Abstract: The vertical or both vertical and horizontal conformance of a stem drive process is improved by employing one or more infill wells between the injection well and production well, the infill well being in fluid communication with the bottom half or less of the formation. In the first step, petroleum is recovered from the infill well after oil production at the production well has proceeded to a predetermined point. After water cut of fluids being produced from the infill well reaches a predetermined value, the production well is converted from a production well to an injection well and steam is injected into the converted well while continuing recovering fluids from the infill well. When one infill well is employed in a more or less aligned arrangment between injection and production wells, the vertical conformance is improved. When one or more infill wells are utilized in a pattern comprising one or more injectors and one or more producers, both horizontal and vertical conformance is improved.

Abstract: An in situ coal gasification process adapted for large scale commercial projects is provided. Techniques are provided to insure establishment of a gasification front over the full seam thickness as each successive injection well in the array is brought on line. This is accomplished by controlling the oxidant introduction in a prescribed manner during the early stages of injection after pneumatic communication between well pairs has been established. Also provided are techniques and standards for avoiding or controlling subsidence and for conducting gasification operations in free water laden seams and in coal seams subject to spontaneous combustion.

Abstract: A method is disclosed for recovering viscous crudes from petroleum-containing formation, such as tar sand deposits, which are too deep to mine economically but not deep enough, or geologically not structured properly, to successfully hydraulically fracture for well to well production. The method contemplates a field grid layout of sets of injection and production wells and a subsurface generally horizontal heated tubular member passing through the subsurface petroleum-containing formation. Heated fluids are circulated through the tubular members to heat the viscous crudes in the vicinity of the tubular members and a heated drive fluid is injected through the injection wells to move heated crude toward the production wells.

Abstract: Disclosed is a method for conducting an enhanced oil recovery process comprising injecting an oil displacing fluid into an injection well and recovering petroleum displaced by the fluid from one or more spaced-apart production wells, by an improved method in which the sweep efficiency or horizontal conformance of the displacement process is increased. A fluid is injected into the producing well, which fluid has a viscosity not substantially greater than the viscosity of water at the conditions of injection, but which reacts with oil present in the formation, forming a viscous emulsion which restricts the flow of fluids through the portion of the formation contacted by the emulsion-forming fluid. As a result of this treatment, there is a reduction in tendency for the displaced and injected fluids to form cusps as they approach the production well, thereby failing to sweep substantial portions of the formation.

Abstract: A first casing is sonically driven into an earthen formation bearing a mineral such as oil. A second casing is similarly sonically driven into the same zone of the formation at a location spaced from the first casing. Water is pumped from the first casing into the formation. A series of piling members which may be in the form of sheets or may be tubular in shape are sonically driven into the formation at predetermined spaced positions between the two casings and with a predetermined orientation relative thereto. Sonic energy is simultaneously applied to the casings and piling members so as to cause resonant standing wave vibrations thereof while water is pumped through the first mentioned casing into the formation while mineral and water effluent are pumped out of the second casing. The sonic energy operates to loosen the mineral from the sand such that the pressurized water can effectively drive the oil to the second casing.

Abstract: A method of natural gas production from wells drilled into geopressured aquifers containing methane saturated water, comprising using wells which permit initial flow of water with a complete absence of back pressure at the well head, and containing the flow of water until loss of pressure in the aquifer exsolves sufficient gas to reverse the gas/water permeability ratio, thus converting the flow entirely to natural gas and water vapor and creating a gas cap. A further embodiment is the subsequent use of rings of secondary wells of similar design, each ring located at approximately equal radial distances from the initial well, to produce similar gas caps which interact with-, and produce from-, the gas cap created by production from the initial well and the gas caps of the other secondary wells.

Abstract: This invention relates to methods and systems for recovering high viscosity oils, petroleum substances and other minerals from subsurface earth formations. In particular, one or more large diameter shaft holes are provided which preferably terminate in an enlarged subterranean chamber. A plurality of drill holes are provided, with perforated piping which extend radially from the chamber into the formation, and from which oil and the like may be recovered. It is a particular feature of this invention to provide means and methods for injecting a mixture of steam and a noncondensable gas into the drill holes, whereby the driving mechanism of the formation may be selectively maintained or enhanced at the same time the viscosity of the oil in the formation is reduced.

