Abstract: The invention relates to an apparatus for severing tubular members and is provided with a carrier, which carries a sparging assembly and an explosive assembly downwardly into the tubular member to be severed. The outlet of the sparging assembly is below the lower end of the carrier and is at a level adjacent to the level of the explosive charge carried by the explosive assembly. The sparging assembly dislodges and agitates the debris accumulated within the tubular member and evacuates it from the level, wherein it is deployed, simultaneously allowing progression of the explosive assembly downward along the interior of the tubular member.

Abstract: A method for minimizing damage to downhole equipment utilized in controlled pulse fracturing (CPF) where a drag reducing fluid tamp is used. Said tamp has a viscosity sufficient to reduce the flowing pressure drop thereby diminishing frictional forces along fluid/solid interfaces. The CPF device is submersed in said tamp. Upon ignition of a CPF device, the upwardly traveling pressure forces the tamp of drag-reducing characteristics to pass the downhole equipment thereby minimizing tool and equipment damage. Afterwards, the pressure is allowed to leak off slowly into the formation.

Abstract: A method for minimizing damage to downhole equipment utilized during controlled pulse fracturing ("CPF") where an oil based thickened fluid is used as a tamp. A gelled oil based fluid overlies a CPF propellant device thereby creating a tamp. When the propellant contained in the device is ignited, this high viscosity gelled fluid prevents the remnant of said device and wireline from moving upwardly which minimizes damage thereto.

Abstract: A method for minimizing damage to downhole equipment utilized during controlled pulse fracturing ("CPF") where a shear thickening fluid is used as a tamp. A shear thickening aqueous fluid having particles therein overlies a CPF device thereby creating a tamp. Movement of the fluid by pressure forces resultant from the ignited propellant causes the fluid to thicken. This thickened fluid prevents and device and wireline from moving upwardly which minimizes damage thereto.

Abstract: An active combustion zone is established in situ within a permeable hydrocarbon formation. The permeable formation is periodically charged with a combustible gas, and is thereafter subjected to a high pressure pulse produced by detonation of the combustible gas within an injection well. The periodic pressure pulses drive the combustible gas into the in situ combustion zone. Combustion is sustained by injection of an oxidant. The injection of oxidant is terminated periodically, and the injection well along with the surrounding formation is pressurized and saturated with the combustible gas mixture. The combustible gas mixture is displaced through the permeable formation in advance of the combustion flame front in response to a high pressure pulse produced by detonation of the pressurized combustible gas within the injection well. In the preferred embodiment, the combustible injection gas is a mixture of hydrogen gas and chlorine gas.

Abstract: The present invention provides a method of consolidating an incompetent subterrnean formation. An acid curable resin consolidating fluid is positioned within casing in a wellbore in the vicinity of perforations through the casing. A gas generating charge positioned within the casing then is ignited to generate gas pressure which rapidly forces the consolidating fluid through the perforations and into the subterranean formation while substantially simultaneously catalyzing the resin composition. The consolidating fluid is caused to rapidly harden to consolidate the formation in the vicinity of the perforation without any significant permeability loss.

Abstract: A process for improved acidizing in carbonate formations, where controlled pulse fracturing (CPF) is utilized in combination with a retarded acid and a solidifiable gel. The solidifiable gel forms a solid formation gel in a zone of greater permeability and a gel plug in the wellbore. Said gel is formed from a melamine formaldehyde resin and a cross-linkable polymer. An inhibited acid is placed in an interval of said formation having lessened permeability. The retarded acid comprises hydrochloric, formic, acetic acid or mixtures thereof which is placed in a wellbore adjacent the area to be treated. Said acid can contain retarders and corrosion inhibitors sufficient to make said acid stable in the wellbore. At least one CPF device is placed in said acid near the interval to be treated. Upon detonation of said device, acid is forced into the interval of lessened permeability, thereby enhancing the acidizing treatmemt.

