Method and apparatus for effecting perforation of a well casing with a casing gun while maintaining pressure in the well bore at a lower level than the pressure in the surrounding reservoir at the point of perforation. Before production tubing is run into the well, the casing gun is deposited in the bore below the desired production level. After the tubing is installed, borehole pressure is reduced to the desired level by swabbing the tubing and an automatic coupling and decoupling pickup tool is lowered on a wireline through the tubing and attached, mechanically and electrically, to the casing gun. The casing gun is then raised to the production level, as measured by locating the casing collars. Whe the gun is properly located, it is activated through an electrical cable carried along with the wireline. The casing gun perforates the well casing and surrounding formation, and is then decoupled from the wireline to be left in the well.
An improved apparatus for releasing a perforation gun from a tubing string in a well casing is disclosed. The explosion of a detonator that fires the perforation gun opens a previously sealed passageway through a wall of the apparatus of the invention. The passageway transmits bottom hole well pressure to a piston that actuates means for releasing the perforation gun. A secondary release sleeve is also provided to mechanically release the perforation gun when the piston fails to function properly. In an alternate embodiment of the apparatus of the invention, the perforation gun is released when the explosion of the detonator breaks a frangible rod that previously held one or more retaining balls within a recess in a wall of the perforation gun assembly.
A method and apparatus for releasing a subterranean well perforating gun from a tubular string after firing of the subterranean well perforating gun. The apparatus comprises two telescopically inter-related tubular assemblies which are interconnected for axial co-movement solely by a plurality of radially shiftable latching elements. Such latching elements are normally maintained in a locked position by an annular piston. One end of the annular piston is exposed to gas at surface ambient pressure and the other end is exposed to the gas pressure generated in the perforating gun by its discharge and subsequently to the well fluid pressures produced by flow of well fluids through the perforations. The movement of the annular piston under such fluid pressure forces permits the locking elements to be cammed radially inwardly and release the connection between the tubular tool string and the perforating gun without any action on the part of the operator.
Method and apparatus for perforating a well casing (14) with a large pressure differential toward the well casing (14) from the surrounding oil and gas-bearing strata using a casing gun attached on a wireline below the tubing is disclosed. A perforator (12) is attached to a casing gun adapter (10), the casing gun adapter (10) is releasably attached to production tubing (16) and inserted into the well casing (14). After the production tubing (16) is installed, a collar locator (26) and a firing mechanism (44) are run on a wireline and attached to the casing gun adapter (10). The casing gun adapter (10) and the perforator (12) are released from the tubing and lowered to a predetermined stratum using a collar locator where the perforator (12) is detonated. After detonation, the perforator (12) and casing gun adapter (10) are raised and secured in the production tubing (16). The collar locator (26) and the firing mechanism (44) are detached from the casing gun adapter (10). A hold-down means (510, 610 or 710) is attached to the perforator (12) or to the casing gun adapter (10). The hold-down means (510, 610 or 710) holds the perforator (12) in the well casing (14) during perforation and prevents movement of the perforator (12) after perforation. In an alternate embodiment, the hold-down (610) wedges the perforator (12) in the well casing during and after perforation.
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.
4648471 - Control system for borehole tools - Owned by Schlumberger Technology Corporation (Houston, TX) [*] Notice:The portion of the term of this patent subsequent to July 9, 2002 has been disclaimed.
A method and apparatus for controlling a borehole tool, which tool has been conveyed into the borehole on production tubing. Apparatus includes a downhole control module connected to the tool for actuating and/or monitoring various subassemblies and/or events within the borehole. A communications link between the control module and the surface of the borehole is achieved with a wireline which has been terminated in a manner permitting electrical connection between the wireline and the control module to be made and broken in the downhole environment. Invention therefore combines the mechanical advantages of the rigid tubing for conveying the tool with the communication advantages of the wireline.