Abstract: A method and apparatus are disclosed for restoring and/or maintaining an underground aquifer water supply system plagued with decreased water flow attributable to accumulation of undesirable flow impeding agents in the aquifer wherein a plurality of injection wells are drilled in the ground in surrounding relationship to the production well and a part of the water from the discharge thereof is treated with an additive capable of altering the nature of the plugging agents and returned to the aquifer via the satellite injection wells on a continuous basis. The proportion of bypass and recycle treatment water sent back to the aquifer may be varied with up to 50% normally being recycled for well restoration purposes while only about 10% need be returned for maintenance of the well flow at a desired level.

Abstract: A method for optimal placement and orientation of a well field for solution mining comprises first determining the direction and magnitude of the major and minor axes of transmissivity of the ore body. Then, determining the location of the injection and recovery wells based on the magnitude and orientation of the major and minor axes of transmissivity.

Abstract: An improved method of in situ mining of a mineral bearing stratum. The method comprises drilling alternating rows of vertical injection and recovery wells to the depth of an aquiferrous mineral bearing stratum. Two horizontal branches are drilled at the bottom of each injection and recovery well. The horizontal branches are substantially parallel to one another and lie within the mineral bearing stratum. Leachant fluid is pumped under pressure into the injection wells to dissolve the minerals contained in the stratum. Leachant fluid containing the dissolved minerals is pumped out through the recovery wells. The method of the present invention requires substantially less drilling and pipe for extracting minerals from a given volume of a mineral bearing stratum and results in more constant mineral extraction rates than conventional techniques.

Abstract: A method for electrical resistance heating of select portions of a natural underground reservoir, in a geologic formation, that contains both crude oil and water. Through selective resistance heating, oil viscosity is reduced in the select portion of the reservoir. Thus, portions which would not normally be contacted by injected fluids may be rendered susceptible to recovery by water flooding or other recovery process. Thermal expansion of heated oil also facilitates oil recovery. Resistance heating is accompanied by injection of low resistivity liquid that functions both as a conductor, through which current passes into the select portions, and as a medium for displacing oil to a production well. The low resistivity liquid also conveys convective heat, which contributes to viscosity reduction. Alternatively, the method of the invention can be used for altering the drainage pattern of a well.

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

Abstract: In one exemplar embodiment, method and apparatus include providing an electrode disposed in a plurality of insulated, spaced boreholes penetrating the oil formation. The plurality of electrodes in contact with a water electrolyte in the formation are connected to a source of AC electrical power for establishing a current flow between the spaced electrodes and through the oil bearing formation by means of the electrolyte. The electrodes are insulated from the earth structure surrounding the boreholes for preventing an electrical current path between the electrodes and the earth structure for isolating the electrical current path between the electrodes and the formation. When the AC current passing through the formation surpasses a minimum current density, AC disassociaton of the H.sub.

Abstract: An in-situ combustion method for oil recovery from a subterranean oil-bearing formation traversed by a plurality of wells comprising a series of well pattern units wherein air permeability is established sequentially in the individual well pattern units pior to the initiation of in-situ combustion, thereby resulting in an increase in overall sweep efficiency.

Abstract: A fluid injection induced oil recovery process wherein fluid is injected into a formation via a plurality of fluid injection wells and is produced from the formation via a plurality of production wells, and excessive flow and channeling through a "thief" region between one injection well and one production well is controlled by successively (1) shutting in the one injection well and operating the one production well for a first period of time and (2) operating the injection well and shutting in the production well for a second period of time. This sequence is repeated as many times as desired. The sequence can be modified by adding the additional step of (3) operating both wells for a third period of time. This alternative sequence is also repeated as many times as desired.

Abstract: The vertical conformance of a steam drive process is improved and steam override reduced by penetrating the zone between one injector and one producer, with an infill well which is in fluid communication with the bottom half of the formation, and producing petroleum from the infill well after steam channeling has occurred at the production well. After the water cut of the fluids being produced from the infill well reaches 95 percent, the infill well is converted from a producer to an injector and hot water is injected into the lower portion of the formation via the infill well and fluids are produced from the production well. By this means, oil is recovered from the lower portions of the formation adjacent the production well. After water breakthrough occurs at the production well, steam is injected into the infill well and fluids are recovered from the production well.

