Abstract: Techniques for determining depths of provenance of drill cuttings contained in a drilling fluid received from a wellbore. The drilling fluid contains drill cuttings of different sizes that arrive at surface at different times, and the drill cuttings originate from different formation layers at different depths along the wellbore. Such techniques may include extracting samples of drill cuttings from the drilling fluid and repeating this step as necessary to provide samples of drill cuttings that arrive at surface at different recorded times; characterizing one or more formation attributes associated with the drill cuttings; and for each formation attribute, estimating a distribution of formation attribute characterization versus depth of provenance.

Abstract: Disclosed herein is a device and method for correlating core sample zones with an actual subterranean depth. The disclosed device has a pair of independent distance measuring devices operably in communication with a core sample apparatus where a first distance measuring device measures the length of a core sample entering a core sampling tube and a second distance measuring device measures a drive depth of the core sampling tube entering into the ground. A processing unit is provided for correlating the two distances so as to allow a determination as to the actual depth below ground from where a given zone of the core sample is extracted.

Abstract: A drilling dynamics data recorder is positioned within a slot in a downhole tool. The drilling dynamics data recorder may include a sensor package, the sensor package including one or more drilling dynamics sensors and a processor, the processor in data communication with the one or more drilling dynamics sensors. The drilling dynamics data recorder may also include a memory module, the memory module in data communication with the one or more drilling dynamics sensors and a communication port, the communication port in data communication with the memory module. The drilling dynamics data recorder may further include an electrical energy source, the electrical energy source in electrical communication with the memory module, the one or more drilling dynamics sensors, and the processor.

Abstract: A method includes taking at least one image of a plurality of returned cuttings from a well using a fluorescent imaging camera, analyzing the at least one image with an imaging processing system to obtain detection data including a calculated percentage of a first emitted fluorescent light to formation cuttings, sending the detection data to an analysis and control program to correlate the returned cuttings with a depth in the well, and automatically controlling at least one drilling parameter for drilling the well based on the detection data.

Abstract: Systems and methods to evaluate a formation by analyzing drill cuttings involve a multi-frequency dielectric coaxial probe to obtain a reflected voltage from a medium under test based on a reference voltage over a frequency range. The medium under test includes the drill cuttings. The system includes a processor to compute an effective permittivity of the drill cuttings over the frequency range based on a reflection coefficient, which is a ratio of the reflected voltage to the reference voltage over the frequency range, and to determine one or more parameters from the effective permittivity. The one or more parameters are used to make decisions about subsequent drilling in the formation.

Abstract: A system for monitoring the volume of cuttings exiting a shaker table is disclosed. The system comprises a shaker table configured to be adjusted based on information compiled by a processor and at least one camera configured to monitor said shaker table. The camera may be operably connected to the processor. The processor may be configured to identify drill cuttings and estimate the volume of the cuttings exiting the shaker table using machine vision techniques.

Abstract: A gas analysis system for determining the gas content of subterranean strata. A boring operation is commenced to form a borehole into or through a subterranean formation, such as a coal or shale formation to determine the gas content thereof. The drill fluid, cuttings and any desorbed gas is carried from the downhole location to surface analysing equipment in a closed system, so that the desorbed gases are not exposed to the air. The drill stem is capped or sealed at the surface, as well as the wellbore annulus to effectively seal the drill liquid, cuttings and desorbed gasses. The drill fluid, cuttings and desorbed gasses from the formation are coupled from the wellhead apparatus to the gas processing equipment via a closed system so that the constituents and volume of the gas can be determined.

Abstract: A coring apparatus may be integrated with fluid analysis capabilities for in situ analysis of core samples from a subterranean formation. An instrumented coring apparatus may include an inner core barrel; an outer core barrel; a coring bit; and an instrumented core barrel having an analysis device in fluid communication with the inner core barrel.

Abstract: In one aspect, an apparatus for use during drilling of a wellbore is provided, that in one embodiment may include: a receiving device that receives cuttings from the separator; a sensor for providing information relating to weight of the cuttings received by the receiving device for determining the weight of the cuttings received. In another aspect, a method of determining amount of cuttings received in a fluid from a wellbore is disclosed that in one embodiment may include: separating the cuttings from the fluid; receiving the separated cuttings on a member; determining weight of the cuttings received using a sensor associated with the receiving device.

