Abstract: A zone of increased heat and enhanced fluid mobility is established between an injection well and a production well vertically traversing a heavy oil (bitumen, tar) reservoir by (a) first horizontally hydraulically fracturing between the wells, and (b) then injecting hot water and/or steam into the injection well at a very high rate, at a sufficient pressure, and for a sufficient time (holding sufficient back pressure on the production well if needed) to float the formation along the fracture system between the wells, to effect channel flow of fluids through the floated fracture system (with production from the production well), and to effect effective and uniform heating of substantial reservoir volume perpendicular to the channel flow. Thereupon, other thermal methods such as matrix flow steam flooding can be employed to recover additional oil.

Abstract: A substantially flat combustion zone is established in a fragmented mass of particles containing oil shale in an in situ oil shale retort. By igniting a portion of the mass of particles, a heated zone including a combustion zone is established in the retort. For a first period of time, an oxidizing gas is introduced into the retort and heated zone at a rate sufficient to advance the heated zone through the fragmented mass. The locus of the combustion zone is monitored to determine if the combustion zone is substantially flat. If the combustion zone is not substantially flat, introduction of oxidizing gas into the retort is reduced temporarily for a second period of time to a rate such that the flow of heated gas through the retort for retorting oil shale in a retorting zone on the advancing side of the combustion zone is substantially reduced for a sufficient time to appreciably flatten the heated zone.

Abstract: Disclosed is a method and apparatus for controlling flame front advance in underground combustion of hydrocarbonaceous material by passing an oxidizing gas into the combustion area comprising providing a plurality of gas removal means positioned so that gas can be removed in the direction of the desired flame front advance; detecting flame front position in the combustion area; selectively removing gas from the retorting area in response to the detected flame front position through one or more of the gas removal means; so that flow of gas to portions of the flame front can be controlled, thereby controlling the advance of portions of the flame front in the desired manner. This method is especially useful in the underground in situ retorting of oil shale.

Abstract: The locus of a processing zone advancing through a fragmented permeable mass of formation 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 a halogen source in the permeable mass for providing an identifiable halogen and monitoring effluent fluid from the processing zone for presence of such halocarbon. The halogen source provides halogen at a predetermined temperature.

Abstract: The locus of a processing zone advancing through a fragmented permeable mass of formation 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 a radionuclide source for providing an identifiable radionuclide, and monitoring effluent fluid from the processing zone for presence of such radionuclide. The radionuclide source provides radionuclide at a predetermined temperature.

Abstract: A method is provided for recovering shale oil from a subterranean formation containing oil shale. Unfragmented formation is prepared for explosive expansion to form an oil shale retort by excavating at least one limited void in the subterranean formation and forming an array of spaced apart blastholes in the formation. A substantially horizontal array of explosive charges is formed by placing explosive into each blasthole wherein the scaled point charge depth of burial of the explosive charge in each blasthole is substantially equal to the equivalent scaled point charge depth of burial of the array of the explosive charges. Explosive charges are detonated in a single round for explosively expanding the unfragmented formation to form the in situ oil shale retort.Retorting is commenced and liquid and gaseous products of retorting are withdrawn from the retort.

Abstract: An in situ oil shale retort is formed with an upper surface of a fragmented permeable mass in the retort separated from a top boundary of unfragmented formation, creating an inlet plenum void. A primary combustion zone is established in the fragmented mass, and such primary combustion zone is caused to spread laterally by the establishment of a secondary combustion zone. During a first period of time, the temperature in the inlet plenum void is maintained at less than the temperature at which unfragmented formation from above the top boundary will slough into the void. The primary combustion zone is advanced through the retort and liquid and gaseous products of retorting are withdrawn. During a second period of time the temperature in the inlet plenum void is increased to increase the temperature of the top boundary of unfragmented formation to a temperature which will cause unfragmented formation from above the top boundary to slough into the void.

Abstract: A method for underground gasification of coal or brown coal, in which a substantially uniform gasification or combustion front is maintained by filling the cavity generated by gasification of coal with a filler so as to drive said front in an upward direction through the coal layer, the gases for maintaining the gasification being introduced through a first borehole and the combustion gases being discharged through a second borehole, one of these boreholes being used for introducing the filler, said boreholes extending at an inclination corresponding to the general inclination of the coal layer, and preferably converging towards one another.

Abstract: A method for recovering liquid and gaseous products from an in situ oil shale retort in a subterranean formation containing oil shale is disclosed. The method is practiced on an in situ oil shale retort having a plurality of fragmented permeable masses of formation particles with an upper and at least one lower fragmented mass. A zone of unfragmented formation intervenes between such fragmented masses and has a plurality of vertically extending holes for distributing fluid from the fragmented mass above to the fragmented mass below the zone of unfragmented formation. A processing gas is introduced to the upper fragmented mass and an off gas is withdrawn from the lower fragmented mass establishing a retorting zone in the upper fragmented mass and advancing the retorting zone downwardly through the upper fragmented mass, through such holes in the zone of unfragmented formation, and into and through the lower fragmented mass.

