Abstract: An in situ oil shale retort containing a fragmented permeable mass of formation particles having a generally uniform permeability across horizontal cross-sections of the retort is provided. To form the retort, underground formation is explosively expanded by explosive charges placed in a selected pattern. The combination of spacing distance and powder factor of central explosive charges is selected to produce a center portion of the fragmented permeable mass having a first average particle size (d.sub.1) and a first average void fraction (e.sub.1). The powder factor for perimeter explosive charges and the spacing distance between central charges and adjacent perimeter charges are selected to produce a perimeter portion of the fragmented permeable mass having a second particle size (d.sub.2) and a second void fraction (e.sub.2). The second average particle size (d.sub.2) and the second average void fraction (e.sub.2) are related to the first average particle size (d.sub.

Abstract: A method that produces a uniformly rubblized oil shale bed of desirable porosity for underground, in-situ heat extraction of oil. Rubblization is the generation of rubble of various sized fragments. The method uses explosive loadings lying at different levels in adjacent holes and detonation of the explosives at different levels in sequence to achieve the fracturing and the subsequent expansion of the fractured oil shale into excavated rooms both above and below the hole pattern.

Abstract: A method for collecting oil from a plurality of spaced-apart oil-bearing subterranean formations includes the steps of drilling a shaft from the earth's surface to a depth sufficient to intersect a plurality of spaced-apart oil-bearing formations, excavating a working area at selected oil-bearing subterranean formations and thereafter drilling a plurality of generally horizontal boreholes from each of the working areas into the selected oil-bearing subterranean formations. Thereafter, oil collection troughs are excavated within each of the working areas to collect oil from the boreholes and conduct the collected oil into a sump from which the oil is raised to the earth's surface utilizing a single lift. During collection and raising of the oil from each of the spaced-apart oil-bearing subterranean formations, the shaft and working areas are sealed.

Abstract: An in situ oil shale retort containing a fragmented permeable mass of formation particles having a generally uniform permeability across horizontal cross-sections of the retort is provided. To form the retort, a void is excavated in a subterranean formation within the boundaries of the retort site, while at least one zone of unfragmented formation is left adjacent the void. A plurality of explosive charges are placed in the zone of unfragmented formation in a selected pattern; an array of central explosive charges and a plurality of perimeter charges arranged in rows surrounding the central charges. The spacing distance between each row of perimeter charges and an adjacent outer row of central charges is about equal. The combination of spacing distance and powder factor of the central charges is selected to produce a center portion of the fragmented permeable mass having a first average particle size (d.sub.1) and a first average void fraction (e.sub.1).

Abstract: In situ oil shale retorts are formed in spaced-apart rows, with adjacent rows of such retorts being separated by load-bearing inter-retort pillars of unfragmented formation sufficiently strong for preventing substantial subsidence. Each retort contains a fragmented permeable mass of formation particles containing oil shale. An air level drift is excavated in formation directly above the inter-retort pillar so that the roof and/or floor of the air level drift is spaced above the upper boundaries of the retorts in such adjacent rows. This causes the roof of the air level drift to be in compression, rather than in tension, which stabilizes the roof and avoids dangerous rock falls. During retorting operations, air is introduced at the upper edge of each retort through lateral air inlet passages sloping downwardly from the air level drift. Off gas and liquid products are withdrawn from each retort through a production level passage at the bottom of each retort at the edge opposite the air inlet.

Abstract: A system for the extraction of a hydrocarbon fuel from a hydrocarbon fuel-bearing ore comprising means for mining the ore, a plurality of portative retorts for processing the mined ore to produce a hydrocarbon fuel, means for transporting the mined ore to each of said retorts, means coupled to said transport means for regulating the amount of ore transported to a respective retort, and at least one storage device coupled to the retorts for collecting and storing the hydrocarbon fuel. Also disclosed is the method of extracting a hydrocarbon fuel from a hydrocarbon fuel-bearing ore comprising the steps of mining the ore, transporting the ore to a plurality of portative retorts in which the ore is processed to produce a hydrocarbon fuel fluid, and moving the retorts in consonance with movement of the mining of said ore.