Abstract: A coring apparatus is provided, which apparatus, in one exemplary embodiment, includes a rotatable member coupled to a drill bit configured to drill a core from a formation, a substantially non-rotatable member in the rotatable member configured to receive the core from the formation, and a sensor configured to provide signals relating to rotation between the rotatable member and the substantially non-rotatable member during drilling of the core from the formation, and a circuit configured to process the signals from the sensor to estimate rotation between the rotatable member and the non-rotatable member.

Abstract: Systems and methods for analysis of drilling cuttings are described. Complex permittivity is measured of rock cutting samples obtained during drilling operations. The origin of the cuttings is known by flow rate analysis in the drilling system. Various means can be used for rock cutting dielectric measurement. For example, the dielectric measurement can be made by matching the unknown permittivity of the medium to be analyzed to the permittivity of known liquid mixtures by successive saturation and looking for a “zero-contrast” measurement.

Abstract: A method for detecting hydrocarbon zones in a geological formation, including obtaining a plurality of pulverized drill cutting samples representative of the geological material encountered at measured depth intervals, each drill cutting obtained at periodic intervals during the drilling process; measuring each cutting sample with a color measuring device to obtain a value representing the degree of lightness of the particular cutting sample; and analyzing the measured lightness values by order of borehole depth that the respective cutting sample was obtained to determine the presence of geological zones likely to possess producible hydrocarbons. L* data may be combined with other well logging data to improve the hydrocarbon layer determination accuracy. A method also for locating the drill bit within a desired hydrocarbon layer during directional drilling.

Abstract: A system and method for solid-liquid separation and analysis of drilling fluids is described. The method includes heating a retort body to a pre-determined temperature, with an inner wall of the retort body at least partially defines a chamber within the retort body. A sample drilling fluid may be automatically injected into the inner chamber, and a film of the sample drilling fluid may be generated on the inner wall of the retort body. The film may be separated into a solid portion and a vapor. The method may further include collecting vapor using a vent that provides fluid communication with the inner chamber, and condensing the vapor into a fluid portion of the film. The volume of the fluid portion may them be automatically measured.

Abstract: In one aspect, the disclosure provides a method of drilling a wellbore, which method, in one embodiment, includes the features of drilling the wellbore with a drill string that includes a bypass device having a fluid passage therethrough by supplying a fluid through the bypass device, wherein the drilling fluid circulates to the surface via an annulus between the drill string and the wellbore; defining a time period (locking time); initiating a selected drilling parameter; detecting downhole the selected drilling parameter and one of the second flow rate and a differential pressure; and activating the bypass device when the selected drilling parameter and one of the second flow rate and the differential pressure are present during the defined time period to divert a portion of the drilling fluid from the bypass device to the annuls. In one aspect, the selected drilling parameter is rotation of a member associated with the bypass device.

Abstract: A method for detecting hydrocarbon zones in a geological formation, including obtaining a plurality of pulverized drill cutting samples representative of the geological material encountered at measured depth intervals, each drill cutting obtained at periodic intervals during the drilling process; measuring each cutting sample with a color measuring device to obtain a value representing the degree of lightness of the particular cutting sample; and analyzing the measured lightness values by order of borehole depth that the respective cutting sample was obtained to determine the presence of geological zones likely to possess producible hydrocarbons. L* data may be combined with other well logging data to improve the hydrocarbon layer determination accuracy. A method also for locating the drill bit within a desired hydrocarbon layer during directional drilling.

Abstract: Systems and methods for analysis of drilling cuttings are described. Complex permittivity is measured of rock cutting samples obtained during drilling operations. The origin of the cuttings is known by flow rate analysis in the drilling system. Various means can be used for rock cutting dielectric measurement. For example, the dielectric measurement can be made by matching the unknown permittivity of the medium to be analyzed to the permittivity of known liquid mixtures by successive saturation and looking for a “zero-contrast” measurement.

Abstract: A system for slurrifying drill cuttings including a cuttings dryer, a pump, and a transfer line fluidly connecting the cuttings dryer and the pump, the transfer line having a fluid inlet for receiving a fluid. Furthermore, the system for slurrifying drill cuttings including a storage vessel fluidly connected to the pump for storing a slurry. Additionally, a method for slurrifying drill cuttings including drying drill cuttings in a cuttings drying to produce dry cuttings and combining a fluid with the dry cuttings to produce a slurry. Furthermore, the method includes mixing the slurry and the dry cuttings in a mixing pump and transferring the slurry to a storage vessel.

