Abstract: A method for small-charge blasting, and a rock drilling unit used therein. By means of a rock drilling machine of the rock drilling unit, a drill hole is first drilled into material to be excavated, after which one or more cartridges comprising a propellant charge are fed through a drilling tool onto the bottom of the drill hole. The drilling unit comprises a cartridge feed station, which is separate from the rock drilling machine and from which the cartridges may be fed into a longitudinal channel in the drilling tool.

Abstract: An apparatus for use in deployment of downhole tools is disclosed. Preferably, the apparatus includes at least an in-ground well casing, a housing providing a hermetically sealed electronics compartment, a tool attachment portion, and a first flow through core. The housing is preferably configured for sliding communication with the well casing. The hermetically sealed electronics compartment secures a processor and a location sensing system, which communicates with the processor while interacting exclusively with features of the well casing to determine the location of the housing within the well casing. A preferred embodiment further includes a well plug affixed to the tool attachment portion, the well plug includes a second flow through core capped with a core plug with a core plug release mechanism, which upon activation provides separation between the second flow through core and the core plug, allowing material to flow through said first and second flow through cores.

Abstract: A method of mitigating perforating effects produced by well perforating can include causing a shock model to predict perforating effects for a proposed perforating string, optimizing a compliance curve of at least one proposed coupler, thereby mitigating the perforating effects for the proposed perforating string, and providing at least one actual coupler having substantially the same compliance curve as the proposed coupler. A well system can comprise a perforating string including at least one perforating gun and multiple couplers, each of the couplers having a compliance curve, and at least two of the compliance curves being different from each other. A method of mitigating perforating effects produced by well perforating can include interconnecting multiple couplers spaced apart in a perforating string, each of the couplers having a compliance curve, and selecting the compliance curves based on predictions by a shock model of shock generated by the perforating string.

Abstract: A shock de-coupler for use with a perforating string can include perforating string connectors at opposite ends of the de-coupler, a longitudinal axis extending between the connectors, and a biasing device which resists displacement of one connector relative to the other connector in both opposite directions along the longitudinal axis, whereby the first connector is biased toward a predetermined position relative to the second connector. A perforating string can include a shock de-coupler interconnected longitudinally between components of the perforating string, with the shock de-coupler variably resisting displacement of one component away from a predetermined position relative to the other component in each longitudinal direction, and in which a compliance of the shock de-coupler substantially decreases in response to displacement of the first component a predetermined distance away from the predetermined position relative to the second component.

Abstract: A bending shock de-coupler for use with a perforating string can include perforating string connectors at opposite ends of the de-coupler. A bending compliance of the de-coupler may substantially increase between the connectors. A well system can include a perforating string including at least one perforating gun and multiple bending shock de-couplers, each of the de-couplers having a bending compliance, and at least two of the bending compliances being different from each other. A perforating string can include a bending shock de-coupler interconnected longitudinally between two components of the perforating string. A bending compliance of the bending shock de-coupler may substantially decrease in response to angular displacement of one of the components a predetermined amount relative to the other component.

Abstract: Methods for evaluating drill pattern parameters such as burden, spacing, borehole diameter, etc., at a blast site are disclosed. One method involves accumulating the burden contributed by successive layers of rock and matching the accumulated rock burden to a target value for a borehole having a length related to the average height of the layers. Another method relates to varying drill pattern parameters and characteristics to match blast design constraints, including the substitution of one explosive material for another by the proper balance of materials and/or output energies to the associated rock burden. Analysis of deviations from target rock burdens and corrective measures are disclosed, as well as cost optimization methods. The various methods can be practiced using an appropriately programmed general purpose computer.

Abstract: A rock breaking cartridge in which an energetic composition is ignited by an actuator which acts on a primer through the medium of water in a confined volume between the actuator and the primer.

Abstract: A perforating apparatus that is usable with a well includes a shaped charge. The shaped charge includes a case, an explosive and a liner. The liner is adapted to form a perforation jet to form a perforation tunnel and promote an exothermic reaction inside the tunnel to create a pressure wave to force debris from the tunnel.

Abstract: Application of the method and device to a water well will permanently seal the well casing in order to prevent hydraulic cross-contamination with other water wells in the area. The method employs a string to explosive modules in spaced relation along the depth of a well casing. This weighted string of explosive modules is lowered into the well casing, wet concrete should then be introduced into the casing, after which the explosive elements are detonated sequentially, starting at the top of the well. Detonation of the elements in such a manner should force the wet concrete or cement out through the well casing perforations, so that the well casing will be entirely captured within the cured concrete. The individual explosive elements are made from detonating cord and metallic ball bearings wrapped into bundles, and then the bundles are bound in suitable adhesive tape.