Abstract: A method of forming an in situ oil shale retort with an open space or inlet plenum void between the top boundary of the fragmented permeable mass of oil shale particles and the unfragmented formation above the retort. The method comprises excavating at least one horizontal void in the formation, placing explosive into the unfragmented formation above and below the void, and then explosively expanding formation above the void prior to explosively expanding formation below the void. The additional time for expansion of formation above the void, as compared with that below the void, permits non-uniform expansion and leaves an open space over the top of the fragmented mass.

Abstract: A method for elevating extremely large blocks of earth by displacement with a slurry composed of water and locally excavated materials. The blocks are separated on lateral faces by variously drilling, jetting, fracturing, and kerf cutting operations. The blocks are separated at the lower end by notching and hydraulic fracturing. Block movement is started by injecting gelled fluid into the narrow separations.In one set of applications the high density slurry filling the side clearances is less dense than the block being elevated. In these cases the earth blocks are displaced upward by injecting fluid into the underside, and the non hydrostatic component of the displacement pressure is contained by the gel strength of the slurry filling the narrow side clearance. In a second set of applications the blocks being elevated contain a high percentage of coal, and slurry filling the side clearances exceeds the block density. The blocks are then displaced upward by hydrostatic pressure.

Abstract: Bituminous coal is processed in situ for the recovery of values therefrom by drilling at least one borehole into the underground deposit, introducing a solvent for inclusions of resinous and other uncarbonized vegetable matter present in the coal, which solvent may or may not also be effective in some degree to dissolve carbonaceous matter, removing the solvent pregnant with the dissolved matter, so as to leave a substantially permeable area of coal in the deposit at and adjacent to the end of the borehole, igniting the coal at the end of the borehole, and removing products of combustion from the permeablized area while introducing a combustion-supporting gas into the area for advancing a heat front through the permeablized area.

Abstract: A method is disclosed for recovering liquid and gaseous products from an in situ oil shale retort having a plurality of strata of formation extending through the retort site with at least one stratum of formation having a higher average kerogen content than the average kerogen content of the formation within the retort site. The method includes the steps of excavating at least one void within the retort site and explosively expanding unfragmented formation toward such a void for forming a fragmented permeable mass of formation particles containing oil shale. The fragmented mass has a lower portion and an upper layer containing fragmented particles substantially from the stratum of formation having a higher average kerogen content. The upper layer of the fragmented mass has a higher average kerogen content than the average kerogen content of the fragmented mass. The upper layer is ignited for establishing a combustion zone in the fragmented mass.

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: 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 effluent water passing therefrom. The effluent water carries a constituent which is formed, by advancement of the processing zone through the fragmented mass, from a precursor contained in the formation. In a first aspect of the invention, the locus of the processing zone is determined by assaying the formation at selected locations in the retort for content of the precursor before processing the selected locations, and effluent water from the retort is monitored for concentration of the selected constituent. For example, the nitrogen content of kerogen can be the precursor and effluent water from the retort can be monitored for the concentration of ammonia and/or ammonium sulfate produced by retorting of kerogen in the oil shale.

Abstract: For the purpose of in-situ recovery of coal a borehole is driven from the surface in the plane of the coal over at least a large part of its travel, as far as conditions permit. At or near its end this borehole is widened over such a length and to such a width as corresponds with at least twice the deviation to be expected in the horizontal projection of a second borehole which is driven so far as to connect the widened section described above. The widened section is preferably made with the aid of mechanical means.After the boreholes have been linked, the coal is recovered by gasification, dissolution or extraction, whether or not under supercritical conditions and whether or not with attendant chemical/physical disintegration. The method according to the invention is particularly suited for use in the `in-line` gasification technique.

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: Oil shale formation is explosively expanded toward a limited void volume for forming an in situ oil shale retort in a subterranean formation containing oil shale. In one embodiment, a void in the form a narrow vertical slot is excavated within a retort site, leaving at least one portion of unfragmented formation within the retort site adjacent a vertical free face of the slot. Explosive is placed in a row of vertical blasting holes in the remaining portion of unfragmented formation adjacent the vertical free face. The blasting holes are mutually spaced apart along the length of the slot, and the row of blasting holes extends generally parallel to the vertical free face.

Abstract: A process of producing within a subterranean oil shale deposit a retort chamber containing permeable fragmented material wherein a series of explosive charges are emplaced in the deposit in a particular configuration comprising an initiating round which functions to produce an upward flexure of the overburden and to initiate fragmentation of the oil shale within the area of the retort chamber to be formed, the initiating round being followed in a predetermined time sequence by retreating lines of emplaced charges developing further fragmentation within the retort zone and continued lateral upward flexure of the overburden. The initiating round is characterized by a plurality of 5-spot patterns and the retreating lines of charges are positioned and fired along zigzag lines generally forming retreating rows of W's. Particular time delays in the firing of successive charges are disclosed.