Abstract: A system and method for detecting a cuttings bed that includes a drill bit, a drillstring and a cuttings bed detector. The cuttings bed detector is positioned uphole of the drill bit. The method includes the steps of positioning a drill bit downhole, and positioning a cuttings bed detector uphole of the drill bit.

Abstract: A system for slurrifying drill cuttings including a cuttings dryer, a pump, and a transfer line fluidly connecting the cuttings dryer and the pump, the transfer line having a fluid inlet for receiving a fluid. Furthermore, the system for slurrifying drill cuttings including a storage vessel fluidly connected to the pump for storing a slurry. Additionally, a method for slurrifying drill cuttings including drying drill cuttings in a cuttings drying to produce dry cuttings and combining a fluid with the dry cuttings to produce a slurry. Furthermore, the method includes mixing the slurry and the dry cuttings in a mixing pump and transferring the slurry to a storage vessel.

Abstract: An apparatus and method for analyzing the continuous flow of drilling cuttings in real time on a surface while drilling employs a set of sensors placed around an analyzer tube and main auger or within the main auger related to the formation with a defined space-time shift. The method includes measuring the sample to obtain specific properties related to physical and petrophysical parameters of this formation (radiation, resistivity, inductivity, density, elasticity, others). Obtained signals are conditioned and digitized in order to derive the desired discrimination in target properties, such as rock type, porosity, density, and oil saturation. An expanding auger, with a hollow end adapted to receive a sensor tube in which the sensors or sources may be placed, is adapted to rotate or circulate a discrete media about the sensors.

Abstract: A system for determining produced drill solids volume including a receiving vessel for receiving drill solids and a pressure vessel coupled to the receiving vessel. The receiving vessel has an isolation valve system to control the flow of drill solids between the receiving vessel and the pressure vessel, and the pressure vessel is adapted to allow a compressed gas to convey drill solids from the pressure vessel to a discharge line. The system also includes a skid having a plurality of weight sensors for weighing the drill solids in the pressure vessel, wherein the pressure vessel is disposed on the plurality of weight sensors and a programmable logic controller operatively couples to at least the plurality of weight sensors for calculating the weight of the drill solids in the pressure vessel.

Abstract: Systems and methods are described for detection and removal of underground organic and inorganic compounds utilizing underground boring tool technology. Typically a drilling fluid is flowed through a pipe or drill string, over the boring tool, and back up the bore hole to the surface in order to remove cuttings and dirt at the surface. Solids and liquids discharged at the surface are analyzed real-time to determine concentrations and locations of compounds in the subsurface and determine the geology of the formation. Detectors can also be attached directly to the head of the boring apparatus and data transmitted to the surface electronically or by other means. Data is processed and evaluated. Based on this information, the boring tool is continually re-directed along an underground path to the areas with the highest concentrations of minerals, oil, gas, toxic compounds or other elements or compounds of interest.

Abstract: A new method for evaluating the efficiency of a sweep for removing cuttings from a borehole in a subterranean formation during a drilling operation. The method evaluates sweep efficiency on a “mass” in versus “mass out” basis. The method uses downhole density readings taken with a pressure-while-drilling tool inserted in the drill string. Measurements of hydrostatic pressure are converted into equivalent circulating density measurements which in turn are used in calculating the sweep efficiency. The method affords real time estimates at the wellsite of the quantity of formation cuttings brought out of a wellbore by a sweep.

Abstract: A new method for evaluating the efficiency of a sweep for removing cuttings from a borehole in a subterranean formation during a drilling operation. The method evaluates sweep efficiency on a “mass in” versus “mass out” basis. The method uses downhole density readings taken with a pressure-while-drilling tool inserted in the drill string. Measurements of hydrostatic pressure are converted into equivalent circulating density measurements which in turn are used in calculating the sweep efficiency. The method affords real time estimates at the wellsite of the quantity of formation cuttings brought out of a wellbore by a sweep.

Abstract: A system of apparatus for use in a coring tool measures the height of a core sample being recovered and transmits data relative thereto to the surface of a formation concurrently during the coring operation. A transmitter of an electromagnetic ranging system rides atop a core sample being formed in the barrel chamber and a receiver member of the electromagnetic ranging system is fixed at a top end of the barrel it known distance above the transmitter. During the coring operation the transmitter transmits a fixed frequency signal to the receiver through drilling fluid disposed therebetween. The distance between the transmitter and receiver decreases and the amplitude of the transmitted signal changes as a function of the separation distance between the transmitter and receiver as the core sample enters the inner barrel and the height of the core sample within the barrel is determined as a function of time and depth.

