PREVENITOR DE ERUPTIE

摘要

A down hole blow out preventer which can be installed at the lower end of a drill string (71) as close as possible to the drill bit (72) and which can isolate an unexpected producing zone in a bore hole (73) from the rest of the hole by closing off the annulus (74) between the drill string and the wall of the bore by means of an inflatable packer (54). The packer can be operated when a predetermined pressure difference exists between the annulus and the mud column inside the tool.