Abstract: An apparatus and method for controlling the pressure at which a fluid is introduced into a well penetrating a subterranean formation. The apparatus comprises a blow out sub having a sealed chamber between two plugs. The chamber is filled with a fluid at a known pressure. Thus, the pressure required to release the first plug is independent of the pressure in the well below the sub. The sub is attached to a tubular and positioned within the well. The first plug is then released upon application of a predetermined pressure fluid pressure, and the second plug is released upon application of a lesser pressure. The blow out sub may additionally comprise a tube forming a channel through the first plug, the chamber, and the second plug, with a means for controlling fluid flow through the channel. A first fluid may be introduced into the well via the channel prior to releasing the first plug.

Abstract: A downhole tool apparatus for use in a well includes a housing having a cylindrical chamber defined therein. A power piston is slidably disposed in the cylindrical chamber and divides the cylindrical chamber into first and second chamber portions on opposite sides of the power piston. First and second explosive charges are contained within the housing and communicated with the first and second chamber portions on opposite sides of the power piston. Firing of the first explosive charge moves the power piston in a first direction. Firing of the second explosive charge moves the power piston back in a second direction opposite the first direction. Thus, the operating power for a downhole tool is provided by selective firing of explosive charges which provide the operating pressure to move the power piston of the tool.

Abstract: The device of the present invention comprises first means for initiating a first combustive reaction which is actuated in response to a first pressure condition in at least a portion of the well bore, means to initiate any desired number of additional combustive reactions, and means for actuation an explosive charge to actuate perforating guns, or the like, in the well bore.

Abstract: A hydraulically actuated firing head for a tubing conveyed well perforating system includes an actuating piston responsive to a differential between tubing pressure and a sealed low pressure zone contained within the firing head. The actuating piston releases a firing piston which initiates a firing sequence.

Abstract: A method and apparatus for perforating a subsurface formation in a pumped well. An assembly is provided which facilitates both the support of a pump in a tool string and the convection of fluid, and pressures, around the pump in the tool string. A firing head associated with the perforating gun is actuated by a pressure of differential between the tubing string bore and the wellbore annulus. This pressure differential is achieved by a downhole pump which pumps fluid out of the wellbore into the tubing string bore.

Abstract: The described invention includes an apparatus for perforating a well through use of one or more perforating guns in a collapsible perforating assembly. The collapsible perforating assembly includes a collapsible spacer mandrel which may be placed between two or more perforating guns. The spacer mandrel will be adapted to keep the guns in a desired spaced relationship prior to actuation of the guns. After actuation, the gun spacer assembly will be allowed to telescopically collapse in length. When the perforating assembly is then released from the tubing string and dropped to the bottom of the well, the assembly will collapse, decreasing the amount of rat hold necessary to accommodate the perforating assembly.

Abstract: The invention provides a perforating assembly and a method and apparatus for retaining shaped charges in a charge carrier. A shaped charge body has two clips associated with it: a band clip having a plurality of radially extending tabs oppositely oriented for mounting the shaped charge body in the charge carrier, and for securing the shaped charge body in place; and a wire clip mounted on the shaped charge body and adapted to hold a detonating cord in contact with the shaped charge.

Abstract: A firing head assembly for a well bore perforating gun in which alternative firing paths are provided. A first detonation cord passes longitudinally through a generally cylindrical housing, providing a firing path from a firing head above the housing to a perforating gun below the housing. A firing pin and second detonation cord are located in the housing and are positioned radially offset from the longitudinal axis of the housing. Boosters on the first and second detonation cords are positioned adjacent one another and opposite a third booster. Either or both of the first and second boosters may be used to fire the third booster. No splicing of detonation cords is required and the detonation cords are completely contained within a protective housing. The firing pin may be actuated by pressure or mechanical means.

Abstract: The present invention includes devices for absorbing shock in a tool string within a borehole. These components may serve together in a variety of configurations to form a shock absorbing system. A longitudinal shock absorber is connected in the tool string. The longitudinal shock absorber includes compressible members utilized to damp longitudinal movement. A radial shock absorber is connected in the tool string. The radial shock absorber includes resiliently mounted contact pads for contacting the sides of the borehole to damp radial movement. A carrier assembly is utilized to provide a shock absorbing mounting for particularly delicate components such as gauges, and to damp any shock which might be transmitted thereto from either a radial or longitudinal direction.

Abstract: A tool for activating the firing head of a perforating gun located below a packer by applying pressure to the upper well annulus while maintaining an unimpeded bore between the perforating gun and the pipe string. The tool is provided with a flow valve to prevent flow through the flow bore when closed, and a circulation valve which permits fluid flow from the upper annulus into the flow bore when open and a means of switching the valves so that when one is open the other is closed. A method of using the tool to complete a well is also disclosed.

