblized oil shale is through cross drifts from the apex drift of the adjacent row of retorts. Following combustion of the deposit in retorts in the first row, retorts are constructed and rubblized in a second row with the apex drift through which air had previously been supplied forming the crown of the retorts in the second row. Air for retorting deposit in the second row of retorts is delivered through a third apex drift.

Abstract: A subterranean formation containing oil shale is prepared for in situ retorting by initially excavating at least one void adjacent a zone of unfragmented formation to be expanded. The zone of unfragmented formation has a substantially horizontal free face adjoining the void. At least one support pillar of unfragmented formation is left in the void for supporting overlying formation. Explosive is placed in the zone of unfragmented formation, and in such a support pillar. Explosive in such a pillar and in the zone of unfragmented formation is detonated in a single round of explosions with a time delay between detonation of explosive in such a pillar and detonation of explosive in the zone of unfragmented formation for first expanding such a pillar toward the void and then expanding unfragmented formation toward the void. The time delay is sufficient for creation of free face at the juncture of such a pillar and the zone of unfragmented formation.

Abstract: An in situ oil shale retort is formed in a subterranean formation containing oil shale. The retort contains a fragmented permeable mass of particles containing oil shale. An open base of operation is excavated in the formation above the retort site, and an access drift is excavated to the bottom of the retort site. Formation is explosively expanded to form the fragmented mass in the retort between the access drift and an elevation spaced below the bottom of the base of operation, leaving a horizontal sill pillar of intact formation between the top of the retort and the bottom of the base of operation. The sill pillar has a vertical thickness sufficient to maintain a safe base of operation above the retort after the fragmented mass is formed.

Abstract: The locus of a processing zone advancing through a fragmented permeable mass of particles in an in situ oil shale retort in a subterranean formation containing oil shale is determined by withdrawing a sample of gas passing through the retort through a channel through unfragmented formation and in fluid communication with the retort, and analyzing the composition of withdrawn gas. The channel can be artificially formed such as by hydraulic fracturing of unfragmented formation, or can be a naturally occurring permeable layer such as a tuff bed in the formation containing oil shale.

Abstract: A retorting zone advances through a fragmented permeable mass of particles containing oil shale in an in situ oil shale retort in a subterranean formation containing oil shale. The fragmented mass comprises layers of formation particles of differing kerogen content corresponding to strata of differing kerogen content in the subterranean formation. The retorting zone advances in a direction substantially perpendicular to such layers in the fragmented mass. Kerogen in oil shale in the retorting zone is decomposed to produce gaseous and liquid products including shale oil, and shale oil is withdrawn from the fragmented mass. The rate of shale oil production in the retort depends upon th kerogen content of such a layer in such a fragmented mass through which the retorting zone advances.

Abstract: An apparatus is provided for determining the locus of a processing zone which advances through a fragmented permeable mass of particles in an in situ oil shale retort in a subterranean formation containing oil shale. The apparatus, which functions by releasing means for providing an indicator at a preselected temperature, comprises container means, means for providing an indicator in the container, and means for releasing the indicator providing means at a selected temperature greater than ambient.

Abstract: An in situ oil shale retort containing a fragmented permeable mass of formation particles containing oil shale is formed in a subterranean formation. The void fraction of the fragmented mass is from about 10 to about 25 percent, and the weight average diameter of particles in the fragmented mass is from about 0.02 to about 0.3 foot. Combustion zone feed containing oxygen is introduced to a combustion zone established in the fragmented mass. The rate at which the combustion zone feed is introduced to the combustion zone is controlled for maintaining the modified Reynolds number of gas passing through the combustion zone in the range of from about 0.1 to about 20.

Abstract: An in situ oil shale retort is formed in a subterranean formation containing oil shale. The formation comprises at least one stratum of relatively higher average kerogen content which is included in formation of relatively lower average kerogen content. A void is excavated in a retort site in the formation, leaving a remaining portion of unfragmented formation within the retort site adjacent the void. The portion of unfragmented formation within the retort site is explosively expanded toward the void to form a fragmented permeable mass of formation particles containing oil shale in an in situ retort in which fragmented formation particles from the stratum of higher kerogen content have a lower surface area per unit volume than the average surface area per unit volume of the fragmented mass.