Abstract: The vertical or both vertical and horizontal conformance of a steam drive process is improved and steam override reduced by penetrating the zone between one injector and one producer, with one or more infill wells in fluid communication with the bottom half or less of the formation, and producing petroleum from the infill well after steam channeling has occurred at the production well. After the water cut of the fluids being produced from the infill well reaches 95 percent, the infill well is converted from a producer to an injector and steam is injected into the infill well and fluids are recovered from the production well. When one infill well is employed in a more or less aligned arrangement between injection and production wells, the vertical conformance is improved. When one or more infill wells are positioned in an offset or nonaligned arrangement relative to each injector and producer, conformance in both the horizontal and vertical planes is improved.

Abstract: The vertical conformance of a steam drive process is improved and steam override reduced by penetrating the recovery zone between one injection well and one producing well, with at least one infill well which is in fluid communication with no more than the bottom half of the formation. Steam or a mixture of steam and hydrocarbon is injected into the injection well and fluids including oil are recovered from the producing well until live steam production occurs at the producing well. Petroleum production is then begun at the infill well and continued until the water cut of the fluids being produced from the infill well reaches 95 percent. The infill well is converted from a producer to an injector and hot water or cold water followed by hot water is injected into thelower portion of the formation via the infill well and fluids are produced from the production well. By this means, oil is recovered from the lower portions of the formation between the infill well and the production well.

Abstract: The vertical conformance of a steam drive process is improved and steam override reduced by penetrating the zone between one injector and one producer, with an infill well located between the injector and producer which is in fluid communication with no more than the bottom half of the formation. Steam is injected into the injection well in the first phase with production of fluids from the upper 1/3 or less of the formation via the production well. A separate flow path in communication with the bottom 1/3 or less of the formation is provided in the producing well, and is used during the first phase for push-pull treatment of the formation with solvent and steam or hot water.

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

Abstract: The disclosure describes a technique for uniform heating of relatively large blocks of hydrocarbonaceous formations in situ using radio frequency (RF) electrical energy that is substantially confined to the volume to be heated and effects of dielectric heating of the formations. An important aspect of the disclosure relates to the fact that certain hydrocarbonaceous earth formations, for example raw unheated oil shale, exhibit dielectric absorption characteristics in the radio frequency range. In accordance with the system of the invention, a plurality of conductors are inserted in the formations and bound a particular volume of the formations. The phrase "bounding a particular volume" is intended to mean that the volume is enclosed on at least two sides thereof. Electrical excitation is provided for establishing alternating electric fields in the volume.

Abstract: A method of extracting oil from an underground bed of an oil-bearing mineral. The method comprises introducing a plurality of conduits into a first, lower part of the bed. Each conduit is spaced from its neighbors and includes a relatively coarse filter at its lower end and contains a relatively fine filter and a lift pump. A first conduit of the plurality of conduits extends to a depth less than the depth of its neighbors. The pressure in the first conduit is reduced. A solvent for the oil is introduced into those conduits at ambient pressure so that the solvent is drawn towards the first conduit and forms a flow path in the bed as it is drawn to the first conduit. The oil-solvent solution is pumped from the first conduit and the space left in the first area after extraction of the oil is filled with water.

Abstract: The disclosure describes a technique for uniform heating of relatively large blocks of hydrocarbonaceous formations in situ using radio frequency (RF) electrical energy that is substantially confined to the volume to be heated and effects dielectric heating of the formations. An important aspect of the disclosure relates to the fact that certain hydrocarbonaceous earth formations, for example raw unheated oil shale, exhibit dielectric absorption characteristics in the radio frequency range. In accordance with the system of the invention, a plurality of conductors are inserted in the formations and bound a particular volume of the formations. The phrase "bounding a particular volume" is intended to mean that the volume is enclosed on at least two sides thereof. Electrical excitation is provided for establishing alternating electric fields in the volume.

Abstract: A water bearing underground coal seam is prepared for production by in situ techniques by drilling a series of wells into the seam. Paths of maximum permeability are determined by taking oriented cores in selected wells. The coal seam is partially dewatered by removing water from the seam in selected wells. Reaction zones are established in the coal, first along the paths of maximum permeability, then reaction zones are established substantially perpendicular to the original paths of maximum permeability.

