Patent ID: 8757267

Claim:
A system for enhancing gas recovery from a wellbore extending to a reservoir having diminished pressure, the wellbore having a tubing string therein, a packer and compressed gas for pressurizing a wellbore annulus, the packer being set, above perforations, between a casing string and the tubing string for forming the wellbore annulus thereabove, liquids accumulating in a bore of the tubing string as wellbore gas is produced therethrough to surface, the system comprising: a one-way valve at a bottom of the tubing string for one-way fluid communication from the reservoir to the tubing string; and a pressure-actuated valve, housed in the bore of the tubing string uphole from the one-way valve and forming a production annulus therebetween in fluid communication with the tubing annulus, the pressure-actuated valve comprising: a valve body having a valve bore; inlet ports for fluid communication between the wellbore annulus and the valve bore; outlet ports in the valve body, spaced downhole from the inlet ports, for fluid communication between the valve bore and the production annulus; a plunger axially moveable in the valve bore, uphole from the inlet ports, for alternately blocking the inlet ports for preventing gas accumulating in the wellbore annulus from entering the valve body in a closed, production position; and unblocking the inlet ports for admitting gas from the wellbore annulus to the valve bore and flowing through the outlet ports to the production annulus for lifting accumulated fluids therein to surface in an open, lift position; a main spring operatively connected to the plunger for normally biasing the plunger downhole to the production position; and a pressure-actuated pilot valve system positioned in the valve bore and in continuous pressure communication with the wellbore annulus, wherein when the pressure in the wellbore annulus exceeds a preset high pressure, the pilot valve opens to communicate the high pressure to the plunger for overcoming the biasing and moving the plunger from the production position to the open, lift position; and when the pressure in the wellbore annulus is below a preset low pressure, the pilot valve releases the pressure acting at the plunger, allowing the plunger to be biased from the lift position to the closed, production position.