Abstract: A method and apparatus for retrieving magnetic casing fragments from a well using a shrouded magnet are disclosed. Retrieving casing fragments allows the determination of weight loss from the casing to assist in analyzing the integrity and the condition of the casing and to determine whether more expensive analysis is required. The shrouded magnet, that is formed by a non-magnetic container enclosing a source of magnetic field, recovers metal casing fragments by attracting them and other magnetic materials from oil and gas well fluids passing by the shrouded magnet device, which fragments are easily separated from the device by removing the source of magnetic field from the container.

Abstract: System of evaluating physical parameters such as the absolute permeability of porous rocks of a zone of an underground reservoir, from fragments taken from this zone, such as rock cuttings carried along by the drilling mud. Rock fragments (F) are immersed in a viscous fluid contained in a vessel (1). Pumping means (2, 3) first inject into vessel (1) a fluid under a pressure that increases with time, up to a determined pressure threshold, so as to compress the gas trapped in the pores of the rock. This injection stage is followed by a relaxation stage with injection stop. The pressure variation measured by detectors (7, 8) during these two successive stages is recorded by a computer (9). The evolution of the pressure during the injection process being modelled from initial values selected for the physical parameters of the fragments, the computer adjusts them iteratively so as to best get the modelled pressure curve to coincide with the pressure curve really measured. Application: petrophysical measurement.

Abstract: A method and apparatus for perforating and stimulating a subterranean formation which is penetrated by a well bore having casing positioned therein so as to establish fluid communication between the formation and the well bore. Substantially rigid, flexible, or liquid propellant is interposed between the casing and at least one shaped charge in a subterranean well bore and is ignited due to the shock, heat and/or pressure generated from the detonated charge. Upon burning, the propellant material generates gases which clean perforations formed in the formation by detonation of the shaped charge(s) and which extend fluid communication between the formation and the well bore.

Abstract: An apparatus for use in a subterranean well includes a downhole energy source, a first switch, a second switch, a detonator, a first controller and a second controller. The first switch has a first predetermined state to transfer energy from the energy source, and the second switch has a second predetermined state to transfer the energy from the energy source. A detonator receives the energy from the energy source when the first switch and second switches are concurrently in the first and second predetermined states. A first controller independently detects a predetermined stimulus that is transmitted from the surface of the well and causes the first switch to enter to first predetermined state based on the detection by the first controller. A second controller independently detects the predetermined stimulus transmitted from the surface of the well and causes the second switch to enter the second predetermined state based on the detection by the second controller.

Abstract: A perforating gun for perforating a section of a well casing in which a plurality of explosive charge units are mounted on an elongated mounting strip in a pattern corresponding to the desired pattern of perforations in the well casing. The areas of the mounting strip that receive the charge units have a greater width than the remaining areas of the strip to provide an increased support surface for the charge units. Each charge unit is formed by a case connected to a cap to provide a housing for the explosive. The cap is crimped to the case to prevent premature detonation of the explosive.

Abstract: A tubing conveyed perforating apparatus is shown which includes a tubular assembly made up of a plurality of tubular sections. A plurality of explosive charges are located within the interior bore of at least two of the tubular sections of the tubular assembly. A firing head is carried on the tubular assembly for detonating the explosive charges to perforate a surrounding well bore. The firing head has a concentric detonator arrangement within a hollow central bore. The explosive charges are held within the interior bore of the tubular section by a support. The explosive charges and charge support are comprised of materials which disintegrate upon detonation of the explosive charges, whereby the interior bore of the tubular assembly is fully open after detonation.

Abstract: Rock and other hard materials, such as concrete, are fragmented by a controlled small-charge blasting process. A cartridge containing an explosive charge is inserted at the bottom of a hole drilled in the rock. The explosive charge is configured to provide the desired pressure in the hole bottom, including, if desired, a strong shock spike at the hole bottom to enhance microfracturing. The cartridge is held in place or stemmed by a massive stemming bar of high-strength material such as steel which blocks the flow of gas up the drill hole except for a small leak path between the stemming bar and the drill hole walls. The cartridge-incorporates additional internal volume designed to control the application of pressure in the bottom hole volume by the detonating explosive.