Abstract: An oil mining configuration primarily intended for use as a production drift for the recovery of petroleum from an overlying, oil bearing formation by gravity drainage. The configuration is in the general shape of a lollipop when viewed from above and has a stem portion and an annular head portion. The stem portion extends from a first location adjacent a main drift to a second location. The annular head portion extends from the second location about a vertical axis to a third location and on around to the second location to complete the lollipop shape. Production wells are drilled upwardly from the lollipop drift and the produced oil as well as gas and water are collected in tanks in the head portion and pumped up a service well extending from the head portion to the surface. Two methods of forming the lollipop drift are disclosed as are details of its design and operation including air flow and accidental spill recovery.

Abstract: In-situ hydrogenation of an underground coal formation is carried out by fracturing the formation and sealing it, to provide an in-situ reactor site. Then a liquid solvent stream and a gaseous hydrogen stream are introduced into the fractured formation, allowing reaction and conversion of the coal to lighter, hydrogenated components.

Abstract: A method for controlling the average particle size of a fragmented permeable mass of formation particles formed in an in situ retort in a subterranean formation containing oil shale is provided. At least one void is excavated in the subterranean formation, leaving zones of unfragmented formation above and below the void. Such a zone of unfragmented formation has naturally occurring cleavage planes and a substantially horizontal free face adjoining the void. An array of a plurality of substantially vertical blastholes is formed in at least one of the zones of unfragmented formation and each such blasthole is loaded with explosive for forming a substantially horizontal array of explosive charges. The spacing distance between adjacent blastholes or explosive charges in the array is from about 10 to about 15 times the average distance between cleavage planes when the oil shale formation has an average grade of more than about 20 gallons per ton.

Abstract: A method for forming an in situ oil shale retort in a retort site in a subterranean formation containing oil shale and having at least one set of naturally occurring cleavage planes is provided. The in situ oil shale retort contains a fragmented permeable mass of formation particles formed within top, bottom, and side boundaries of unfragmented formation. A void is excavated in the subterranean formation within the boundaries of the retort site, while a zone of unfragmented formation is left within the retort boundaries adjacent the void. A plurality of rows of horizontally spaced apart explosive charges is formed in the zone of unfragmented formation where each such row is in a line about perpendicular to the strike of the major cleavage plane set in the formation.

Abstract: The invention relates to an undersea system for the recovery of hydrocarbons, comprising at least one tunnel (13) extending from a terminal ashore to at least one chamber (1) adapted to accommodate drilling and other hydrocarbon recovery apparatus (3, 4).For the purpose of reducing or preventing damage due to a blowout or the like in such a chamber (1) with adhering tunnel or tunnels (13), the system according to the invention comprises in addition to the chamber (1) and tunnel or tunnels (13), at least one further chamber (6) which is adapted to receive and temporarily store hydrocarbons which unintentionally might appear in the first chamber (1) and to emit gaseous or liquid and/or solid hydrocarbon constituents through a tunnel (8) and/or pipe (7) for disposal and/or processing.

Abstract: A process for in situ recovery of a tar sand deposit located beneath the earth's surface. A number of boreholes are drilled laterally from subsurface tunnels into the lower portion of the tar sands formation. Initially as a displacing means such as steam is injected into the boreholes, the tar sands become viscous and gravity flow into the bottom of the boreholes. Continuing to apply steam removes the tar sand deposits located in interstitial crevices between the boreholes thereby allowing the steam to flow laterally through these interstitial crevices to nearby boreholes. The steam rises toward the upper portion of the resource formation to create a horizontal heated plane of steam to further remove tar sand deposits located therein.

Abstract: Method and system for characterizing a vertical modified in situ oil shale retort prior to ignition of the retort. The retort is formed by mining a void at the bottom of a proposed retort in an oil shale deposit. The deposit is then sequentially blasted into the void to form a plurality of layers of rubble. A plurality of units each including a tracer gas cannister are installed at the upper level of each rubble layer prior to blasting to form the next layer. Each of the units includes a receiver that is responsive to a coded electromagnetic (EM) signal to release gas from the associated cannister into the rubble. Coded EM signals are transmitted to the receivers to selectively release gas from the cannisters. The released gas flows through the retort to an outlet line connected to the floor of the retort. The time of arrival of the gas at a detector unit in the outlet line relative to the time of release of gas from the cannisters is monitored.