Abstract: An improved method of fracturing a geological formation surrounding a well bore is disclosed. A relatively small explosive charge is emplaced in a well bore and the bore is subsequently hydraulically pressurized to a pressure less than the formation breakdown pressure and preferably greater than the fracture propagation pressure of the formation. The charge is denoted while the bore is so pressurized, resulting in the formation of multiple fractures in the surrounding formation with little or no accompanying formation damage. Subsequent hydraulic pressurization can be used to propagate and extend the fractures in a conventional manner. The method is useful for stimulating production of oil, gas and possibly water from suitable geologic formations.

Abstract: A device for fracturing a subterranean formation includes a propellant charge which generates, during combustion, a large quantity of high pressure combustion products. A drogue is provided on the device to prevent or minimize rapid upward movement of the device during combustion. This obviates "bird nesting" of the wire line, wire line damage and the like.

Abstract: A process for decreasing total fluid flow through a large natural or induced fracture where smaller multiple fractures are created. These multiple fractures each have a smaller aperture than said natural or induced fracture. The combined fluid flow through said multiple fractures is sufficiently less than the total fluid flow through said large fracture, thereby decreasing fluid bypass and improving sweep efficiency.

Abstract: A process for improving the effectiveness of control pulse fracturing in a carbonate formation wherein a high energy impulse device having a metallic sheath reactive with a retarded acid is utilized in combination with a retarded acid. Upon placement of such device within a wellbore, the metallic sheath reacts with the retarded acid and generates heat which activates said acid. Afterwards, the high energy impulse device is ignited which fractures the formation and forces the activated acid into the created fractures thereby enhancing acid contact with said formation.

Abstract: A high energy gas fracturing tool for radially fracturing a rock formation in a well bore consisting of a cylindrical canister that is holed to pass gas and is for housing a stack of propellant modules that are selected to provide a desired burn rate when ignited. Each propellant module mating face is angled from the horizontal between forty-five (45) to seventy-five (75) degrees, and the modules are bonded together with an epoxy resin wherein propellant or explosive particles are mixed, the resin to exhibit burn characteristics similar to those of the propellant stack. The tool, additional to the propellant containing canister, an ignitor rod and explosive device for igniting the propellant stack, mounts a bull head end over a lower end and a reverse thruster assembly that is connected to the canister upper end.

Abstract: A perforating system for completing subsurface formations transversed by a borehole. A sub with a plurality of closed vent ports and a perforating gun are run into a borehole on the end of a tubing string. To initiate the perforating system an impact member is dropped through the tubing string. The impact member strikes a percussion firing head which initiates a detonation wave in a detonator cord. The detonation wave detonates an explosive pellet within the sub, the resulting explosion initiating a pressure wave which forcibly opens the vent ports and fluidly communicates the well bore to the tubing annulus. The detonation wave continues on in the detonator cord to actuate the perforating gun.

Abstract: A process for improved acidizing in carbonate formations, where controlled pulse fracturing (CPF) is utilized in combination with a retarded acid. The retarded acid comprises hydrochloric, formic, acetic acid or mixtures thereof which is placed in a wellbore adjacent the area to be treated. Said acid can contain retarders and corrosion inhibitors sufficient to make said acid stable in the wellbore. At least one CPF device is placed in said acid near the interval to be treated. Upon detonation of said device, acid is forced into the desired interval, thereby enhancing the acidizing treatment.

Abstract: An improved, simplified and less expensive apparatus and method for cleaning wells embodies an elongated tube of combustible material, sealed at its ends, that is ignited at one end to generate a pressure wave that travels along the length of the tube. Outwardly directed pressure generated within the well casing by the deflagration is periodically attenuated at spaced locations along the length of the tube by a plurality of spaced short, steel sleeves circumscribing the tube and secured thereto. Three such tube sections are provided, each with its spaced, short circumscribing steel sleeves and each ignited in a selected chronological and positional sequence by three individual simultaneously electrically activated detonator caps which are provided with mutually different delay times.

Abstract: A controlled pulse fracturing ("CPF") process where a viscous fluid is used as a tamp or fluid cushion above a propellant device. Use of said fluid increases the vertical drag in the open wellbore thereby maximizing injection into the formation. Increasing the vertical drag during the fracturing procedure maximizes the number, extent, and length of fractures.