Abstract: Methods, systems, and apparatus that are suitable for use in production of hydrocarbons from subterranean heavy oil deposits employ a subterranean cavity in communication with a borehole. The cavity is preferably formed along a U-tube borehole by coiled tubing reaming operations and/or radial drilling and explosive blasting.

Abstract: A perforating apparatus (50) includes a carrier gun body (52) having a plurality of radially reduced sections (54). The radially reduced sections (54) have a nanocomposite outer layer (72). A charge holder (62) is positioned within the carrier gun body (52). A plurality of shaped charges (56) are supported by the charge holder (62). The shaped charges (56) each have an initiation end and a discharge end. The discharge ends of the shaped charges (56) are disposed proximate the radially reduced sections (54) of the carrier gun body (52) such that the jets formed upon detonation of the shaped charges (56) travel through the radially reduced sections (54). The nanocomposite outer layers (72) of the radially reduced sections (54) enable enhanced performance of the perforating apparatus (50) in high pressure and high temperature wellbores.

Abstract: A method for small-charge blasting, and a rock drilling unit used therein. By means of a rock drilling machine of the rock drilling unit, a drill hole is first drilled into material to be excavated, after which one or more cartridges comprising a propellant charge are fed through a drilling tool onto the bottom of the drill hole. The drilling unit comprises a cartridge feed station, which is separate from the rock drilling machine and from which the cartridges may be fed into a longitudinal channel in the drilling tool.

Abstract: A perforating system having a perforating gun with a pressurizable gun body. The gun body can be pressurized prior to deployment in a wellbore, or while in the wellbore. Pressurizing the gun body can include adding fluid into the gun body, such as a pressurized gas, a liquid, or combustion products. A seal diaphragm can be used to transfer wellbore pressure into the gun body.

Abstract: The invention relates to a method for completing a borehole (1, 2) prior to the start of production, wherein after making the borehole (1, 2) the borehole wall (3) is anchored in a sealed manner with a conveying tube (4) and/or casing tube, and the borehole wall (3) is perforated with perforation units (5) at desired points. To complete a borehole without the use of cemented conveying tubes and/or casing tubes, it is proposed that the conveying tube (3) and/or casing tube be provided on its outer surface with a swellable sealing jacket (6), wherein the sealing jacket (6) swells after activation and anchors the annular gap between the conveying tube (4) and/or casing tube and the borehole wall (3) in a sealed manner and simultaneously centres the conveying tube (4) and/or casing tube in the borehole (1, 2).

Abstract: The scales that allow for the shear planes (first scale), the rock and/or crust geometry (second scale), and the change of the geometries as earthquake systematics (third scale) are the basis for prediction and reduction of intensity. Actions to generate mini-movements to reduce the intensity of earthquakes are then concentrated on those areas where the stress concentrations generate jerky movements to alter the rock geometry (third scale). Based on the scale, the large-scale areas that influence the local stress concentrations and are involved in the jerky movements are thus taken into consideration.

Abstract: Pressure cycle operated apparatus and methods. A method of actuating a firing head includes the steps of: reciprocably displacing an actuator piston of the firing head, the displacing step including the piston being alternately pressure balanced and unbalanced; and igniting a combustible material in response to the piston displacing step. A method of generating electricity includes: reciprocably displacing a piston, the displacing step including the piston being alternately pressure balanced and unbalanced; and generating electricity in response to the piston displacing step. A firing head includes an actuator piston separating at least two chambers; a check valve which permits one-way flow between the chambers; a flow restrictor which restricts flow between the chambers; a biasing device which biases the piston toward one of the chambers; and a firing pin releasing device which releases a firing pin in response to displacement of the piston.

Abstract: A wellbore tool string includes a perforating gun having a plurality of explosive perforating charges and a shock mitigation tool. The shock mitigation tool including a tubular body having a top end, a bottom end, and a chamber; a barrier disposed proximate the bottom end in communication with the chamber; and a plurality of actuators connected with the body proximate to the top end of the body, each actuator opening a port in the body providing fluid communication with the chamber when the plurality of actuators are activated.

