Normally closed retainer valve with fail-safe pump through capability

摘要

A retainer valve provides increased safety in wellsite operations. In a preferred embodiment, operation of the retainer valve may be responsive to control line pressure or to tubing pressure. The retainer valve response is controlled by several factors, among which are relative tubing and balance line pressures, and axial positions of a number of pistons relative to a tubular J-slot member. If the control and balance lines are disconnected, or otherwise unavailable for operation of the valve, it may still be operated by manipulation of the tubing pressure at the earth's surface. Thus, the valve may be opened in emergency situations in which the control and balance lines are unavailable, but operation of the valve is still needed in order to safely relieve trapped pressure in the tubing string and/or to kill the well, unlatch a subsea test tree, etc. The retainer valve is also useful as a lubricator valve.