Packer annulus differential pressure valve

Abstract

The invention is a well fluid production valve that is positioned downhole in a closed condition below an upper formation packer. The valve comprises a cylindrical mandrel having central bore flow connection with the upper bore of well fluid production tubing and coaxially aligned within the lower bore of the production tubing string. Flow port apertures through the mandrel wall provide well fluid flow paths between the mandrel O.D. and the bore I.D. of the lower production tubing. These flow ports are covered to close the valve by a sliding sleeve around the mandrel O.D. The sliding sleeve is spring biased to the open position but also secured at the closed valve position by an annular piston actuated sear mechanism. Actuation pressure for opening the valve to admit a flow of well fluids from the production zone is a predetermined differential between the well pressure above the packer, usually a function of the well depth, and the operator controlled pressure within attached production tubing. The formation pressure, which may be more or less than the corresponding head pressure, is isolated from the valve actuator and therefore does not contribute to the valve actuating pressure. A fluid pressure conduit is provided that transmits fluid pressure from a well annulus zone above the upper formation packer down past the packer to the upper face of the annular piston within an annular valve actuation cylinder. Production tubing bore pressure is routed to bear upon the lower face of the annular piston. Sufficient pressure differential on the annular piston displaces the sear piston from the sleeve holding position with the sear piston removed. The standing spring bias on the sleeve slides it along the mandrel O.D. to open the flow ports.