Abstract: A wellbore tool includes a perforating charge adapted to create a tunnel in a subterranean formation upon activation; a propellant that provides a pressure cycle when activated; and a delay device operationally connected to the perforating charge and the propellant to activate the perforating charge and the propellant in a manner to influence a selected wellbore condition.

Abstract: A system for verifying perforating gun status prior to perforating a wellbore. The system includes a perforating gun (38) having a leak sensor disposed therein that is positionable at a target location within the wellbore on a tubing string (30). A communication system (42, 44, 46, 48, 50) is integrated with the tubing string (30). The communication system (42, 44, 46, 48, 50) is operable to communicate with the leak sensor. A surface controller (40) is operable to send a first telemetry signal via the communication system (42, 44, 46, 48, 50) to interrogate the leak sensor regarding a leak status of the perforating gun (38), receive a second telemetry signal from the leak sensor via the communication system (42, 44, 46, 48, 50) including the leak status of the perforating gun (38) and determine whether to operate the perforating gun (38) based upon the leak status information.

Abstract: By using reactive shaped charges, a dynamic underbalance effect associated with detonation of a perforating system is enhanced without compromising shot density. Fewer shaped charges can be loaded to achieve the same or better effective shot density as a gun fully loaded with conventional shaped charges, thereby increasing the free volume within the gun while creating debris-free tunnels with fractured tips and substantially eliminating the crushed zone surrounding each perforated tunnel. Further, the strength and grade of gun steel required to construct the gun can be reduced without compromising the amount the gun swells following detonation.

Abstract: An oil and gas well shaped charge perforator capable of providing an exothermic reaction after detonation is provided, comprising a housing, a high explosive, and a reactive liner where the high explosive is positioned between the reactive liner and the housing. The reactive liner is produced from a composition which is capable of sustaining an exothermic reaction during the formation of the cutting jet. The composition may be selected from any known formulation which is suitable for use in an oil and gas well perforator, typically the composition will comprise at least two metals such as to form a inter-metallic as classified by Hume-Rothery electron compounds and at least one further metal, which is not capable of an exothermic reaction with the reactive composition which is present in an amount greater than 10% w/w of the liner. Typically at least one of the metals which undergoes an exothermic reaction may be selected from Al, Ce, Li, Mg, Mo, Ni, Fe, Co, Nb, Pb, Pd, Ta, Ti, Zn or Zr.

Abstract: The perforation gun is comprised of a tubular carrier, a charge holder, a plurality of sealed charges, and a detonating cord. The tubular carrier has a length and a plurality of openings. The charge holder has a length and is comprised of a plurality of mounting locations which are each capable of receiving one of the sealed charges. The charge holder is capable of being secured within the carrier. The detonating cord is coupled to at least one sealed charge. In the mounted position and when the charge holder is secured within the carrier, the charges are aligned with the openings in the carrier such that, upon detonation, charge blasts emitted from the charges exit though the carrier openings and perforate a well casing and cement. In one aspect of the invention, the carrier openings are spirally arranged and spaced along the length of the carrier. In still another aspect of the invention, the openings are vertically arranged and spaced along the length of the carrier.

Abstract: A device for perforating and fracturing a formation in a single trip includes shaped charges and a volume of a gas generator. When activated by detonation of the shaped charges, the gas generator forms a high-pressure gas, which includes steam, that expands to stress and fracture the formation. Suitable gas generating materials include hydrates and hydroxides. Other materials that can be employed with the gas generator include oxidizers and material such as metals that increase the available heat for the activation of the gas generator.

Abstract: Methods, systems, and apparatus that are suitable for use in production of hydrocarbons from subterranean heavy oil deposits employ a subterranean cavity in communication with a borehole. The cavity is preferably formed along a U-tube borehole by coiled tubing reaming operations and/or radial drilling and explosive blasting.

Abstract: A perforating gun train for perforating two or more zones of interest includes two or more gun sets made up of guns, one or more activators, and other associated equipment. An illustrative apparatus may include a first perforating gun; an activator responsive to the firing of the first perforating gun and a fuse element detonated by the activator; and a second perforating gun that is fired by the fuse element. An illustrative method for perforating a subterranean formation may include forming a perforating gun train using at least a first perforating gun and a second perforating gun; and energetically coupling the first perforating gun and the second perforating gun with an activator.