Abstract: The locus of a processing zone advancing through a fragmented permeable mass of particles in an in situ oil shale retort in a subterranean formation containing oil shale and which generates an effluent fluid is determined by placing an indicator source for providing an indicator, and monitoring effluent fluid from the processing zone for presence of indicator. The indicator source provides indicator at a predetermind temperature.

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: A method for retorting oil shale in an in situ oil shale retort includes the steps of excavating a void in a subterranean formation containing oil shale and placing combustible material in the void adjacent an ignition situs. Formation is then explosively expanded toward the void to form a retort containing a fragmented permeable mass of formation particles containing oil shale, the top layer of the fragmented mass adjacent an ignition situs containing such combustible material. The combustible material is then ignited for establishing a combustion zone in the retort.

Abstract: A tunnel is formed above an in situ oil shale retort in a subterranean deposit containing oil shale. A void is excavated in the retort site and remaining deposit in the retort site is fragmented by explosively expanding toward the void to form a subterranean cavity containing a fragmented permeable mass of particles containing oil shale. The top of the fragmented mass is spaced downwardly from the tunnel to leave therebetween a pillar of unfragmented deposit. A retorting gas is introduced into the retort through a plurality of sloping passages from the tunnel for retorting oil shale in the fragmented mass. The liquid and gaseous products of such retorting are removed from the bottom of the retort. A portion of the carbonaceous products are used for generating electricity. In working a large area of deposit, a plurality of retorts are arranged in rows and columns.

Abstract: A subterranean formation containing oil shale is prepared for in situ retorting by initially excavating a pair of spaced apart voids, leaving an intervening zone of unfragmented formation between the voids. The intervening zone has substantially parallel free faces adjoining the void. A plurality of elongated blasting holes are formed in the intervening zone of unfragmented formation, the longitudinal axis of each blasting hole being substantially perpendicular to the parallel free faces of the intervening zone. At least two deck loads of explosives are placed in each blasting hole, with each load being longitudinally spaced apart from each adjacent load by stemming. The loads of explosive are then detonated in a single round of explosions with a time delay between adjacent loads for expanding formation in the intervening zones toward both voids. The fragmented mass of formation particles is then retorted to recover shale oil from the oil shale.

Abstract: Shale oil is recovered from a horizontal oil shale deposit having an exposed vertical surface by:(a) tunneling a horizontal sloping tunnel under a portion of the deposit, optionally using material removed from the tunnel to form a service terrace,(b) shaping and lining the floor of the tunnel to form a covered sump sloping to the tunnel mouth,(c) explosively rubblizing the roof and walls of the tunnel, and(d) fireflooding the rubblized zone to retort the kerogen which produces shale oil at the tunnel face through the sump.The fireflood is preferably by wet combustion which can be either forward or reverse combustion. Oxygen containing gas can be injected through a vertical bore from the surface or from the tunnel face. In one embodiment, the fireflood is prevented from channeling across the top of the rubblized zone by leaving segments of the roof to project downward at intervals. The vertical surface of the deposit can be naturally exposed or exposed by a large diameter bore hole or a vertical mine shaft.

Abstract: Liquid and gaseous products are recovered from oil shale in an in situ oil shale retort containing a fragmented permeable mass of particles containing oil shale by retorting oil shale in the fragmented mass to produce gaseous and liquid products. The liquid products are withdrawn from the retort to a first level in unfragmented formation below the elevation of the bottom boundary of the retort. Gaseous products are withdrawn from the retort to a second level below the elevation of the first level.

