Wells – With explosive or gas generating means in well
Reexamination Certificate
1998-07-06
2001-05-01
Bagnell, David (Department: 3672)
Wells
With explosive or gas generating means in well
C166S055000
Reexamination Certificate
active
06223818
ABSTRACT:
BACKGROUND
This invention relates to improvements in the design for downhole equipment used in the completion of petroleum wells. More particularly, it relates to an improved design for a device used to create perforations in the well casing through which oil and gas are extracted from a reservoir.
In most conventional oil and gas wells the well is completed by cementing a string of steel casing in the well across the production zone near the bottom of the hole. Once this casing is in place production of the oil or gas is permitted by perforating holes in the casing opposite the production zone using shaped explosive charges known as a perforating gun.
Perforating guns for this purpose are normally lowered down the hole inside the casing on a cable (with an electrical connection) until the explosive charges are opposite the production zone. The electrical wires are energized to ignite the charges which pierce holes in the casing (and any surrounding cement) into the rock formation and allow the flow of the oil or gas into the well. These techniques are old and well known in the industry.
However, a problem often arises that with the explosion of the perforating charges the gun and attached cables and wires are often explosively driven up the well casing where they become tangled and jammed in the casing bore so that they cannot be removed by merely hoisting the cable. This often requires an expensive and time-consuming “fishing” operation to release the entanglement and retrieve the debris.
SUMMARY
It is therefore the purpose of this invention to provide a mechanism which may be attached to and lowered with a perforating gun and will effectively prevent the upward recoil of the equipment and the above-mentioned problems associated therewith.
More specifically, it is the purpose of this invention to provide a tool which may be attached to a perforating gun and will serve to grip the inner walls of the casing with enough resistance to create a breaking effect and prevent the upward recoil of the equipment and suspending cables immediately after the firing of the perforating gun.
It is also the purpose of this invention to provide a simple and relatively inexpensive mechanism which will automatically activate when the gun is fired and released shortly thereafter without elaborate control mechanism and without creating further problems in the retrieval of this equipment from the hole after the perforating operation is completed.
These objects and other advantages are achieved by the present invention which provides a brake mechanism for use in association with a petroleum well perforating gun and comprises a body with an outer shell having openings therein, brake plugs mounted in said openings to engage the casing of said well, a piston movable within said body and having a tapered portion designed to engage said plugs and move said plugs in the radial direction, orifice means to communicate pressure from said perforating gun to said piston to activate said plugs when the perforating gun is fired. The invention also has spring bias means to disengage said piston from said brake plugs when explosive pressure is not applied. The brake plugs may be released from engagement by a retractive spring means.
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patent: 4971146 (1990-11-01), Terrell
patent: 5700968 (1997-12-01), Blimke
Bagnell David
Dougherty Jennifer
Zarley McKee Thomte Voorhees & Sease
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