SELF ADJUSTING LIQUID SPRING OPERATING APPARATUS AND METHOD FOR USE IN AN OIL WELL VALVE

摘要

Disclosed is an apparatus and its method of operation for an oil well valve having a self adjusting liquid spring responsive to changes in pressure in the well annulus. The valve has a liquid spring contained in a spring chamber divided by a piston means which moves responsive to annulus pressure changes to operate the valve. The piston means includes a metering means to meter liquid from one side of the piston to the other as the volume of the liquid changes due to pressure and temperature changes. The piston means moves responsive to pressure changes in the well annulus which pressure changes are applied to the well annulus at a rate faster than the metering means may relieve the changes. A mechanical spring means in conjunction with the metering means returns the piston means to its original position after a predetermined time. Bypass means is additionally disclosed which bypasses the metering means and may be arranged such that piston means movement occurs on either pressure increases or pressure decreases in the well annulus.