Abstract: A differential pressure valve has a valve body containing a main piston axially moveable therein to open a fluid inlet to a fluid outlet at preset high pressure and to close at a preset lower pressure. A high pressure trigger piston and a low pressure trigger piston are operable in the main piston to alternately engage and lock the main piston to the valve body in one of the closed and open positions. A ball shifts in a port in the main piston to alternately straddle between at least one annular locking groove in the valve body and a release recess in a respective trigger piston. The ball can shift to alternately reside to straddle the valve body and main piston in the locked position or to straddle the main piston and trigger piston in the unlocked position. The trigger pistons and main pistons are mechanically biased to urge the pistons against the fluid pressure at the inlet.

Abstract: A system is provided for unloading accumulated liquids and enhancing the recovery of gas from a reservoir having diminished pressure. An annulus between a tubing string and casing is isolated by a packer and continually pressurized with a slipstream of compressed gas while the well continues to produce. A unique valve positioned in the tubing string is shuttled between a production position in which production fluids are permitted to bypass the valve to the surface and a lift position in which the bypass is blocked and an unloading port is opened to vent high pressure annulus gas to the tubing string above the valve, lifting accumulated liquids with it. Preferably, the valve is actuated to the lift position by the impact of a plunger dropped from a lubricator at the wellhead, when the pressure in the annulus has reached a predetermined threshold.

Abstract: A system is provided for unloading accumulated liquids and enhancing the recovery of gas from a reservoir having diminished pressure. An annulus between a tubing string and casing is isolated by a packer and continually pressurized with a slipstream of compressed gas while the well continues to produce. A unique valve positioned in the tubing string is shuttled between a production position in which production fluids are permitted to bypass the valve to the surface and a lift position in which the bypass is blocked and an unloading port is opened to vent high pressure annulus gas to the tubing string above the valve, lifting accumulated liquids with it. Preferably, the valve is actuated to the lift position by the impact of a plunger dropped from a lubricator at the wellhead, when the pressure in the annulus has reached a predetermined threshold.

Abstract: A system is provided for unloading accumulated liquids and enhancing the recovery of gas from a reservoir having diminished pressure. An annulus between a tubing string and casing is isolated by a packer and continually pressurized with a slipstream of compressed gas while the well continues to produce. A unique valve positioned in the tubing string is shuttled between a production position in which production fluids are permitted to bypass the valve to the surface and a lift position in which the bypass is blocked and an unloading port is opened to vent high pressure annulus gas to the tubing string above the valve, lifting accumulated liquids with it. Preferably, the valve is actuated to the lift position by the impact of a plunger dropped from a lubricator at the wellhead, when the pressure in the annulus has reached a predetermined threshold.

Abstract: A system is provided for unloading accumulated liquids and enhancing the recovery of gas from a reservoir having diminished pressure. An annulus between a tubing string and casing is isolated by a packer and continually pressurized with a slipstream of compressed gas while the well continues to produce. A unique valve positioned in the tubing string is shuttled between a production position in which production fluids are permitted to bypass the valve to the surface and a lift position in which the bypass is blocked and an unloading port is opened to vent high pressure annulus gas to the tubing string above the valve, lifting accumulated liquids with it. Preferably, the valve is actuated to the lift position by the impact of a plunger dropped from a lubricator at the wellhead, when the pressure in the annulus has reached a predetermined threshold.