Abstract: A method for effecting high impulse fracturing in a stratified formation penetrated by a well where multiple fractures are first induced in a lower zone. Thereafter, said fractures and the well area within and adjacent said lower zone are filled with a gel mixture which solidifies. A gel plug is thus formed in said lower zone. High impulse fracturing is instituted in a higher zone which is filled with a gel mixture similarly as in said lower zone. High impulse fracturing and forming a solid gel within the induced fractures and area within the well adjacent the fractured zone are continued until each desired zone has been fractured. The gel plug prevents high impulse energy from entering fractures of previously fractured zones resulting in deeper fracture penetration.

Abstract: A process for improving the effectiveness of control pulse fracturing in a carbonate formation wherein a two stage high energy impulse device is utilized in combination with a retarded acid. Upon placement of such device within a wellbore, the first impulse stage activates said acid. Afterwards, the second impulse stage fractures the formation and forces the activated acid into the created fractures thereby enhancing acid contact with said formation.

Abstract: A process for sequentially fracturing a subterranean formation containing desired natural resources in which controlled pulse fracturing (CPF) is combined with hydraulic fracturing in the same wellbore. After multiple radial vertical fractures have been created by CPF, a solidifiable gel material is directed into the created fractures during a subsequent hydraulic fracturing procedure. During this procedure, multiple vertical hydraulic fractures initiate in and propagate away from the CPF created fractures thereby bringing the wellbore into communication with the desired natural resources.

Abstract: A subterranean formation is fractured by burning a quantity of fuel in an uncased bore hole to generate a large quantity of high pressure combustion products. These gases rapidly flow into the formation creating the fractures. The device is assembled in the well by placing a thermal ignitor in the well and delivering a quantity of fuel and oxidizer around the ignitor. The fuel and oxidizer comprise a flowable material and are either pumped or poured into the well.

Abstract: A controlled pulse fracturing (CPF) process conducted with the addition of a proppant. Said proppant can comprise sand or similar material which is injected into the fluid adjacent to the perforations. Upon ignition of the CPF device, said proppant is injected into the created fractures, thereby propping said fractures open. This causes a production increase from the well. Said fluid can comprise water, a gel, a thixotropic fluid, or similar type fluids.

Abstract: Voids in a gravel pack, particularly in deviated wellbores, are substantially eliminated via a process which utilizes a high energy impulse device. Said device is lowered into the vicinity of the voids and detonated thereby causing turbulence through the screen or slotted liner which causes a re-adjustment of the pack. Energy from said device can be tailored to allow considerable agitation to the gravel pack and screen without destroying said screen.

Abstract: Oil is recovered from a subterranean oil-containing formation by fracturing the formation around the injection well and thereafter injecting a CO.sub.2 foam or a mixture of steam and a CO.sub.2 foam into the injection well to displace mobilized oil toward a production well for recovery.

Abstract: A method to enhance oil production from producing formations using a pressure differential created by evacuating a recovery hole cased through the overburden into the producing formation, and directionally injecting under pressure, into an injection hole in communication with the producing formation, a heated hydrocarbon solvent with surfactant added a distance from the recovery hole. The heat, solvent, pressure differential and surfactant will increase the flow of crude into the recovery hole.

Abstract: The effective permeability of subterranean hydrocarbon bearing formations with respect to surfactant and drive fluid injection processes is enhanced by preceding the surfactant fluid injection step with creation of multiple formation fractures using tailored pressure pulses produced by gas generating propellant canisters disposed in the injection well. Fluid injectivity rates are increased by subsequent fracture extensions provided by repeated steps of generating high pressure gas pulses at selected intervals.

Abstract: Subterranean oil and gas producing formations are fractured by providing one or more combustion gas generating units using rocket fuel type propellants disposed in a well casing at preselected depths. The well casing is filled with a compressible hydraulic fracturing fluid comprising a mixture of liquid, compressed gas, and propant material and precompressed to a pressure of about 1,000 psi or more greater than the fracture extension pressure at the depth of the zone to be fractured. At least one of the gas generating units is equipped with perforating shaped charges to form fluid exit perforations at the selected depth of the fracture zone. The gas generating units are simultaneously ignited to generate combustion gasses and perforate the well casing. The perforated zone is fractured by the rapid outflow of an initial charge of sand free combustion gas at the compression pressure followed by a charge of fracturing fluid laden with propant material and then a second charge of combustion gas.