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: Disclosed is a method for detecting the flame front during the in situ combustion of a subterranean carbonaceous stratum which involves providing one or more radio transmitters below the surface of the ground, each of said transmitters being capable of sensing and transmitting information concerning the physical and chemical properties of its surroundings, and monitoring said transmissions as an indication of the extent and movement of said flame front. Also disclosed is a method for detecting non-uniform packing characteristics of rubblized material which involves providing one or more radio transmitters within the boundaries of a retort capable of sensing and transmitting information concerning the physical parameters of its surroundings, and monitoring said transmissions as an indication of the size and density distributions of the rubble in said retort.

Abstract: Liquid and gaseous products are recovered from an in situ oil shale retort containing a fragmented permeable mass of formation particles by establishing a combustion zone in the fragmented permeable mass of particles. The combustion zone is advanced through the fragmented mass of particles by introducing a retort inlet mixture comprising oxygen into the retort on the trailing side of the combustion zone. The retort inlet mixture is maintained at a sufficiently high temperature of at least 1150.degree. F. so that the temperature of at least a portion of the fragmented mass on the trailing side of the combustion zone is maintained at a temperature of at least 1150.degree. F. for increasing the yield of hydrocarbon products obtained from the retort.

Abstract: An in situ oil shale retort containing a fragmented permeable mass of formation particles containing oil shale is formed in a subterranean formation containing oil shale. To retort oil shale in the retort, a primary combustion zone is established in the fragmented mass. A primary combustion zone feed containing oxygen is introduced to the primary combustion zone for advancing the primary combustion zone through the fragmented mass. A secondary combustion zone is established in the fragmented mass on the trailing side of the primary combustion zone. A retort feed mixture is introduced into the secondary combustion zone. The retort feed mixture contains sufficient fuel and oxygen for maintaining the secondary combustion zone and for forming a primary combustion zone feed containing oxygen for advancing the primary combustion zone through the fragmented mass.

Abstract: A method of producing hydrocarbonaceous liquids and gases from subterranean kerogen-containing oil shale formations comprising (a) penetrating the oil shale deposits with at least two well bores; (b) fracturing the oil shale deposits in a lower vertical portion thereof; (c) igniting the hydrocarbonaceous deposit; (d) introducing through the first well bore a free oxygen-containing gas to the ignited point of the oil shale deposit to effect thermal decomposition of the hydrocarbonaceous material therein and to propagate a combustion zone through the fractured communication area and the second well bore, thereby forming a region of combusted shale between the first well bore and the second well bore; (e) allowing the combustion to continue until a sufficient volume of combusted shale has been formed; (f) then jetting an aqueous liquid into and through the combusted shale zone to remove the mineral residue remaining after combustion; (g) positioning conventional explosives in the oil shale deposit in the vicinit

Abstract: In preparation for producing coal in situ two or more production wells are linked together through the coal seam by burned channels created by one or more blind hole burns.

Abstract: An in situ oil shale retort in which a cavity filled with broken particles of oil shale is formed within the subsurface oil shale formation and air is forced down through the cavity to sustain combustion of the top layer of oil shale particles, the products of combustion being withdrawn at the bottom of the cavity. A plurality of exhaust pipes traverse the bottom of the cavity and extend out through the sealed entrance to the retort cavity. The pipes are supported above the floor of the cavity and have holes opening on the bottom side of the pipes through which the product gases are withdrawn from the cavity. Valves in each pipe control the flow so as to balance the flow distribution of air and exhaust gases through the retorting cavity.

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: An in situ fragmented permeable mass of particles containing treated oil shale is formed by excavating a void in a subterranean formation containing oil shale, explosively expanding formation toward such a void to form a fragmented permeable mass of formation particles containing oil shale, and retorting the particles containing oil shale in the fragmented mass. Water containing impurities is introduced into such an in situ fragmented permeable mass of particles containing treated oil shale, i.e., retorted or combusted oil shale or both, for disposal, purification, or generation of steam. The water introduced can be water containing hydrocarbons such as process water from retorting oil shale or water containing suspended solids such as blowdown from a steam generator. When the fragmented permeable mass is still hot from retorting, steam is generated which can be withdrawn for use in oil shale recovery operations.

Abstract: The subterranean fragmented and pervious zone is formed beneath an overburden which, as a first step of the process, is lifted as a substantially monolithic land mass to produce a void space and a free space proximate the rock to be fragmented, the raised overburden thus providing a substantially impervious lid or closure for the fragmented zone as formed by the present invention. Explosive charges are then placed proximate to and for blasting against the free face formed on raising the overburden. The charges are exploded to fragment the rock to distribute the space, thus producing fractured, pervious rubble-ized rock in a defined and enclosed zone. Different techniques are disclosed for the critical raising of the overburden and subsequent fragmenting of the rock.

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 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: 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 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: 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: 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 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: 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: 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 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 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: 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: Leaching of water-soluble constituents from particles containing treated oil shale and including oxides of alkaline earth metals, such as particles in an in situ oil shale retort, is inhibited by contacting the particles with carbon dioxide in the presence of water for a sufficient time to produce a substantially water-insoluble and/or impermeable barrier of carbonates of alkaline earth metals at the surface of the particles.

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.