Annulus cementing tool for well abandonment

摘要

A method for abandonment of a subsea well includes fastening a pressure control assembly (PCA) 20, (fig 2A) to a subsea wellhead 10 and deploying a tool string into the PCA. The tool string includes a packer 215 and an upper perforator 209 located above the packer 215. The method further includes closing a bore of the PCA above the tool string with a solid barrier (115v fig 4A); and setting the packer against an inner casing hung from the subsea wellhead. While the PCA bore is closed, a wall of the inner casing is perforated by operating the upper perforator 209. Cement slurry is injected into an inner annulus formed between the inner casing and an outer casing hung from the subsea wellhead - see figs 3A-3H. A perforating gun is also claimed and includes a blasting cap 231 and shaped charges 226 disposed in a chamber 242 which is isolated from a bore 223b formed through the exterior of the gun. A firing mechanism operating in response to a piston 238 strikes the blasting cap 231 and the chamber 242 remains isolated from the bore 223b after firing of the charges see figs 5D-5F.