Hydraulically energized wireline blowout preventer

Abstract

A single ram wireline BOP mechanism is disclosed which incorporates opposed rams having elastomeric packing capsules and outer elastomeric seals for accomplishing sealing about a wireline extending through the BOP body. The packing capsules cooperate to define a centrally oriented grease chamber into which is injected grease from an externally accessible grease fitting so as to establish grease sealing about the wireline. Grease pressure from the grease chamber is ducted through the BOP rams and into inner cylinders where it acts upon the pressure responsive area of a free piston contained therein. The grease pressure develops a force on the free piston which acts against the ram to enhance the closing force of the ram. The free piston has a pressure responsive area significantly greater than the pressure responsive area of the packing capsule portion of the ram so that grease pressure acting upon both of these components develops a significant resultant force that enhances the closing force and thus sealing capability of the rams. The rams are also operated in the closing and opening directions by hydraulic fluid which is introduced through fittings into an outer hydraulic cylinder. The BOP mechanism is also provided with a non-rising stem type lock out device which drives a lock nut for securing the ram energizing piston in its closed position when desired. The apparatus also incorporates a position indicator stem which is coupled with the ram energizing piston so that the position of the piston and rams may be visually inspected.