Self adjusting liquid spring operating apparatus and method for use in an oil well valve

An oil well valve operating apparatus containing a volume of compressible liquid responsive to changes in pressure in the annulus of the oil well comprising:

• a tubular housing having a power port through the walls thereof;
• a tubular power mandrel axially aligned with and slidably located in said housing and having an annular chamber between said power mandrel and said tubular housing for containing said volume of compressible liquid, said power mandrel being operatively connected to said oil well valve for moving said valve from a first position to a second position;
• a floating piston in said annular chamber exposed on one side to well annulus pressure communicated to said one side by said power port, and exposed on a second side to the pressure of compressible liquid in said annular chamber;
• positioning means between said power mandrel and said tubular housing for preventing said power mandrel from moving past a predetermined position in relation to said tubular housing when said power mandrel is moving in a first given direction with respect to said tubular housing;
• power piston means on said power mandrel dividing said annular chamber and separated from said power port by said floating piston;
• spring means between a portion of said tubular housing and a portion of said power mandrel to return said power mandrel to said predetermined position after said power mandrel has moved in a direction opposite from said first direction due to changes in the pressure in said well annulus, said pressure changes being transmitted to said power piston through said power port, said floating piston and a portion of the compressible liquid between said floating piston and said power piston;
• and
• liquid metering means for passing the compressible liquid from one side of said power piston to the other side of said power piston for balancing in a predetermined relatively slow manner any pressure imbalance between portions of said divided annular chamber.

A method of operating a valve in an oil well comprising:

• providing a volume of compressible liquid in a chamber in an oil well apparatus;
• dividing the compressible oil chamber with a piston having a metering means therethrough;
• urging the piston in a first longitudinal direction to an initial position with a spring means;
• transmitting pressure exterior of the apparatus to one side of the piston;
• lowering the apparatus into the oil well to a predetermined depth;
• metering changes in pressure and volume of the compressible oil through said metering means from one side of the piston to the other side;
• changing the pressure in the well bore exterior of the apparatus at a rate faster than relievable by said metering means;
• moving the piston in a second longitudinal direction against said spring means responsive to the pressure differential across said piston;
• metering compressible oil through said metering means and moving said piston by said spring means in the first longitudinal direction back to its initial position;
• and
• responsive to said motions of said piston, activating a valve in said oil well.