Abstract: A method of improving the sweep efficiency and increasing oil recovery of miscible flooding without reducing injectivity of the injection wells. Two sets of wells are used with one set being drilled between the other sets. The interwell area of a reservoir is pretreated by injecting a permeability-reducing agent (preferably a polymer) through said first set of wells. The polymer enters the more permeable zones and partially plugs them, both near and away from the wellbore. Thereafter, the injection or first set of wells are converted to producing wells. After the step of reducing the permeability contrast of the heterogeneous reservoirs, a miscible slug, that may or may not be preceded by a controlled salinity preflush, is injected into the second set of wells. There is no reduction in injectivity of the miscible injection wells, becuse no permeability-reducing agent has been injected therethrough.

Abstract: Disclosed is an oil recovery method especially useful for recovering viscous oil from thick formations including tar sand deposits. The method comprises several phases which accomplish efficient recovery of the viscous oil from the formation with good vertical and horizontal sweep conformance or effectiveness. The first phase may utilize as few as two spaced apart wells, one for fluid injection and one for oil production and an oil recovery method such as injecting steam or a mixture of air and steam for low temperature, controlled oxidation is a preferred fluid for use in the first phase. After fluid breakthrough at the production well occurs, the producer of the first phase is converted to an injection well and one or more new production wells outside of the pattern swept by the injected fluid are completed in the oil formation. Thermal recovery fluids are then injected into two wells with the displacement moving in the direction of the new production wells.

Abstract: Recovery of viscous petroleum such as from a thick tar sand formation is assisted using a closed-loop flow path formed in a production well extending from the earth's surface through a substantial portion of the formation for conducting hot fluid to reduce the viscosity of the petroleum in the formation to develop a first potential passage in the formation outside the flow path into which a hot drive fluid is injected through a injection well to promote movement of the petroleum to the production well for production and to develop a second potential passage for fluid flow in the formation from a linearly spaced apart injection well for injection of a hot drive fluid to further promote movement of additional petroleum to the production well.

Abstract: A method for the recovery of hydrocarbons from a subterranean hydrocarbon-bearing reservoir by an enriched gas drive wherein lean gas, evolved from the miscible transition zone, is produced ahead of the miscible transition zone and reinjected behind the solvent injection point whereby excessive gas production is utilized and a drive agent miscible with the solvent is provided to displace the reservoir fluids through the reservoir to a production well from which they are produced.

Abstract: In the oil-bearing formation wherein primary production has been exhausted and secondary recovery by waterflooding is exhausted or about exhausted, the residual brine is removed by progressive displacement. In this displacement a centrally disposed injection well or, preferably, lineal injection wells are utilized for the initial injection of preflush fluid with the immediately adjacent production and/or injection wells being shut in. After a specified slug of preflush has been injected, a series of chemical slugs is injected followed by drive fluid. After displacement of the residual brine has been effected out past the adjacent shutin wells, as evidenced by the arrival of the preflush, they are utilized as production wells. After oil sweep to these wells is complete, they are used as injection wells and the procedure is moved another step outward.

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

Abstract: A method of in situ solution mining is disclosed in which a primary leaching process employing an array of 5-spot leaching patterns of production and injection wells is converted to a different pattern by converting to injection wells all the production wells in alternate rows.

Abstract: A method for producing geothermal energy and minerals from subterranean high temperature and high salinity water reservoirs by injecting low salinity water at ambient surface temperature into the reservoir through a well bore, allowing the injected water to become heated in the reservoir and then producing water through the well bore to the surface for use as a source of energy and, optionally, minerals. Simultaneously with the employment of certain wells for injection-production cycles, other wells may be employed predominantly for injection of water to displace heat and in-situ well brines to well bores which produce such water and brines to the surface for utilization of their heat energy and dissolved minerals.

Abstract: A method of processing oil shale in which an in situ oil shale retort comprising an elongated cavity containing a fragmented permeable mass of formation particles containing oil shale is formed in a subterranean formation containing oil shale to recover liquid and gaseous products. Access to the cavity is by a drift or conduit at each end of the cavity and through a drift at an intermediate position. A processing zone is established in the fragmented mass at one end of the cavity and processing gas is introduced at that end of the retort and heating of the fragmented mass of formation particles is conducted from that end towards the other end. Initially, off gas is withdrawn at the intermediate drift. When the processing zone passes the intermediate drift, processing gas is introduced through the intermediate drift and off gas including gaseous products is withdrawn by way of the drift at the other end.