Abstract: A subterranean formation containing oil shale is prepared for in situ retorting by forming a fragmented permeable mass of formation particles containing oil shale in an in situ retort site. The retort is formed by excavating a lower level drift adjacent to a lower portion of the retort site and excavating an undercut within the retort site below a zone of unfragmented formation remaining within the retort site above the undercut. The bottom of the undercut slopes downwardly toward the lower level drift which opens into one side of the undercut, the slope being generally at the natural angle of slide of oil shale particles. The remaining zone of unfragmented formation is blasted downwardly toward the undercut in a series of lifts in sequence progressing upwardly in the retort site. The mass of formation particles formed during such blasting in lifts tends to slope downwardly toward the side of the retort adjacent the lower level drift.

Abstract: Following the conventional mining of rich oil shale for conventional above ground retorting, by horizontally extensive room and pillar mining operations, additional shale oil and related product may be secondarily recovered from the oil shale formation by in-situ retort formation and combustion. The secondary recovery steps would involve initially the identification of a large horizontally extending area, normally located between barrier pillars, which may be blocked off for the in-situ retort. Suitable shale oil drain arrangements may then be provided along one lower edge of this in-situ retorting area. Along the opposite lower edge of the in-situ retorting area, conduits may be provided for withdrawing product gas from the retort area. The retort area may then be sealed, and rubblized by blasting the pillars and caving in the roof to provide the appropriate 15% to 30% void volume for in-situ retorting.

Abstract: New and improved techniques, systems and equipment for the practical underground mining of petroleum from both virgin and depleted oil fields under certain geological conditions, are described. A method of drilling relatively small diameter, drainage-type oil wells using a fluid and cutting control assembly from within an access underground drilled tunnel, is provided. The fluid and cutting control assembly facilitates the safe underground drilling and installation of the small diameter, drainage-type oil wells which can be operated either under the natural pressures occurring in the geological strata, as gravity drain wells or by suitable secondary treatment measures artificially pressurized to facilitate drainage of oil from oil bearing strata into which such wells are drilled.

Abstract: A method for recovering oil by injecting an oxygen-containing gas containing at least 50 vol. % oxygen into the formation to initiate an in-situ combustion operation, separately producing oil and a flue gas from the formation, and separating carbon dioxide from the flue gas to produce a combustible gas.

Abstract: An in situ oil shale retort is formed in a subterranean formation containing oil shale by excavating one or more horizontally extending voids across a retort site, leaving a zone of unfragmented formation having a horizontal free face adjacent such a horizontal void. In one embodiment, such a horizontal void is excavated across less than the entire width of the retort site, leaving "side pillars" of unfragmented formation spaced inwardly from adjacent side boundaries of the retort site at opposite sides of such a horizontal void. This reduces the maximum span of the horizontal void, when compared with supporting overburden above the void with one or more interior isolated pillars spaced inwardly from the side boundaries of the retort. The side pillars are explosively expanded. Then such a zone of unfragmented formation is explosively expanded toward such a horizontal void for forming a fragmented permeable mass of formation particles containing oil shale in the retort.

Abstract: A method for collecting methane gas from subterranean formations having a plurality of spaced-apart coal seams containing methane gas includes the steps of drilling at least one shaft from the earth's surface to a depth sufficient to intersect a plurality of seams containing gas to be collected, excavating a working area at selected seams with each of the working areas communicating with the shaft, and drilling a plurality of boreholes from each of the working areas into the seams and collecting methane gas from the boreholes.

Abstract: A method for forming an in situ oil shale retort in a subterranean formation containing oil shale is provided. The in situ oil shale retort has top, bottom, and generally vertically extending side boundaries of unfragmented formation and contains a body of expanded oil shale formation that completely fills the retort to its top boundary. The retort is bulked full by explosively expanding a layer above a fragmented permeable mass of formation particles forming part of the body of expanded formation in the retort. The layer is expanded with an available void fraction of no more than about ten percent.

