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.

Abstract: A single ram unidirectional wireline BOP system is provided having both mechanical and hydraulic sealing capability. A BOP body having a vertical flow passage and intersecting horizontal ram passages includes a single pair of opposed rams and appropriate actuators for moving the rams into sealing engagement with a wireline extending through the vertical flow passages. Each of the rams incorporates an elastomeric peripheral seal extending about a major portion of the periphery thereof and disposed for sealing engagement with internal wall surfaces of the body. The sealing system of the rams also incorporates a pair of vertically spaced inner elastomeric seals disposed for sealing engagement with one another and with the wireline. Between the upper and lower inner seals in the closed positions of the rams, is defined a small, centralized grease chamber through which the wireline extends.