Abstract: A buffering device for use in conjunction with a downhole tool string, wherein the tool string includes a ballistics device. The buffering device includes a mandrel attached within a tool string and proximate to the ballistics device. An anchor is disposed on the mandrel and a disk plate is coaxially placed on the mandrel that is slideable thereon. The disk plate is proximate to the ballistic device. A resilient member, such as a spring, is coaxially placed on the mandrel between the disk plate and the anchor. The pressure wave produced by activation of the ballistic device pushes the disk plate toward the anchor and compresses the spring there between. Since the disk plate extends outward into sealing contact with casing lining the wellbore, compression of the spring dissipates energy waves produced by activation of the ballistic device.

Abstract: A method for perforating a subterranean formation includes positioning a shaped charge and a reactant composite material in a carrier; positioning the carrier in the wellbore; detonating the shaped charge; and disintegrating the reactant composite material using a shock generated by the detonated shaped charge. The method may also include initiating a first deflagration by using carbon and heat resulting from the detonation of the shaped charge and an oxygen component of the disintegrated reactant composite material. A system for performing the method may include a carrier, a shaped charge positioned in the carrier; and a reactant composite material positioned in the carrier. The reactant composite material may be configured to disintegrate upon detonation of the shaped charge.

Abstract: The invention provides a method for perforating a well with a perforating fluid comprising a viscoelastic surfactant that essentially stops fluid leak-off after perforation in an overbalanced condition. Another aspect of the invention provides the perforating fluid in itself. The well has a wellbore defined by a generally cylindrical casing in at least a portion of the wellbore (i.e., the wellbore is cased, although it is not necessary cased in its entire length). The wellbore passes through a subterranean formation that comprises hydrocarbon formation fluids (such as oil and/or gas), at least in certain strata. The method comprises placing a perforating device in a wellbore which includes at least one explosive perforating charge that can be detonated in order to perforate the casing and allow the formation fluids to enter the wellbore. The casing is located between the subterranean formation and the perforating device.

Abstract: Methods, systems, and apparatus that are suitable for use in production of hydrocarbons from subterranean heavy oil deposits employ a subterranean cavity in communication with a borehole.

Abstract: Disclosed is a device and method for externally perforating a well-bore casing. The perforating apparatus is attached to the outside of the casing itself and is conveyed along with the casing when it is inserted into the well bore. The perforation is accomplished using two groups of charges which are contained in protective pressure chambers which are arranged radially around the outside of the wellbore casing. The pressure chambers form longitudinally extending ribs which conveniently serve to center the casing within the well bore. One group of charges is aimed inward in order to perforate the casing. A second group is aimed outward in order to perforate the formation. In an alternative embodiment, only one group of bi-directional charges is provided.

Abstract: Disclosed is a device and method for externally perforating a well-bore casing. The perforating apparatus is attached to the outside of the casing itself and is conveyed along with the casing when it is inserted into the well bore. The perforation is accomplished using two groups of charges which are contained in protective pressure chambers which are arranged radially around the outside of the wellbore casing. The pressure chambers form longitudinally extending ribs which conveniently serve to center the casing within the well bore. One group of charges is aimed inward in order to perforate the casing. A second group is aimed outward in order to perforate the formation. In an alternative embodiment, only one group of bi-directional charges is provided.

Abstract: Embodied herein is a perforating gun wall that withstands short, high energy pulses of an explosion retained within a loading tube with numerous explosive shaped charges. The perforating gun wall includes two or more layers with an impact strength sufficient to maintain the structural integrity of the gun wall without splitting due to the explosion. Each layer is sleeved within the preceding layer forming a sleeved assembly. One or more of the inner layers includes one or more holes aligned with one or more explosive shaped charges. Each layer comprise a defined material property that reduces occurrences of catastrophic failure.

Abstract: An apparatus for reducing the post-detonation pressure of a perforating gun, the apparatus including a perforating gun carrying at least one explosive charge, wherein when the explosive charge is detonated the explosive charge produces a pressurized detonation gas, and a mechanism for reducing the pressure of the detonation gas proximate the perforating gun. The detonation gas pressure is desirably reduced in a time frame sufficient to create a dynamic underbalance condition to facilitate a surge flow of fluid from a reservoir into a wellbore. The pressure reduction mechanism may include singularly or in combination a heat sink to reduce the temperature of the detonation gas, a reactant to recombine with the reactant gas and reduce the molar density of the detonation gas, and a physical compression mechanism to utilize the waste energy of the detonation gas to create work, simultaneously reducing the temperature of the gas and the molar density of the detonation gas.

