Patent ID: 8701778
Filing Date: 2014-04-22
Classification: E21B

Abstract:
1. A downhole tester valve comprising: a housing assembly; a mandrel assembly disposed within the housing assembly defining therebetween an operating fluid chamber, a biasing fluid chamber and a power fluid chamber; a valve assembly disposed within the housing assembly operable between open and closed positions; and a piston assembly operably associated with the valve assembly, the piston assembly having first and second sides, the piston assembly including a collet assembly and a snap sleeve having first and second positions relative to the collet assembly; wherein, an increase in annulus pressure entering the power fluid chamber pressurizes operating fluid in the operating fluid chamber which acts on the first side of the piston assembly to shift the valve assembly from the closed position to the open position; wherein, predetermined travel of the piston assembly opens a bypass passageway for the pressurized operating fluid to charge biasing fluid in the biasing fluid chamber; and wherein, a reduction in annulus pressure reduces the operating fluid pressure acting on the first side of the piston assembly such that the charged biasing fluid acting on the second side of the piston assembly shifts the valve assembly from the open position to the closed position; and wherein a first portion of the piston assembly is shiftable relative to a second portion of the piston assembly such that the collet assembly releases the snap sleeve prior to the piston assembly shifting the valve assembly from the closed position to the open position.