Abstract: An improved downhole explosive charge carrier is disclosed. The invention uses a unique staggered charge pattern and a mounting configuration which allows the use of a straight, axially-located detonator in order to achieve a greater number of shots per unit length over conventional carriers. The invention also reduces the interference caused by the detonator and the closeness of the shots and thereby increases the performance of the individual charges, allowing smaller charges to be used to achieve the same perforation size.

Abstract: The invention is directed to an expendable tubing conveyed perforator, comprising (a) an outer tube made from a material having high strength and low impact resistance; and (b) an inner structure positioned within the outer tube for holding one or more explosive charges, the inner structure made from a combustible material. The invention is also directed to a method of perforating a well casing using the expendable tubing conveyed perforator system.

Abstract: Methods and apparatus for creating as shear ("S") wave for use in oil and gas exploration, where such S-wave is created by detonating an explosive packaging in a shot hole in a manner that produces directionally controlled S-wave force vectors at each source station across a 3-D survey grid.

Abstract: A tubing conveyed perforating apparatus is shown which includes a tubular assembly made up of a plurality of tubular sections. One or more elongate charge holders are located within the interior bore of the tubular assembly and carry explosive charges thereon. A firing head is carried on the tubular assembly for detonating the explosive charges to perforate a surrounding well bore. The charge holders and explosive charges are comprised of materials which disintegrate upon detonation of the explosive charges, whereby the interior bore of the tubular assembly is fully open after detonation.

Abstract: A perforating gun having a base structure made of a deformable material. The base structure includes support rings integrally attached to one another by connector portions. The capsule charges are mounted in corresponding support rings, and each support ring is adjustable by selective deformation of the base structure to face in one of a plurality of directions to provide a plurality of combinations of phasing patterns.

Abstract: A flexible linear shaped charge for discharging a high speed jet to penetrate a target comprising an outer housing which includes a sheath and the high speed jet, the high speed jet being integral with the sheath, and an explosive core disposed within the outer housing between the sheath and the high speed jet, the outer housing comprising a low density matrix mixed with a high density heavy metal powder to increase the confinement of the explosive core, thereby improving the performance of the shaped charge.

Abstract: A shaped charge and liner having a minimum outside diameter determined by the formula:D.sub.L =2.625-0.3571(6 -D.sub.ID)Where:D.sub.L =Liner Minimum Outside DiameterD.sub.ID =Carrier Inside DiameterThe geometry of the shaped charge reduces the chances of interference between charges by controlling burn time, as does the positioning of the primer cord. The liner has an open end with a minimum outside diameter determined by the formula. The shape of the case and liner is determined by keeping the center of the primer cord a distance not greater than 0.10 (D.sub.ID) from the center line of the carrier, ideally not greater than 0.05 (D.sub.ID). This yields a large diameter, flat shaped charge that may be loaded in a tubular carrier having a charge or perforation density of at least 10 shots per foot.

Abstract: A high density perforating gun having a carrier housing tube and an interior charge holder tube through which are mounted zinc alloy shaped charges in a phased relationship between about 135 and 145 degrees. The 135 to 145 degree phased relationship provides for an 18 shot per foot perforating gun system. The shaped charges of selected length are inserted into the carrier housing tube and held in place by fastener rings fitted to fastener ring slots. The nose ends of the shaped charges are fitted with ears to receive a detonating cord. This positions the primer cord in tension and generally coaxially with the carrier housing tube to prevent charge interference and assure sequential detonation.

Abstract: A borehole drilling apparatus has a jacket attachable to a well head and through which a drill rod passes and which carries pressurized drilling fluid to a working end of the drill rod and out into an annulus of the borehole. The jacket has a drill rod seal and an outlet port leading from the interior of the jacket to a pressure regulator. The pressure regulator comprises an annular space through which fluid can flow from an inlet to an outlet. The annular space is defined between an inner rod and a surrounding elastomer pipe. In use, the elastomer pipe is squeezed radially inwards toward the inner rod by fluid pressure maintained between the outside of the elastomer pipe and a surrounding housing. A sampling system is in communication with the outlet port at a location upstream of the regulator.

Abstract: A method and apparatus for perforating and stimulating a subterranean formation which is penetrated by a well bore having casing positioned therein so as to establish fluid communication between the formation and the well bore. A shell, sheath or sleeve of propellant material is positioned so as to substantially encircling at least one shaped charge in a subterranean well bore and is ignited due to the shock, heat and/or pressure generated from the detonated charge. Upon burning, the propellant material generates gases which clean perforations formed in the formation by detonation of the shaped charge(s) and which extend fluid communication between the formation and the well bore.

