Method and apparatus for perforating subsurface earth formations

摘要

Method and apparatus for completing sursurface 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 can be detached and removed from the borehole. Additional percussion firing assemblies can be lowered into engagement with and removed from the firing head assembly as desired. Further, an electrical firing assembly can be lowered through the tubing string into engagement with 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.