Abstract: A perforating device having a longitudinal axis comprising: a loading tube having an explosive charge; a first layer slidable, non fixedly, and removeably disposed over the loading tube; and at least one outer layer in fixed engagement over the first layer and wherein the outer layer is a solid structure.

Abstract: A combination for performing a variety of functions includes (a) apparatus for moving a projectile or other mass along an arcuate path and moving the path substantially radially along a local radius of curvature and (b) a tool, vehicle or other article for receiving such projectile and being moved thereby.

Abstract: The present invention provides for a perforating gun having stackable sections that latch, enabling the gun string to carry both compressive and tensile loads. This allows for the downhole assembly of guns of any desired length, and for the entire gun string to be removed after firing.

Abstract: The invention relates to a method to use a perforating gun in oil and natural gas wells, comprising: a perforating gun with a loading tube and explosive charge; the gun comprises: a first layer disposed over the loading tube and at least one outer layer in engagement over the first layer; the outer layer is a solid structure with scallop openings disposed therein and the scallops are in the solid structure in a defined pattern; wherein the method comprises: suspending the gun with a loading tube and explosive charge in a well bore wherein the gun has a longitudinal axis parallel to the sides of the well bore; detonating the explosive charge in the gun; permitting a gas jet to pierce the first layer and outer layer of the gun perpendicular to the longitudinal axis of the gun, well casing and to enter and fracture the strata surrounding the well.

Abstract: The borehole of many wells, including oil and gas production wells, is frequently cased with a steel or similar metal casing. In order to extract oil or other material existing within the surrounding geologic formation, it is necessary to puncture the casing. Currently, this is accomplished with tubes (guns) containing explosive charges being lowered into the well bore and detonated, causing the tube and well casing to be punctured and the geologic formation shattered. The guns are made from high strength, thick-walled and machined metal. This invention discloses a multi-layered or composite tube that enhances the directional orientation of the explosive charges utilizing less costly and more easily fabricated material. The invention also discloses a gun having properties to allow the desired directionally oriented perforation by the explosive charge without being deformed and jammed within the well casing. Other advantageous are also disclosed.

Abstract: Methods for evaluating drill pattern parameters such as burden, spacing, borehole diameter, etc., at a blast site are disclosed. One method involves accumulating the burden contributed by successive layers of rock and matching the accumulated rock burden to a target value for a borehole having a length related to the average height of the layers. Another method relates to varying drill pattern parameters and characteristics to match blast design constraints, including the substitution of one explosive material for another by the proper balance of materials and/or output energies to the associated rock burden. Analysis of deviations from target rock burdens and corrective measures are disclosed, as well as cost optimization methods. The various methods can be practiced using an appropriately programmed general purpose computer.

Abstract: An apparatus and method is provided to reduce interference resulting from activation of explosive devices. To reduce interference, one or more shock impeding elements are placed proximal one or more explosives to impede propagation of shock caused by detonation of the explosives. The shock impeding elements include a porous material, such as a porous liquid or solid.

Abstract: A downhole tool hydraulic firing head includes an automatic drain that is opened when the piston is driven to fire. The automatic drain includes a vent opening from the bore and a sleeve disposed within the bore to move axially with the piston. The sleeve is moveable from a position covering the vent opening to a position clear of the vent opening. A locking collet is disposed between the sleeve and the housing, which locks the sleeve into the position, clear of the vent opening, when the sleeve is moved into that position. This locks the sleeve against returning to the position covering the vent opening when it is urged to move in that direction such as, for example, by venturi forces of the evacuating fluid or by pressure generated from the explosive charges. The firing head is useful to detonate downhole explosive charges, such as those in a perforating gun.

Abstract: A soil sampler liner with areas of reduced wall thickness is defined by a continuous wall that has a reduced area extending along at least a portion of the length of the liner. The liner is inserted into the inner bore of a sampler probe, and a soil sample is taken by vertically inserting the probe and liner into the ground. The wall of the liner has at least two distinct areas of varying thickness; a reduced wall area and wall areas adjacent to the reduced wall area. The walls are sufficiently strong to withstand the forces applied to the liner when taking relatively large-diameter soil samples. The thickness of the wall at the reduced wall area is less than the thickness of the wall at the adjacent areas to permit a user to easily and safely cut through the wall at the reduced wall area and remove a large-diameter soil sample from the liner. The liner is also radially compressible into a flattened shape for compact and economical packaging and shipment of liners in relatively large quantities.