Abstract: Sulfur dioxide is removed from a process gas by passing the process gas through a first fragmented permeable mass of particles containing treated oil shale and including alkaline earth metal oxides at a sufficient temperature to remove sulfur dioxide from the process gas. Gas containing sulfur dioxide from the first fragmented mass is passed through a second fragmented permeable mass of particles containing treated oil shale and including alkaline earth metal oxides. Water in the second fragmented mass combines with alkaline earth metal oxides in the second fragmented mass and sulfur dioxide in the gas from the first fragmented mass with resultant removal of sulfur dioxide from gas from the first fragmented mass.

Abstract: An in situ oil shale retort is formed in a subterranean formation containing oil shale. The retort contains a fragmented permeable mass of particles containing oil shale. An open base of operation is excavated in the formation above the retort site, and an access drift is excavated to the bottom of the retort site. Formation is explosively expanded to form the fragmented mass between the access drift and an elevation spaced below the bottom of the base of operation, leaving a horizontal sill pillar of unfragmented formation between the top of the fragmented mass and the bottom of the base of operation. The sill pillar provides a safe base of operation above the fragmented mass after it is formed. The fragmented mass is formed by, among other steps, drilling blasting holes from the base of operation down through the sill pillar and detonating explosive in the holes to form the fragmented mass of particles in the retort below the sill pillar.

Abstract: A row of horizontally spaced apart in situ oil shale retorts is formed in a subterranean formation containing oil shale. Each row is formed by excavating at least a pair of upper and lower retort access drifts at elevations within the top and bottom boundaries of the retort sites. The access drifts extend through opposite side boundaries of a plurality of retorts in such row. Each retort is formed by excavating upper and lower horizontal voids at the levels of the upper and lower retort access drifts, respectively, such voids being excavated laterally from the access drift within the side boundaries of the retort sites. Each retort is formed by explosively expanding formation toward the upper and lower voids within the boundaries of the retort site to form a fragmented permeable mass of particles containing oil shale in each retort.

Abstract: Disclosed is a process for the slurry backfilling of subterranean in situ oil shale retorts, especially the improvement comprising introducing a slurry of sand and water into the subterranean retort so as to form drainage paths for the removal of water from the slurry of spent shale and water.

Abstract: To recover liquid and gaseous products from a fragmented permeable mass of particles containing oil shale, a buffer zone containing retorted oil shale is established in the fragmented mass by passing a hot processing gas substantially free of free oxygen through at least a portion of the fragmented mass. Thereafter, a combustion zone is established in the buffer zone, and a combustion zone feed containing oxygen is introduced into the fragmented mass on the trailing side of the combustion zone. This advances the combustion zone through the fragmented mass and retorts oil shale in a retorting zone on the advancing side of the combustion zone. The thickness of the buffer zone is sufficient for reaction of most of the oxygen in the combustion zone feed with residual carbonaceous material in retorted oil shale in the buffer zone.

Abstract: Sulfur dioxide is removed from a gas stream by passing the gas through retorted oil shale particles containing alkaline earth metal oxides.

Abstract: Impurities are removed from impure water by introducing the impure water into a fragmented permeable mass of particles containing raw oil shale. The water introduced can be water containing hydrocarbons such as water obtained from retorting oil shale or water containing suspended solids such as blowdown from a steam generator. After introducing impure water into the fragmented permeable mass, the mass of particles can be retorted. This is particularly advantageous when the introduced water contains hydrocarbons because at least part of the hydrocarbons removed from impure water can be recovered by retorting.

Abstract: The hydrogen sulfide concentration of a gas of relatively higher hydrogen sulfide concentration is reduced by introducing the gas to a fragmented permeable mass of oil shale for contacting the oil shale in the substantial absence of free oxygen. This yields a gas with relatively lower hydrogen sulfide concentration which is withdrawn from the fragmented permeable mass of oil shale.

Abstract: The locus of a processing zone advancing through a fragmented permeable mass of particles in an in situ oil shale retort in a subterranean formation containing oil shale is determined by monitoring pressure in the retort. Monitoring can be effected by placing a pressure transducer in a well extending through the formation adjacent the retort and/or in the fragmented mass such as in a well extending into the fragmented mass.