Abstract: A method for recovering liquid and gaseous products from an in situ oil shale retort containing a fragmented permeable mass of formation particles containing oil shale is provided. A hot ignition gas comprising oxygen at a first selected concentration is introduced into the fragmented mass for heating the fragmented mass top surface. The percentage of the fragmented mass surface that is at a temperature no less than the ignition temperature of oil shale is determined. Thereafter, the concentration of oxygen in the ignition gas is increased by an amount proportional to the determined percentage. Such heating of the fragmented mass top surface establishes a combustion zone in the retort. After the combustion zone has spread horizontally across the retort, introduction of the hot ignition gas is discontinued. Thereafter, an oxygen-supplying gas is introduced into the retort for advancing the combustion zone downwardly through the fragmented mass.

Abstract: A process is provided for forming an in situ oil shale retort which minimizes channeling, explosion gas turbulence and flame front tilting. In the process, explosives are detonated in an underground formation of oil shale to blast the oil shale into a permeable rubblized mass defining a retort, and gases emitted from the explosion are symmetrically vented. In the preferred form, the gases are vented through vertical vent holes and blast holes which extend through the top of the retort, as well as through a lateral access tunnel which extends into the bottom of the retort.

Abstract: An in situ oil shale retort is formed in a subterranean formation containing oil shale. The formation comprises at least one region of relatively richer oil shale and another region of relatively leaner oil shale. According to one embodiment, formation is excavated from within a retort site for forming at least one void extending horizontally across the retort site, leaving a portion of unfragmented formation including the regions of richer and leaner oil shale adjacent such a void space. A first array of vertical blast holes are drilled in the regions of richer and leaner oil shale, and a second array of blast holes are drilled at least in the region of richer oil shale. Explosive charges are placed in portions of the blast holes in the first and second arrays which extend into the richer oil shale, and separate explosive charges are placed in portions of the blast holes in the first array which extend into the leaner oil shale.

Abstract: A method for igniting an in situ oil shale retort containing a fragmented permeable mass of formation particles containing oil shale is provided. A void space is in the retort between the top surface of the fragmented mass and the top boundary of overlying unfragmented formation. A hot ignition gas comprising oxygen is introduced into the void space to form a combustion zone across the surface of the fragmented mass. An oxygen-supplying gas is then introduced into the void space for sustaining the combustion zone and for advancing the combustion zone downwardly through the retort. The combustion zone is then extinguished and a cool inert gas is introduced into the retort to cool carbonaceous materials comprising the surface of the fragmented mass to a temperature below the self-ignition temperature of such carbonaceous materials, while leaving carbonaceous materials below the fragmented mass surface at temperatures greater than the self-ignition temperature of such materials.

Abstract: An in situ oil shale retort is formed by excavating a lower level void adjacent the bottom boundary of a retort site in a subterranean formation, leaving a zone of unfragmented formation within side boundaries of the retort overlying the void. At least a portion of the overlying zone is explosively expanded downwardly towards the void in a plurality of lifts. Vertical columnar explosive charges are placed in each lift and detonated in a single round with a time delay between successive lifts sufficient for formation of the first lift to move out of the way and not interfere with initial explosive expansion of formation in the next successive lift. Preferably, the explosive charges in a second lift are detonated after detonation of explosive charges in a first lift with a time delay in the range of from about five to thirty milliseconds per foot of burden distance of the charges in the second lift.

Abstract: A method for forming an in situ oil shale retort in a retort site in a subterranean formation is provided. The in situ oil shale retort contains a fragmented permeable mass of oil shale particles formed within top, bottom, and side boundaries of the retort site. At least one void is excavated in the subterranean formation within the boundaries of the retort site, while a zone of unfragmented formation is left within the boundaries of the retort site adjacent such a void. An inlet is formed in a zone of the retort adjacent the intersection of a first side boundary of the retort site and the top boundary of the retort site and an outlet is formed in a zone of the retort adjacent the intersection of a second side boundary of the retort site and the bottom boundary of the retort site. The second side boundary is on the opposite side of the retort site from the first side boundary.

Abstract: In situ oil shale retorts are formed in spaced apart rows, with adjacent rows of such retorts being separated by load-bearing barrier pillars of unfragmented formation sufficiently strong for preventing substantial subsidence at the ground surface. Each retort contains a fragmented permeable mass of formation particles containing oil shale. Separate air level drifts are excavated on an upper level of the retorts within alternating barrier pillars, and separate production level drifts are excavated at a lower production level of the retorts within intervening barrier pillars between the barrier pillars having the air level drifts. Each air level drift extends between a pair of adjacent rows of retorts adjacent upper edges of the retorts in the adjacent rows, and each production level drift extends between a pair of adjacent rows of retorts adjacent lower edges of the retorts on sides of the retorts opposite the air level drifts.