Abstract: In a method of constructing a filter well by forming a cavity, such as a bore, in the ground down to the level of the liquid-bearing zone of the strata and filling said cavity with a filtering medium such as filter gravel, the cavities are disposed so as to intersect along their length such that each cavity is in communication with at least one other cavity. In a preferred method, the cavity is formed and provided with a liner, and the liner is withdrawn as the filter medium is installed. Preferred arrangements of the cavities include single lines, intersecting lines, closed figures and especially circles occupied entirely by cavities, and lines radial to a central cavity.

Abstract: In one exemplar embodiment, method and apparatus include providing an electrode disposed in a plurality of vertically spaced boreholes penetrating the formation. The plurality of electrodes in contact with the salt water and oil of the formation are connected to a source of electrical power for establishing an AC electrical field of current flow between the spaced elctrodes. The electrodes are insulated from the earth structure surrounding the borehole for preventing an electrical current path between the electrodes and the earth structure for isolating the electrical current path from the electrode into the formation. The AC electrical current path through the formation generates volumes of free hydrogen in the formation where it is trapped for increasing the formation pressure. The increased pressure of the formation will drive the oil into producing boreholes spaced from the electrode boreholes.

Abstract: The present invention is directed to a method of recovering energy from a subsurface petroleum formation by igniting the petroleum reservoir and burning as much petroleum as is possible thereby generating heat and recovering the heat so that it can be transformed into other forms of useful energy. The method also includes the steps of controlling the burning reservoir by injecting plugging agents into the more rapidly burning channels of the reservoir and by injecting oxidizing agents in spaced locations from the heat recovery location so that the burn pattern can be spread out over a selected area to maximize the recovery of energy from the selected area.

Abstract: The method of the present invention relates to providing controlled directional bores in subterranean earth formations, especially coal beds for facilitating in situ gasification operations. Boreholes penetrating the coal beds are interconnected by laser-drilled bores disposed in various arrays at selected angles to the major permeability direction in the coal bed. These laser-drilled bores are enlarged by fracturing prior to the gasification of the coal bed to facilitate the establishing of combustion zones of selected configurations in the coal bed for maximizing the efficiency of the gasification operation.

Abstract: An arrangement is provided for recovering viscous oil from a tar sand formation having a large vertical dimension including a substantially vertical lined shaft extending through the tar sand formation. A first opening is formed in the lower portion of the shaft lining and at least one lateral hole extends into the formation through the first lateral hole. A plurality of tubular members are positioned in the lateral hole to provide both a closed loop flow path for fluid flow from the shaft into and out of the hole out of contact with the formation and a separate flow path for production fluids from the hole into the shaft. A steam source is connected to the tubular members forming the closed loop flow path. A second opening is formed in the shaft lining and a steam injection conduit extends through the second opening into the formation. The steam injection conduit is connected to the steam source for injecting steam into the formation.

Abstract: A method for recovering shale oil and gas from subsurface oil shale deposits in which free space is formed in the shale deposit and relieved blasting toward the free space from first shot holes drilled into the shale from the ground surface fills the free space with rubble. In-situ combustion of the rubblized shale decomposes organic material in the shale to form shale oil and gas, which are conveyed by combustion products through the shot holes to the surface, and leave a weak, easily compressible spent shale. After the in-situ combustion, shale surrounding the spent shale is rubblized by explosives detonated in second shot holes blasting toward the previously retorted zone. The second shot holes, which also are drilled from the surface into the shale, are spaced laterally from the first shot holes. The rubblized shale is then retorted by in-situ combustion. The successive rubblizing and in-situ combustion steps can be repeated to move the combustion operation laterally through the shale deposit.

Abstract: The orientation of hydraulically-induced fractures in relatively deep subterranean earth formations is normally confined to vertical projections along a plane parallel to the maximum naturally occurring (tectonic) compressive stress field. It was found that this plane of maximum compressive stress may be negated and, in effect, re-oriented in a plane projecting generally orthogonal to the original tectonic stress plane by injecting liquid at a sufficiently high pressure into a wellbore fracture oriented in a plane parallel to the plane of tectonic stress for the purpose of stressing the surrounding earth formation in a plane generally orthogonal to the plane of tectonic stress.

