Patent ID: 8973663
Filing Date: 2015-03-10
Classification: E21B

Abstract:
1. A well tool for use in a tubing string extending to a subterranean location in a hydrocarbon well, comprising: an elongated, tubular-shaped body for assembly in the tubing string, the tubular body isolating the exterior from the interior of the body; at least one valve on the body having a valve element movable between an open and a closed position to permit and prevent flow through the valve; a tubular piston mounted on the body for longitudinal movement with respect to the body, the piston operably associated with the valve element to move the valve element; a variable volume chamber in an annular space between the body and the piston, a passageway in the body providing fluid communication between the chamber and the exterior of the body; seals between the body and piston sealing pressure within the chamber during longitudinal movement of the piston, and wherein at least one of said seals is a unidirectional seal, preventing flow of the fluids out of the chamber and permitting flow into the chamber; and wherein the unidirectional seal comprises an annular seal mounted in a groove surrounding the piston, and wherein at least one circumferentially discontinuous recess is formed in the groove.