Abstract: Disclosed is a method for providing communication with a subterranean oil shale retort. This method can be used to provide a means of introducing fluids, such as a slurry of spent oil shale in water, into a retort. The method for providing lateral communication with a subterranean oil shale retort containing a rubblized retortable mass of oil shale, said retort being substantially surrounded by a mass of unmined formation comprises drilling at least one hole through the unmined formation adjacent to the retort; and providing communication between at least one of said holes and an adjacent retort; so that said drill hole can be used to communicate fluids to said retort. Fluids can be introduced into a spent retort which will form a supporting structure within said retort.

Abstract: Values are recovered from a subterranean in situ oil shale retort containing a fragmented permeable mass of formation particles by passing a measuring gas through the retort to determine the presence of a blockage in the fragmented mass. If there is such a blockage, only a portion of the fragmented mass is processed and the portion of the fragmented mass having the blockage is left unprocessed. This is effected by introducing a processing gas to the retort at an intermediate location between opposing ends of the fragmented mass and withdrawing gaseous and liquid products of processing at an end of the fragmented mass remote from such blockage.

Abstract: Gaseous and liquid products discharged from the outlet of an in-situ retort for the retorting of oil shale are delivered into an underground separating chamber located substantially at the level of the bottom of the retort. The lower portion of the separating chamber is divided by a weir into a first sump adjacent the inlet end of the separating chamber and a second sump adjacent the outlet end of the separating chamber. Oil and water separate in the first sump and the oil overflows the weir into the second sump. Water is withdrawn at a level below the oil in the first sump and pumped to the surface. Oil is withdrawn from the second sump and pumped to the surface separately from the water.

Abstract: Disclosed is a process for removing acidic impurities from off-gases generated in the retorting of oil shale comprising contacting a rubblized mass of oil shale which has been substantially depleted in hydrocarbonaceous materials with water, so as to extract basic components from the mass; and contacting off-gases, which were generated during the retorting of oil shale and which contain acidic impurities, with the water containing basic components so as to substantially remove said acidic impurities from said off-gases.

Abstract: An in situ oil shale retort is formed in a subterranean formation containing oil shale. The retort contains a fragmented permeable mass of particles containing oil shale. An open base of operation is excavated in the formation at an elevation above the fragmented mass to be formed, and an access drift is excavated to provide access to the bottom of the retort site. Formation is explosively expanded to form the fragmented mass between the access drift and an elevation spaced below the bottom of the base of operation, leaving a horizontal sill pillar of unfragmented formation between the top of the fragmented mass and the bottom of the base of operation. The sill pillar provides a safe base of operation above the fragmented mass after it is formed. The fragmented mass is formed by, among other steps, drilling blasting holes from the base of operation down through the sill pillar and then detonating explosive in such holes to form the fragmented mass of particles in the retort below the sill pillar.

Abstract: An in situ oil shale retort is formed in a subterranean formation containing oil shale. The retort with top, bottom and side boundaries contains a fragmented permeable mass of particles containing oil shale. A base of operation is excavated at a working level in the formation. Means are excavated through the formation for access to a location underlying the base of operation. In one embodiment, a void in the form of a vertical slot is excavated in the site between the means for access and an elevation below the bottom of the base of operation, leaving a remaining portion which is to be expanded toward the void. This is designed to leave a horizontal sill pillar of intact formation between the top of the void and the bottom of the base of operation with a vertical thickness sufficient to maintain a safe base of operation after explosive expansion of formation to form the fragmented permeable mass of particles.

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: A technique is provided for forming, in a subterranean deposit containing oil shale, an in situ oil shale retort having boundaries of unfragmented deposit containing a fragmented permeable mass of particles containing oil shale. The technique is particularly useful where at least a portion of the deposition layers of the oil shale deposit within the boundaries of the retort being formed are bonded together as a competent or relatively strong bed resistant to fragmenting. A portion of the deposit within the boundaries of the retort being formed is excavated to form a void with a free face within the boundaries. A second portion of the deposit within the boundaries extending away from the free face includes at least one competent bed. At least one competent bed within the boundaries is fractured substantially parallel to the deposition layers for reducing the effective thickness of the competent bed.

