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A valve used in a drill stem test tool has a ball movable between an open position to allow flow through the drill string for testing and a closed position to block flow. Operating means move the ball between the open and closed positions in response to pressures in the well annulus. A nitrogen fill

A valve used in a drill stem test tool has a ball movable between an open position to allow flow through the drill string for testing and a closed position to block flow. Operating means move the ball between the open and closed positions in response to pressures in the well annulus. A nitrogen filled pressure chamber and pressure balancing piston compensate for variations in annular pressure as the tool is being lowered into position in the well. Actuating means including a weight operated sleeve are operated from the surface to overcome the compensating effect of the pressure balancing piston to allow the ball to be rotated to the open position. The ball is spring biased toward the closed position by a coil spring located inside the pressure chamber. Relieving pressure in the annulus causes the spring to close the ball.

대표청구항 ▼

In a well annulus operated valve for drill string test tools having a ball rotatable between an open position to allow flow through the drill string for testing and a closed position to block flow through the drill string during placement and retrieval operations, wherein the improvement comprises:

In a well annulus operated valve for drill string test tools having a ball rotatable between an open position to allow flow through the drill string for testing and a closed position to block flow through the drill string during placement and retrieval operations, wherein the improvement comprises: a pair of shifting linkages extending from opposite sides of said ball, said linkages being adapted to shift in opposite relative directions to open and close said ball; a pressure operated inner mandrel slidably engaging the first of said shifting linkages, said mandrel being movable between extended and retracted positions responsive to pressures in the well annulus, thereby shifting said first linkage to rotate said ball; pressure balancing means movable between an active position responsive to pressure in the well annulus to prevent movement of said inner mandrel and a static position to allow movement of said inner mandrel; and actuating means for moving said pressure balancing means between said active and static position.