Abstract: Method and apparatus for completing a plurality of zones in a wellbore. A packer having a tubular element extending therethrough is suspended in a wellbore between two hydrocarbon-bearing zones of interest. The lower zone is perforated and stimulated if necessary. Thereafter, the tubular element is sealed with a plug which includes an explosive charge and the upper zone is fractured and stimulated. The explosive is then detonated thus severing the tubular element at the plug thereby permitting production of formation fluids from both zones into a common string of tubing.

Abstract: An oil or gas well is completed by cementing a casing string in a well having a special joint providing incipient perforations therein. The incipient perforations are closed during the cementing of the casing string in the well bore and are opened after the cement sets up. Preferably, the incipient perforations are opened concurrently with the fracturing of the cement sheath and the formation from which production is desired. The perforations of this invention are quite large and bear a ratio with the quantity of propellant in which there is at least 14 square inches of casing openings per cubic foot of propellant.

Abstract: A method of fracturing subsurface formations is provided which utilizes a mixture of a propellant and a propping agent. According to another aspect a mixture of a combustible material such as a propellant and a propping agent along with another composition which includes a combustible material are deposited in a borehole from a conduit system which is raised continuously through the borehole. After such deposition, the deposited compositions are ignited so as to cause fracturing of the formation around the borehole.

Abstract: The fixation of a packer or other borehole device is provided by explosively bonding the device to the borehole casing in the desired location. The explosively set packer is oriented in the borehole casing on a setting tool which preferably includes a casing scraper to clean the interior surface of the borehole casing, a removable packer to trap a gas pocket in the area where the explosive bonding is to occur and a gas transfer apparatus to form a gas pocket below the removable packer after the removable packer has been set.

Abstract: The effectiveness of controlled pulse fracturing treatment ("CPF") is enhanced by creating a foam when energy is released from the pulse device. Foam created by a foaming agent in the wellbore fluid increases said fluid's apparent viscosity and controls fluid loss. The increased viscosity causes additional fracture propagation. Upon commencement of production of hydrocarbonaceous fluids, fines and debris resultant from CPF are transported from the fractures which cleans up the well.

Abstract: A method for plugging a wellbore with a solid gel plug stem in high impulse or high energy fracturing. This method facilitates the removal of the propellant canister support means, the propellant ignition means, as well as any debris adhering thereto. By this method, damage to the wellbore and formation is minimized.

Abstract: The horizontal orientation of a rocket moving in a liquid is achieved by an arrangement in which a magnet is attached to the rocket body. The axis of the rocket and the magnetic axis of the magnet form an azimuthal angle .alpha., which determines the direction of the rocket relative to the geomagnetic meridian.

Abstract: A method for extending fractures in underground formations obtained by controlled pulse fracturing through the use of a stabilized hydrogen peroxide solution. Controlled pulse fracturing causes radial fracturing near the wellbore. These radial fractures are further extended into the formation or reservoir when stabilized hydrogen peroxide is forced into the radial fractures. Stabilizing agents in the hydrogen peroxide react with metals mixed with a proppant in the formation causing the hydrogen peroxide to breakdown and form gas pressure sufficient to extend the radial fractures. Hydrocarbonaceous fluids are then obtained from the natural fractures in said formation via the extended fractures which contact natural fractures emanating from the wellbore.

Abstract: A differential pressure actuated vent assembly is connected into an oil well tool string. In one form of the invention, the tool string includes a packer device, a perforating gun attached to the lower end of the tubing string, with the vent assembly being interposed between the gun and the packer device. Fluid pressure within the tubing string is effected on one face of a piston associated with the vent assembly, which reciprocates the piston and communicates the interior of the tubing string with the annulus around the tubing string while carrying out the step of perforating the formation. Movement of the piston and the subsequent detonation of the gun preferably are both accomplished sequentially in response to the dropping of a bar down through the tool string. The bar opens a passageway leading to the piston, and immediately thereafter, before the pressure differential between the interior of the tubing string and the annulus is equalized, the gun is detonated, thereby obviating damage to the formation.

