US 4,491,185 A · Method and apparatus for perforating subsurface earth formations

Abstract

Method and apparatus for completing subsurface formations traversed by a borehole. A perforating gun and a firing head assembly are run into the borehole on the end of a tubing string. A percussion firing assembly subsequently is lowered through the tubing string and latches into the firing head assembly. To initiate the firing system an impact member is dropped through the tubing string. Should ignition fail to occur the percussion firing assembly and a portion of the firing head assembly can be detached and removed from the borehole. An electrical firing assembly can be lowered through the tubing string into engagement with the remaining portion of the firing head assembly and an electrical control signal used to detonate the perforating gun. Should ignition again fail the electrical firing assembly is removed leaving a perforating system having no primary explosives therein, which can be removed from the borehole by pulling the tubing string.

Claims20

Dependent claims

A method for perforating subsurface earth formations surrounding a borehole, comprising the steps of:

positioning on the end of a tubing string a perforating gun and a firing head assembly within a borehole,
said firing head assembly including first and second explosive detonator assemblies mechanically and explosively serially aligned, said first detonator assembly detachably mechanically coupled to said second detonator assembly;
subsequently lowering through said tubing string a percussion firing assembly into coupling relationship within said firing head assembly;
and
dropping an impact member through said tubing string, the collision of said impact member with said percussion firing assembly for detonating said percussion firing assembly to thereby detonate said firing head assembly and said perforating gun.

2 more elements

Apparatus for perforating subsurface earth formations surrounding a borehole, comprising:

an elongated perforating gun having a plurality of radially directed shaped charges mounted therein;
a first explosive detonator assembly mechanically coupled to said perforating gun;
a second explosive detonator assembly mechanically coupled to said first detonator assembly, said second explosive detonator assembly being selectively detachable from said first explosive detonator assembly and aligned for transferring a detonating wave from said second detonator assembly to said first detonator asssembly;
and
a percussion firing assembly adapted for latching engagement with said second detonator assembly.

2 more elements

Dependencies are inferred from the claim text.

Method and apparatus for perforating subsurface earth formations

Life of this patent

Method and apparatus for perforating subsurface earth formations

Life of this patent

Abstract

Claims20