Abstract: A method for creating a zone of relatively high permeability within a subterranean carbonaceous deposit which includes gasifying a portion of the carbonaceous deposit to provide a cavity, placing at least one explosive device in the deposit in the vicinity of the cavity so that energy generated upon detonation of the explosive device extends into the cavity, and detonating the explosive device thereby causing a portion of the carbonaceous deposit to be fragmented and to collapse into the cavity.

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: A row of horizontally spaced apart in situ oil shale retorts is formed in a subterranean formation containing oil shale. Each row is formed by excavating at least a pair of upper and lower retort access drifts at elevations within the top and bottom boundaries of the retort sites. The access drifts extend through opposite side boundaries of a plurality of retorts in such row. Each retort is formed by excavating upper and lower horizontal voids at the levels of the upper and lower right access drifts, respectively, such voids being excavated laterally from the access drift within the side boundaries of the retort sites. Each retort is formed by explosively expanding formation toward the upper and lower voids within the boundaries of the retort site to form a fragmented permeable mass of particles containing oil shale in each retort.

Abstract: In a process for recovering liquid and gaseous products from an in situ oil shale retort containing a fragmented permeable mass of particles containing oil shale, a heated zone is established in an upper portion of the fragmented mass. For a period of normal retorting operation, an oxygen containing gas is introduced to the fragmented mass on the trailing side of the heated zone at a sufficient rate for advancing the heated zone downwardly through the fragmented mass and liquid products and a relatively lean off gas containing gaseous products are withdrawn from the bottom of the retort. Thereafter, for a period of post-retorting operation, the introduction of gas to the fragmented mass is reduced to a rate such that a relatively rich off gas is withdrawn from the retort. The rich withdrawn off gas preferably has a heating value of at least about 75 BTU/SCF.

Abstract: Disclosed is a process for generating synthetic fuels from carbonaceous minerals such as oil shale and coal by dispersing a catalytic agent by suitable explosive means into carbonaceous deposits. The explosives serve to fracture and rubblize the carbonaceous mineral as well as conveying the catalyst onto and in close proximity to the fractured particles. The catalyst coated particles are then converted, in whole or part, to gaseous and liquid products by conventional processes such as retorting, gasification, hydroretorting, hydrogenation, or the like, wherein this process or part of it is accelerated, decelerated, or otherwise favored by the presence of the catalytic agent. This process is capable of producing an increased yield and/or better quality product since it is possible to maintain greater control over the conversion step.

Abstract: A previously mined underground coal deposit is sealed so that the underground void space can be pressurized for production by in situ techniques. Excavated communication passages are sealed by barricades which are further sealed by applying hydrostatic head pressure. Subsidence cracks are sealed by injection of mud slurry with additional sealing effected by maintaining hydrostatic head pressure with a column of the slurry. In situ production wells are drilled into the coal with hermetic seal accomplished in part by cementing a portion of the liner to the well bore and in part by the hydrostatic head pressure of a mud slurry positioned above the cement seal. Coal is ignited and burn patterns are established to cause reasonably uniform subsidence.

Abstract: The present invention provides a method of in situ extraction of bitumen from an oil-sands body which method comprises sinking an access shaft through the oil-sands body, driving an access drift in the rock strata underlying the oil-sands body, delineating a rectangular block of oil-sands in said body by drilling and blasting the oil-sands body to provide substantially vertical planes of fractured oil-sands on all four sides of an enclosed mining room capable of retaining liquids and gases under pressure and comprising solid pillar walls, providing generally upwardly extending bores in said block of oil sands from the access drift in the said body, providing perforated pipes in those portions of the bores in said block, the perforations of said pipes being dimensioned to prevent sand particles from said block passing therethrough, increasing the permeability of the block of oil sands within said room by fracturing said block, flooding the mining room with a hot fluid at a temperature and for a residence time