Abstract: A method for extending fractures in underground formations obtained by controlled pulse fracturing through the use of stabilized hydrogen peroxide solution. Controlled pulse fracturing causes radial fracturing near the wellbore. In order to extend these radial fractures further into the formation or reservoir, stabilized hydrogen peroxide is forced into the radial fractures. Stabilizing agents in the hydrogen peroxide react with metals in the formation causing the hydrogen peroxide to breakdown and form gas pressure sufficient to extend the radial fractures. Hydrocarbonaceous fluids are then obtained from the formation via the extended fractures which contact natural fractures in the wellbore.

Abstract: An apparatus is provided for use in detonating explosives positioned in a well. The apparatus includes a first coupling member and a second coupling member. The first coupling member is joined to a housing containing explosives. Both the first coupling member and the second coupling member have conductor wire joined thereto. The first coupling member is hollow and of a size to matingly receive the second coupling member therein. Each coupling member is separately located near a desired location in the well. Then the coupling members are matingly joined together and electrical energy is delivered to the conductor wire of the second coupling member. By means of inductive coupling, electrical energy is provided to the conductor wire of the first coupling member. The electrical energy is used to detonate the explosives to produce a hole in a well casing at the desired location.

Abstract: A back-off tool comprising an explosive contained in a tubular housing which will disintegrate into fine particles upon detonation of the explosive. The explosive may be in the form of pellets so as to have the capability to vary the amount of explosive force by employing different diameter pellets and different numbers of pellets in the housing. A pressure compensation arrangement may be employed.

Abstract: A sonic fracing process and means to enhance production of oil and gas wells, increasing formation permeability by creating sonic waves that cracks and loosens the formation interstices. The sonic waves are created by a series of directed detonations and harmonic pulsations. The explosive material is placed inside the well bore and detonated from the surface. Two methods commonly used to increase formation permeability are known as Acidizing and/or Hydraulic Fracturing. The Sonic Frac has been designed to complement these fracing processes.Three inherent benefits are derived by using the Sonic Frac Process. First, and most important, is that the fine formation fissures are cracked and "opened" to allow flow of oil or gas to migrate from pores that would otherwise not be affected by conventional fracing processes. Second the pressure pulsations, which are created by the expansion of the gas utilized in conjunction with the Sonic cause the fluid in the wall bore to oscillate through the perforated zones.

Abstract: A method for creating a zone of increased permeability in a subterranean hydrocarbon-containing formation penetrated by a plurality of wellbores by penetrating the formation with a first wellbore; positioning a plurality of other wellbores about the first wellbore with each of the other wellbores having at least one substantially horizontal borehole extending therefrom into the vicinity of the first wellbore; extending a plurality of substantially horizontal boreholes from the first wellbore into the vicinity of the other wellbores; positioning explosive charges in at least a portion of the boreholes and detonating the explosive charges to produce a rubblized zone between the first wellbore and the other wellbores.

Abstract: A method for loading explosive charges into blastholes in a subterranean formation for forming a fragmented permeable mass of formation particles in an underground cavity in the formation is provided. Upper and lower voids spaced apart vertically from each other by unfragmented formation are excavated into the subterranean formation. A generally vertical blasthole is formed in the unfragmented formation between the voids. Upper and lower explosive charges, separated from one another by stemming, are formed in the blasthole. Each such explosive charge includes at least one primer operationally connected to an explosive initiating lead that extends from the charge. The explosive initiating lead of the upper explosive charge extends from the top of the blasthole into the upper void and the explosive initiating lead of the lower explosive charge extends from the bottom of the blasthole into the lower void.

Abstract: An apparatus for injecting a lubricating liquid, e.g., water, into a conduit as an annular layer around a flowing Bingham solid, e.g., a water gel or water-in-oil emulsion explosive, to facilitate the flow of the Bingham solid has an annular passageway from which the lubricating liquid flows into a cylindrical chamber containing the flowing Bingham solid. The annular passageway has a constricted throat portion of adjustable width, which, along with the flow rates of the Bingham solid and the lubricating liquid, is adjusted to produce a thin film of lubricant which allows lubricated plug flow of the Bingham solid in a descending section of conduit under the propelling force of gravity alone. Low drag permits the delivery of Bingham solid explosives into very deep vertical holes with no increase in the required pumping pressure.