Abstract: A row of horizontally spaced-apart in situ oil shale retorts is formed in a subterranean formation containing oil shale. Each row of retorts is formed by excavating development drifts at different elevations through opposite side boundaries of a plurality of retorts in the row of retorts. Each retort is formed by explosively expanding formation toward one or more voids within the boundaries of the retort site to form a fragmented permeable mass of formation particles containing oil shale in each retort. Following formation of each retort, the retort development drifts on the advancing side of the retort are closed off by covering formation particles within the development drift with a layer of crushed oil shale particles having a particle size smaller than the average particle size of oil shale particles in the adjacent retort.

Abstract: Formation is excavated from within the boundaries of a retort site in formation containing oil shale for forming at least one retort level void extending horizontally across the retort site, leaving at least one remaining zone of unfragmented formation within the retort site. A production level drift is excavated below the retort level void, leaving a lower zone of unfragmented formation between the retort level void and the production level drift. A plurality of raises are formed between the production level drift and the retort level void for providing product withdrawal passages distributed generally uniformly across the horizontal cross section of the retort level void. The product withdrawal passages are backfilled with a permeable mass of particles.

Abstract: Liquid and gaseous products are recovered from an in situ oil shale retort formed in a retort site in a subterranean formation containing oil shale. A void is excavated in the subterranean formation within the boundaries of the retort site and a zone of unfragmented formation is left in the retort site adjacent the void. A retort inlet is at one upper edge of the retort site and a retort outlet is at the lower edge of the retort site opposite the retort inlet.Explosive charges are placed in the zone of unfragmented formation and detonated in an asymmetrical time delay sequence for forming a fragmented permeable mass of formation particles which substantially fills the retort to the top boundary in the region of the retort inlet.

Abstract: A module of in situ oil shale retorts are formed in a row of retort sites in a subterranean formation. Each retort has top, bottom, and side boundaries of unfragmented formation and contains a fragmented permeable mass of formation particles. Two cross drifts are excavated through the retort sites along the row. One of the drifts is at a lower elevation near the floor of voids to be formed in the retort sites and along one side boundary of the retort sites. The other drift ramps upwardly at an end of the row for extending through the retort sites at a higher elevation near the roof of the voids excavated in the retort sites and along the opposite side boundaries of the retort sites. A horizontally extending slice is excavated at the elevation of the higher drift extending substantially to the side boundaries of a retort site for commencing a void within the retort site. The balance of the void is formed by benching from the slice to the elevation of the lower drift.

Abstract: A fragmented permeable mass of formation particles containing oil shale and having a substantially uniformly distributed void fraction is formed in an in situ oil shale retort in a subterranean formation containing oil shale. The fragmented mass is formed by explosive expansion towards a horizontal free face. At least one generally horizontally extending void is formed in the subterranean formation and zones of unfragmented formation are left above and below such a void. An array of horizontally spaced apart substantially vertical columnar explosive charges is formed in at least one of the zones of unfragmented formation. The array of explosive charges includes a plurality of central explosive charges which are spaced apart from side boundaries of the retort and a plurality of outer explosive charges surrounding the central charges.

Abstract: Product yield and quality is increased during in situ retorting of oil shale by pulsed combustion in which the flow of feed gas to the flame front is intermittently stopped while continuously retorting the oil shale. A purge gas can be injected into the retort between pulses of feed gas to enhance transfer of sensible heat from the combustion zone to the retorting zone and enlarge the separation between the combustion zone and the advancing front of the retorting zone.

Abstract: An in situ retort and process are provided for underground retorting of oil shale. The in situ retort is formed with at least one flame front-stabilizing layer of minute lean oil shale particles which serves as a redistribution region or grid. When the flame front is ignited and passed through the retort with a feed gas, the flame front-stabilizing layer will stabilize and enhance horizontal uniformity of the flame front to substantially minimize burning of the product shale oil.