Abstract: A tunnel blasting method is disclosed. The method including the step of drilling blast holes such as cut holes, cut spreader holes, floor holes and roof holes to predetermined depths and in a predetermined hole arrangement. The blast holes are loaded with one or more detonators and explosives, stemming the blast holes with stemming materials. The detonators are detonated using a triggering device. In the hole loading step, one or more air bladders are situated in each of the blast holes so that a front free surface or one or more small free surfaces are formed. As a result, a projective area toward a free surface is enlarged and a total blast pressure is increased to increase the fragmentation rate of a rock and reduce blast vibration.

Abstract: A shaped charge is provided which includes features enhancing its manufacturability. In a described embodiment, an oilwell perforator is provided which includes a case and a liner, at least one of which is a molding. The molding has a metal loaded polymer matrix.

Abstract: The objects of the invention are provided using a method for horizontal drilling in which a shoe having an elbow-shaped cavity therein is lowered to a selected point. An explosive charge is placed at the far end of the shoe adjacent to the well casing. Impact transferring means are positioned between the explosive charge and the vertical portion of the well above the shoe. An impact is struck on the surface of the transfer means to cause an impact-type detonator to discharge, causing the explosive charge to discharge. This perforates the casing of the well at the tip of the shoe. The shoe and the tubing above it are then cleared and a hydraulic drilling device is inserted into the shoe. The shoe guides the hydraulic drilling device into place and high pressure liquid is pumped through the hydraulic device which extends through the perforation in the well casing into the earth's strata.

Abstract: A portable system for drilling geophysical shot holes in mixed geologic conditions. The system includes a drill for creating a shot hole in unconsolidated soil and for maintaining gauge in mixed geologic conditions. An explosive projectile for contacting hard rock is directed by a shot barrel, and a compressed air device removes residue from the shot hole. A controller can selectively discharge explosive projectiles when the drill bit encounters hard rock, and can cease the discharge of explosive projectiles when the drill bit encounters unconsolidated soil below hard rock. The system is particularly useful in preparing a slender shot hole in remote conditions restricting the mobility of drilling equipment, and in mixed geologic conditions comprising unconsolidated soils and hard rock aggregates or base rock.

Abstract: The present invention is directed to a cartridge for use in fracturing materials, such as rock. The cartridge includes a base member, a body member, a propellant, and a device for sealing a surface of the cartridge to the surface of a hole in the material. Upon ignition of the propellant, gas pressure rapidly rises in the hole due to the sealing device. The gas pressure causes the material to form a penetrating cone fracture. Various cartridge configurations are presented depending upon the specific needs of each application.

Abstract: A perforating gun using an electrical safe arm device and a capacitor exploding foil initiator device. The capacitor exploding foil initiator device having a capacitor connected in parallel to a bleed resistor which are connected across an exploding foil initiator by an over-voltage gap switch. When a voltage of the capacitor reaches a breakdown voltage of the switch, the energy stored in the capacitor is discharged through the switch to the exploding foil initiator which initiates a detonator cord thereby detonating the shaped charges of the perforating gun.

Abstract: Prior to pumping completion brine fluid into a wellbore, an additive comprising two percent (2%) of a 0.25% solution of polyacrylamide is blended into the completion brine fluid thereby producing a treated brine fluid. This blending would be performed in tanks at the wellsite. The treated brine fluid is then pumed into the wellbore. In addition, or in the alternative, a new perforating gun stores the polyacrylamide additive composition. When the perforating gun detonates, the additive is disbursed into the completion brine fluid disposed in the annulus of the wellbore. For example, the new perforating gun may include a plurality of shaped charges coated with a lacquer of the polyacrylamide additive, or it may include one or more containers which contain the polyacrylamide additive. When the brine completion fluid is pumped into the wellbore annulus, a detonation wave conducts in a detonating cord of the perforating gun. The detonation wave passes through each of the containers.

Abstract: In accordance with illustrative embodiments of the present invention, a safety bypass switch for use with explosive well tools includes a hollow conductive body having a copper conductor rod extending axially therethrough, a spring-loaded contact element movable transversely in the body between a first position where a surface of the element engages the rod to provide a solid short between the rod and the body, and a second position where such surface is out of engagement with the rod, and a diaphragm or piston for operating the contact element in a manner such that a predetermined hydrostatic pressure in the well bore will shift the contact element to the second position. The springs which bias the element toward the first position are mounted internally and externally of the body. In another embodiment of the invention a manually operated grounding switch is used in combination with the hydrostatic pressure operated switch to provide redundant assurance against accidental firing.