Abstract: In a combustion process for recovering hydrocarbons from a subterranean formation vertically traversed by an injection well through which an oxygen-containing gas is injected and a plurality of production wells through which liquid hydrocarbons and gaseous products of combustion are produced; oil recovery is improved by throttling of the production wells to increase the steam pressure in the locus ahead of the combustion zone, and according to a preferred mode, the combustion front advance is controlled by selectively throttling and increasing the gas pressure of production wells in the vicinity of the greatest advance of the combustion front.

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

Abstract: In a combustion process for recovering hydrocarbons from a subterranean hydrocarbon-bearing formation comprising an upper permeable hydrocarbon-bearing stratum overlying a lower permeable hydrocarbon-bearing stratum and separated therefrom by a semi-permeable stratum which is substantially permeable to oxygen but not substantially permeable to water; the strata are traversed by injection and production wells, the lower hydrocarbon-bearing stratum is ignited near an injection well and oxygen-containing gas is injected into the lower hydrocarbon-bearing stratum to combust hydrocarbons near the injection well and form a combustion front, an oxygen-containing gas is injected into the lower hydrocarbon-bearing stratum and an aqueous fluid is injected into the upper hydrocarbon-bearing stratum to move the combustion front between the injection and the production wells and to prevent or mitigate channeling through the upper hydrocarbon-bearing stratum, and hydrocarbons are recovered from the strata.

Abstract: In producing shale oil by circulating hot fluid into and out of void spaces within a subterranean oil shale, a plurality of cavities are formed around a central well, the cavities and the well are interconnected by leaching an areally extensive void space within a layer of water-soluble mineral, and hot fluid is circulated in through the cavities and out through the central well.

Abstract: In displacement processes for recovery of liquid hydrocarbons from a hydrocarbon bearing formation having zones of different permeability wherein such displacement processes comprise injecting a drive fluid through an injection well vertically traversing the formation and recovering by means of a production well the liquid hydrocarbons which are displaced by the injection of the drive fluid; this invention involves an improvement comprising injecting a water insoluble liquid into the permeable zone to increase drive efficiency in the less permeable zone.

Abstract: Method and apparatus for heating a subterranean formation in which a plurality of wells are completed in a predetermined pattern, characterized by heating the subterranean formation by electrical conduction under conditions such that the electrical current flowing at different subterranean points in the subterranean formation, or adjacent thereto, varies at different times because of different current flow patterns to attain a more nearly uniform heating of the subterranean formation. Also disclosed are a plurality of methods and apparatus, including the preferred embodiments of this invention.

Abstract: A method for operating an in situ combustion process in a petroleum containing reservoir wherein a plurality of air injection wells are spaced so that the approximate distance between the wells will be twice the distance at which the flux of air to the burning front from a single injection well becomes negligible.

Abstract: An improved method of recovering a fluid from a subterranean formation via heating by electrical conduction between a plurality of wells completed therein, the improvement comprising drilling and completing a satellite well open to the formation and adjacent an electrode well, injecting water containing dissolved electrolyte into the formation via the electrode well having an adjacent satellite well, establishing fluid communication between the electrode well and the satellite well, and circulating the water containing dissolved electrolyte between the electrode well and adjacent satellite well. This invention increases the electrical conductivity in the formation and about the wells where the current flux is greatest and makes possible larger current than would otherwise be possible with a given voltage differential. Also disclosed are specific embodiments.

Abstract: The disclosure describes a technique for uniform heating of relatively large blocks of hydrocarbonaceous formations in situ using radio frequency (RF) electrical energy that is substantially confined to the volume to be heated and effects of dielectric heating of the formations. An important aspect of the disclosure relates to the fact that certain hydrocarbonaceous earth formations, for example raw unheated oil shale, exhibit dielectric absorption characteristics in the radio frequency range. In accordance with the system of the invention, a plurality of conductors are inserted in the formations and bound a particular volume of the formations. The phrase "bounding a particular volume" is intended to mean that the volume is enclosed on at least two sides thereof. Electrical excitation is provided for establishing alternating electric fields in the volume.