Abstract: An in situ process and ignition procedure are provided to retort oil shale which increases product yield and enhances uniformity of the flame front in an underground retort. In the process, a portion of the rubblized mass of oil shale is preheated with steam, nitrogen or some other inert gas, to at least the minimum oil shale ignition temperature and preferably retorted. Thereafter, the preheated oil shale is ignited with hot excess air or some other oxygen-containing gas above the maximum desired retorting temperature to establish a generally uniform flame front across the retort. In the preferred form, the preheating gas and oxygen-containing gas are introduced into the retort at different times from the same specially configured downhole burner.

Abstract: An in situ oil shale retort is formed in a subterranean formation containing oil shale and having horizontal cleavage planes extending parallel to the bedding of the formation and approximately orthogonal vertical cleavage plane sets extending perpendicular to the horizontal cleavage planes. The in situ retort is formed by excavating an opening or void in a retort site in the formation and placing explosive in the formation adjacent the void such that the explosive can fracture formation along the vertical cleavage planes and expand remaining formation within the retort site toward the void, forming a fragmented permeable mass of formation particles containing oil shale within the retort site.

Abstract: An in situ oil shale retort is formed in a subterranean formation containing oil shale and having a substantially vertically extending first cleavage plane set and a substantially vertically extending second cleavage plane set intersecting the first set. The dispersion of the individual cleavage planes in the first and second cleavage plane sets is determined. The in situ retort is formed by excavating a vertical slot-shaped void within the boundaries of the retort site, leaving a remaining portion of the unfragmented formation within the retort site which is to be explosively expanded toward the slot. The unfragmented formation adjacent the slot has a pair of longer vertical free faces substantially aligned with the cleavage plane set having the lower dispersion. A pair of shorter vertical side walls of the slot can extend substantially perpendicular to the cleavage plane set having the lower dispersion.

Abstract: A method for forming a fragmented permeable mass of oil shale particles in an in situ oil shale retort in a subterranean formation containing oil shale is provided. At least one void is excavated within the retort site in the subterranean formation while zones of unfragmented formation are left adjacent such a void. The zones of unfragmented formation are then explosively expanded toward the void for forming the fragmented permeable mass of formation particles in the retort. To provide a fragmented mass with a flat top surface and reasonably uniform void fraction distribution, at least one of the zones of unfragmented formation is explosively expanded toward the void in a plurality of contiguous regions. Each such contiguous region has a free face adjacent the void and is expanded by first explosively expanding a first portion of that region toward the void. The free face of the first portion expanded is near the center of its respective region.

Abstract: Improved methods and apparatus are provided for recovering high viscosity oils from sub-surface earth formations. In particular, a large diameter shaft hole is employed and a plurality of substantially horizontal drill holes extend radially from the shaft hole into the formation. It is a feature of this invention to provide vertically spaced drill holes oriented to improve the recovery of the oil. Methods are provided for further enhancing oil recovery by coordinating the injected fluid with the location of injection within the formation.

Abstract: An array of explosive charges is formed in a retort site in a subterranean formation containing oil shale. The explosive charges that are located around the perimeter of the retort site are smaller than the explosive charges located more remote from the perimeter. Formation within the retort site is explosively expanded toward a void formed in the site by detonating the explosive charges. This explosive expansion of formation results in a fragmented permeable mass of formation particles in the retort. Damage to objects near the retort site, which is caused by seismic shock from the detonations, is minimized by using smaller explosive charges around the perimeter than in the center of the retort site.

Abstract: A two-pass in situ oil shale retorting system uses two separate gas levels for withdrawing off gas from producing in situ oil shale retorts. During a first pass of retorting through an oil shale tract, spaced apart groups of in situ oil shale retorts are formed, leaving intervening barrier pillars of unfragmented formation between adjacent groups of retorts. During retorting, off gas from the retorts formed in the first pass is withdrawn to a first gas level drift system. Thereafter, during a second pass of retorting, intervening groups of in situ oil shale retorts are formed in the intervening barrier pillars between the groups of in situ retorts formed in the first pass. During retorting in the retorts formed in the second pass, off gas is withdrawn to a second gas level drift system that is formed at a different level and isolated from the first gas level drift system so that gas flow between the two gas levels is avoided.