Abstract: The invention relates to an explosive charge assembly for cutting tubular members, particularly underwater. The assembly is lowered into the tubular member to a distance where the cut is to be performed. A shaped charge carrier has a pair of parallel circular plates, a casing unitary connected to the plates and a truncated shaped charge liner. An inflatable bladder surrounding the casing expands to create a stand off distance between the wall of the tubular member and the shell of the assembly. A plurality of centralizer members allow to adjust position of the shell in the tubular member prior to detonation.

Abstract: A through-tubing perforating gun and method is provided. The assembly comprises an elongated carrier strip, a plurality of perforating charges, and means for connecting the plurality of charges to the carrier strip. Each of the charges has a focal axis along which a shaped charge explosion occurs in a firing direction when the charge is actuated for use in perforating the casing wall, a cross-section that fits within a circle defined by the smallest inner diameter of the well tubing through which the assembly is intended to pass, and a detonating cord receiving means.

Abstract: A penetrating bomb weapon comprising a long hollow cylinder constructed of high strength steel or similar material and including a pointed nose to aid in penetration of media such as concrete, soil, steel or a hardened surface. The cylinder contains an insensitive explosive that is separated into segments by shock attenuating materials so that one segment of the cylinder may detonate without detonating or destroying adjacent segments. The number of segments may be two or more depending on the complexity of the target to be attacked. Initiation of the main charge within each segment is achieved using explosive boosters positioned so that shocks transferred to adjacent segments, and the initiation train of these segments, is minimized. Separation of the segments is accomplished using explosive cutter charges which perforate and/or spall through the case wall of the penetrator bomb.

Abstract: A perforating gun includes a multiplicity of shaped charges, the multiplicity of shaped charges including a plurality of planes of charges, each plane of charges including a plurality (N) of shaped charges and a detonating cord running down through the axial center of each of the plurality of planes of charges. The plurality (N) of shaped charges are equally spaced at an angle 360/N about the detonating cord. The plurality of planes of charges: (1) are rotated at an angle of 180/N relative to one another, and (2) are axially packed together along the longitudinal axis of the gun so that the charges in one plane are nearly touching the charges in the adjacent plane, yet they all share the same centered detonating cord. The proximity of one plane to another is close enough such that one plane of charges detonates within a few microseconds of its neighboring plane of charges.

Abstract: A perforating gun having an elongated mounting strip and a selected wave or non-linear, zig-zag form as seen in a plan view, with an outer surface diameter sized for convenient insertion and removal from a well. The mounting strip has a series of openings spaced in intervals for mounting capsule explosive charges in a phased relationship between 0 and 360 degrees. The cross-sectional area of the mounting strip around each opening is selected to prevent fragmentation of the carrier upon detonation of the charges. The mounting strip is preferably metallic with a selected amplitude and wave length. In each opening is an explosive capsule with a hollow cap with a nose for attachment to one of the openings. The cap has an annular, interior thread with a thread run-out of selected width.

Abstract: This invention is in the field of perforating gun systems used, for example, to gain access to underground oil and gas formations. In particular, this invention relates to an expendable holder assembly for shaped charges of such systems.

Abstract: A perforating gun having an elongated, spiral strip with an outer surface, cylindrical about a longitudinal axis, and a diameter sized for convenient entry and removal from a well. The strip has a series of threaded openings spaced in intervals for mounting capsule explosive charges in a phased relationship between 0 and 360 degrees. The cross-sectional area of the strip around each opening is selected to prevent fragmentation of the carrier upon detonation of the charges. The spiral strip is preferably metallic and forms a helical band with a pitch in a range of 12 to 24 inches. In each threaded opening is an explosive capsule with a hollow cap having at one end a threaded nose for attachment to one of the threaded openings. The cap has an annular, interior thread with a thread run-out of selected width at the other end.

Abstract: An improved capsule-type charge for use in perforating high temperature production zones in oil or gas wells is disclosed. The improvement consists of using a secondary initiating compound as an initiator, such as 1,3,5-Trinitro-2,4,6-Tripicrylbenzene or 2,2',2",4,4',4",6,6',6",-Nonanitroterphenyl. These initiators work well with commercially available high temperature explosives, such as PYX.