Abstract: A vent subassembly includes a vent body having an opening which is covered or uncovered dependent upon the location of a vent sleeve relative to the vent body. The vent subassembly can be connected below a packer, and the vent sleeve can be connected to a perforator so that movement of the vent sleeve is concurrently communicated to the perforator, such as for initiating the firing of the perforator. The vent sleeve is moved by an actuator subassembly, which is to be connected above the packer if the vent and actuator subassemblies are used with a packer. The actuator subassembly has a piston housing, a piston slidably disposed in the piston housing, and a connector string extending from the piston to the vent sleeve. The piston is responsive to a differential pressure existing between the annulus outside the actuator subassembly and an interior pressure within the actuator subassembly.

Abstract: A detonator bar has an outer housing, an inner housing connected to the outer housing by at least one first frangible member, an explosive charge disposed in the inner housing, and a firing piston with firing pin held in the inner housing by at least one retaining dog and at least one second frangible member. Operation occurs in response to a relatively small impact force between the detonator bar and a perforator or other explosive object located in a subterranean well. This relatively small impact breaks the at least one first frangible member.

Abstract: A vent subassembly includes a vent body having an opening which is covered or uncovered dependent upon the location of a vent sleeve relative to the vent body. The vent subassembly can be connected below a packer, and the vent sleeve can be connected to a perforator so that movement of the vent sleeve is concurrently communicated to the perforator, such as for initiating the firing of the perforator. The vent sleeve is moved by an actuator subassembly, which is to be connected above the packer if the vent and actuator subassemblies are used with a packer. The actuator subassembly has a piston housing, a piston slidably disposed in the piston housing, and a connector string extending from the piston to the vent sleeve. The piston is responsive to a differential pressure existing between the annulus outside the actuator subassembly and an interior pressure within the actuator subassembly.

Abstract: A low actuation pressure bar vent for use in a tool string having low pressure therein. The vent includes a body portion and a piston slidingly disposed in the body. The piston and body define a first cavity therebetween and a second cavity therebetween, spaced from the first cavity. The body further defines a plurality of transverse ports therethrough providing communication between a body central opening and a well annulus. When in a closed position, the piston sealingly closes the ports. In a first embodiment, the first cavity has a spring disposed therein. The body also defines a second plurality of ports therein providing fluid communication between the first cavity and the well annulus. Pressure in the well annulus and the spring bias the piston toward an open position uncovering the ports. In an alternate embodiment, a pressurized gas biases the piston. The second cavity is filled with a fluid such that movement of the piston is prevented.

Abstract: The present invention includes devices for absorbing shock in a tool string within a borehole. These components may serve together in a variety of configurations to form a shock absorbing system. A longitudinal shock absorber is connected in the tool string. The longitudinal shock absorber includes compressible members utilized to damp longitudinal movement. A radial shock absorber is connected in the tool string. The radial shock absorber includes resiliently mounted contact pads for contacting the sides of the borehole to damp radial movement. A carrier assembly is utilized to provide a shock absorbing mounting for particularly delicate components such as gauges, and to damp any shock which might be transmitted thereto from either a radial or longitudinal direction.

Abstract: Systems and methods for surging fluid downhole in an earth borehole, as well as tools especially adapted for use in such systems and methods, are disclosed. In a system for surging fluids, upper and lower valves both operated through the use of annulus pressure define the upper and lower extremities of a surge chamber. In a multiple surge system, first and second surge chambers are provided and a further valve is operative to surge fluids from the first surge chamber into the second surge chamber. A valve is disclosed having a longitudinal passageway initially closed by a breakable closure member. The valve is opened by breaking the closure member, and removing the broken closure member from the longitudinal passageway. The valve is operated by pressure differential between annulus pressure and atmospheric pressure which serves to accelerate a massive cutter member into the closure member for opening it. Also, a fluid pressure actuated apparatus especially useful in operating the upper valve is disclosed.

Abstract: A downhole tool includes a pipe string portion which is disposed in a pipe string of a well and a probe portion which can be lowered by wireline or other suitable means into the well for engagement with the pipe string portion. The pipe string portion includes a sliding sleeve valve which is biased in a closed, or unactuated position, by a spring contained within the pipe string portion. The probe portion includes a connector mechanism which engages lugs of the pipe string portion for imparting an opposing force to the sliding sleeve valve which overcomes the biasing force of the spring so that the valve can be opened to permit reservoir pressure to enter a cavity of the probe portion containing a sensor mechanism. The coupling and decoupling of the connector mechanism with the lugs is effected through two downward and two upward movements of the probe portion.