Abstract: There is provided a method for forming an in situ retort containing a fragmented permeable mass of formation particles in a retort site within a subterranean formation. A void is excavated into the formation and a zone of unfragmented formation is left adjacent the void. A plurality of explosive charges are formed in the zone of unfragmented formation. At least one central explosive charge is in a central portion of the zone of unfragmented formation, and a plurality of outer explosive charges are in the zone of unfragmented formation nearer the side walls of the void than the central explosive charge. The distance from each such outer explosive charge to an adjacent side wall of the void is about equal to the crater radius of the outer explosive charge. The central and outer explosive charges are detonated for explosively expanding the zone of unfragmented formation toward the void for forming a fragmented permeable mass of formation particles in the in situ retort.

Abstract: A method for conditioning a coal seam prior to in-situ gasification to increase the permeability of the coal seam to the flow of combustion-supporting gas therethrough and thus increase the efficiency of gasification wherein a wettability alteration fluid is injected into the coal seam via an injection well and fluids including the wettability alteration fluid are recovered from a spaced apart production well. Injection of the wettability alteration fluid is continued into the coal seam until the permeability thereof to the flow of the combustion-supporting gas therethrough has increased to a maximum extent. Suitable wettability alteration fluids include carbon dioxide, volatile amines, aqueous solutions containing phosphates, phenols, flue gas and alcohols, and mixtures thereof.

Abstract: A method and a cutter for producing a large cavity filled with a uniform bed of rubblized oil shale or other material, for in situ processing. A raise drill head (72) has a hollow body (76) with a generally circular base and sloping upper surface. A hollow shaft (74) extends from the hollow body (76). Cutter teeth (78) are mounted on the upper surface of the body (76) and relatively small holes (77) are formed in the body (76) between the cutter teeth (78). Relatively large peripheral flutes (80) around the body (76) allow material to drop below the drill head (72). A pilot hole is drilled into the oil shale deposit. The pilot hole is reamed into a large diameter hole by means of a large diameter raise drill head or cutter to produce a cavity filled with rubble.

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: A retort site in a subterranean formation containing oil shale is prepared for in situ retorting by excavating a void space in the retort site and then explosively expanding at least a portion of the remainder of the formation within the retort site toward the void space. The resultant fragmented mass explosively expanded toward the void space will be permeabilized by the void volume of the void space. The void space is initially formed by excavating at least three substantially parallel drifts through the retort site. At least two of the drifts are along opposed outside edges of the retort site and at least one drift is intermediate the two outside drifts. Excavation of the void space is conducted from the two outside drifts. A vertically extending slot is first excavated from each such drift upwardly into the proposed void space at one end of the retort site. The slot may be fanned above the drift so that the slots from the two outside drifts meet near the top of the void space.

Abstract: Oil shale is retorted, preferably in situ, by passing velocity flow of super-heated air through one or more conduit-like passages in direct contact with exposed surfaces of oil shale. Kerogen pyrolysis products are recovered by condensation of the vapors and collection of the condensate and by collection of the gases and separation of the valuable gases from the normally waste gases. Some of the waste gases may be recycled with the air for controlling combustion of the kerogen content of the shale.

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: A method of mining an oil deposit, wherein a plurality of underground workings with inlet and recovery galleries are provided in an oil-bearing bed. From the inlet galleries inlet wells are drilled, and from the recovery galleries--recovery wells. A heat carrier is supplied through the recovery wells to the oil-bearing bed and oil is extracted from the recovery wells. In so doing, each inlet gallery is arranged in the bed between two recovery galleries and near the faces of the recovery wells, while the inlet and recovery wells in the oil-bearing bed portions between the inlet and recovery galleries are drilled towards each other such that they should alternate to envelop the oil-bearing bed in a uniform network of wells.

Abstract: Subterranean mineral deposits, such as oil shale or the like, are prepared for in situ retorting by selectively mining out an area at the base of the deposit leaving an overlying deposit supported in a suitable manner such as by a plurality of pillars. The overlying deposit is expanded in any suitable manner into the underlying area in a fashion to create a predetermined distribution of permeability from an area of low permeability to an area of high permeability. An inlet is provided at the low permeability area and an outlet at the high permeability area. A suitable medium is introduced into the deposit at the low permeability end for extracting and forcing mineral values from the deposit toward the outlet end for recovery. .Iadd.