Abstract: Electrohydraulic fracturing of rock and other dense materials is accomplished by coupling a hydraulic medium to the material to be fractured and inducing an explosive electrical discharge in the coupling medium in close proximity to the dense material thus developing an electrohydraulic shock wave in the coupling medium. This shock wave is transmitted into the rock or other dense material as an advancing compressive strain pulse which radiates from the explosive electrical discharge through the dense material until it is reflected by a free surface as a tensile strain pulse. The tensile strain pulse is impedance matched with the dense material to be fractured such that the tensile strain pulse induces in situ fracturing of the dense material. A motor driven generator system which provides alternating current to a control unit which incorporates a transformer and diode controlled bridge rectifier system providing stepped up DC voltage.

Abstract: A jar tool for use in a drill string for use in dislodging a drill bit or well-tools trapped in well bores. The tool comprises an outer housing adapted to move longitudinally with respect to an inner spline mandrell. A piston assembly is acted on by a piston actuator and hydraulic fluid restricts the movement of the piston assembly and, therefore, the movement of the mandrell relative to the housing, while the piston assembly is within a narrower portion of a hydraulic cylinder. When the piston assembly reaches a larger diameter portion of the cylinder, the hydraulic fluid rushes past the piston assembly which allows a knocker connected to the spline mandrell to collide with the outer housing. A compression spring returns the piston assembly to its rest position abutting a shoulder on the outer housing. Provision is made for pressure release values to be inserted in the piston assembly so that the tool can be operated within minimum and maximum operating limits.

Abstract: A process for gaining access to the coal of very deep seams, and for extracting this coal with the aid of a conveying liquid, which is fed to the seams via boreholes and is thence brought back again to the surface with coal which has been detached, wherein agents for detaching and breaking up the coal are admixed to the liquid.

Abstract: A method for initiating combustion in a subterranean carbonaceous deposit by positioning at least two wellbores from the surface into the subterranean deposit; extending a first borehole substantially horizontally from a first wellbore into the vicinity of a second wellbore; extending a second borehole substantially horizontally from a second wellbore into the vicinity of the first wellbore; positioning an explosive charge in at least one of the boreholes; detonating the explosive charge to produce a rubblized zone between the first wellbore and the second wellbore; injecting a free-oxygen containing gas into the carbonaceous deposit through one of the wellbores; and igniting the carbonaceous deposit at one of the wellbores.

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 process for enlarging or widening rock fractures in order to facilitate the recovery of deposits, such as oil or gas, comprising the emplacement of an aluminothermic mixture of aluminum and ferric oxide, and its subsequent ignition. Preferably, slag-forming products are also placed into the cavity, so as to prevent closure of the fractures after termination of the combustion process.

Abstract: A method for preventing annular fluid flow following primary cementing of oil and gas well casings is disclosed. Pursuant to said method the casing is vibrated so as to maintain the hydrostatic pressure of the cement column surrounding the casing at or above the pressure of the fluids in the various formations penetrated by the well until the cement has acquired its initial set. The vibration may be either continuous or intermittent. Preferably, the vibration has a low frequency. The method may include the additional step of applying pressure to the surface of the cemented annulus while the cement is curing. The vibration may be induced in several ways. For example, the casing may be vibrated by simultaneous or sequential explosions of a slow-burning black powder. Alternatively, hydraulic jars may be used to strike blows on the casing causing the casing to vibrate.

Abstract: An in situ leaching or solution mining process is conducted in a subterranean cavity in communication with a well bore. The subterranean cavity is gradually enlarged by inducing spallation of formation particles and/or collapse of the roof into the cavity by repeatedly cycling the hydraulic pressure in the subterranean cavity. The hydraulic pressure is preferably increased during a period of at least about two hours. The hydraulic pressure can be gradually decreased during a period of at least about two hours or can be suddenly decreased. Rapid pressure pulses can be applied to liquid in the subterranean cavity by detonation of shaped charges of explosive with the axis of force of the charge being directed along the axis of the well.