Casing perforation method and apparatus

A hold-down attached to perforator means comprising:

• a mandrel with a plurality of fins;
• a plurality of dogs attached to said mandrel, one dog attached to each of said fins, said dogs moving from a retracted position to an extended position wherein said dogs wedge against the inside diameter of a well casing;
• a collar fitting about said mandrel;
• a piston attached to said collar and pushing said collar against said dogs, thereby pivoting said dogs from the retracted position to the extended position;
• an inner cage secured to said mandrel;
• an outer cage slidably attached to said inner cage and moving from a first position wherein said dogs freely pivot to a second position wherein said outer cage disengages and shields said dogs from the well casing;
• and
• a plurality of splines defined in said outer cage, said splines securing said outer cage to said inner cage when said outer cage is in the second position.

A method of perforating the casing of a well at a predetermined stratum with a perforator means, comprising the steps of:

• running tubing with the perforator means releasably attached thereto into the well, the perforting means including a perforator larger in diameter than the inner diameter of the tubing;
• running an electrical cable extending from the well head into the well within the tubing for attachment to the perforator means;
• releasing the perforator means from the tubing after attachment to the electrical cable;
• positioning the perforator means opposite the predetermined strata by means of said cable;
• detonating the perforator means by a source of electrical energy at the well head;
• and
• reattaching the perforator means to the tubing by means of said cable.

A method for perforating the casing of a well at a predetermined stratum with a perforator means, comprising the steps of:

• running production tubing with a casing gun adapter, perforator means, and hold-down means releasably attached thereto into the well;
• positioning the casing gun adapter, the perforator means, and the hold-down means opposite the strata by means of a wireline;
• detonating the perforator means;
• wedging the hold-down means in the casing of the well by detonation of the perforator means;
• releasing the hold-down means from the casing;
• lifting the casing gun adapter, the perforator means, and the hold-down means to the production tubing;
• and
• reattaching the casing gun adapter, perforator means and hold-down means to the production tubing.

A method for perforating the casing of a well at a predetermined stratum with a perforator means, comprising the steps of:

• running production tubing with a casing gun adapter, the perforator means, and hold-down means releasably attached thereto into the well;
• running an electrical cable into the well within the production tubing for attachment to the casing gun adapter;
• releasing the casing gun adapter, the perforator means, and the hold-down means from the production tubing;
• positioning the casing gun adapter, the perforator means and the hold-down means opposite the strata by means of the electrical cable;
• detonating the perforator means to perforate the casing of the well and wedge the hold-down means in the well casing;
• releasing the hold-down means from the casing of the well;
• and
• reattaching the casing gun adapter, perforator means, and hold-down means to the production tubing.

The method for perforating the casing of a well at a predetermined stratum with a perforator means, comprising the steps of:

• running production tubing with a casing gun adapter, the perforator means, and a hold-down means releasably attached thereto into the well;
• running an electrical cable with a firing mechanism attached thereto into the well within the production tubing for attachment to the casing gun adapter;
• releasing the casing gun adapter from the production tubing when attached to the firing mechanism;
• positioning the perforator means at the predetermined strata by means of the electrical cable;
• detonating the perforator means by the firing mechanism connected to the electrical cable;
• and
• reattaching the casing gun adapter to the production tubing by means of the electrical cable.

A method for perforating the casing of a well at a predetermined strata by means of a perforator means, comprising the steps of:

• running production tubing with a casing gun adapter, the perforator means, and a hold-down means releasably attached thereto into the well;
• running a firing mechanism into the well;
• releasably attaching the firing mechanism to the casing gun adapter;
• positioning the perforator means to the predetermined strata;
• detonating the perforator means;
• wedging the hold-down means in the casing of the well by detonation of the perforating means;
• disengaging the hold-down means from the casing of the well;
• and
• reattaching the casing gun adapter to the production tubing.

Apparatus for use with a cable for positioning a perforator means in a well casing comprising:

• a cylindrical turret with a flared end, the flared end suitable for attachment to the perforator means;
• elastic members axially disposed on said turret;
• locating means attached to the cable;
• and
• a plurality of axially disposed splines attached to said locating means for releasably attaching said locating means to said turret.

Apparatus for holding a perforator means in a well casing comprising:

• a mandrel with a plurality of axially disposed mandrel fins and a cylindrical section extending from the fins;
• a first plurality of dogs pivotally attached individually to one of the mandrel fins, said first plurality of dogs pivoting from a retracted position to an extended position wherein the dogs wedge against the inside wall of the well casing;
• a cage with a plurality of axially disposed cage fins, said cage slidably mounted on the cylindrical section of said mandrel;
• a second plurality of dogs pivotally attached individually to the cage fins;
• and
• means for interconnecting in a paired relationship the dogs of said first plurality to the dogs of said second plurality.

A method for securing a perforator means for perforating a well casing at a predetermined strata in a well, comprising the steps of:

• attaching a hold-down means having releasable well casing engaging means to the perforator means;
• running production tubing with the perforator means releasably attached thereto along with the hold-down means in the well to a position above the predetermined strata;
• running an electrical cable into the well for attachment to the perforator means;
• releasing the perforator means from the production tubing;
• lowering the perforator means opposite the strata by means of the electrical cable;
• and
• detonating the perforator means to perforate the well casing and actuate said hold-down means to be wedged in the well casing.

Apparatus for holding a perforator means in a well casing comprising:

• a tapered mandrel with a plurality of fins disposed thereon;
• a plurality of dogs pivotally attached individually to one of said fins, said dogs pivoting from a retracted position to an extended position to be wedged against the inside wall of the well casing;
• an inner cage attached to said mandrel;
• and
• a housing attaching to said mandrel by said inner cage and having a plurality of longitudinal splines engaging a groove in said inner cage, said housing moving from a first position wherein said dogs freely pivot to a second position secured by said splines wherein said housing shields the dogs from engaging the well casing.