초록 ▼

This invention relates particularly but not exclusively to the secondary means for closing a bypass valve. A bypass valve (102) is provided which comprises a body (4) having a bore extending therethrough; at least one aperture (32) adapted to allow fluid communication between the bore and a chamber

This invention relates particularly but not exclusively to the secondary means for closing a bypass valve. A bypass valve (102) is provided which comprises a body (4) having a bore extending therethrough; at least one aperture (32) adapted to allow fluid communication between the bore and a chamber defined in the body (4); and at least one aperture adapted to allow fluid communication between the chamber and the exterior of the bypass valve. Fluid communication between the chamber and the bypass valve exterior is permitted when a piston (78) located in the chamber is in a first position, but is not permitted when the piston (78) is in a second position. Mechanism for selectively exposing the piston (78) to a pressure differential which moves the piston (78) is provided. A bypass valve is hereby provided which is more reliable than conventional bypass valve equipment.

대표청구항 ▼

[ We claim:] [16.]16. A bypass valve for selectively isolating the interior of a downhole assembly from the exterior thereof, the bypass valve comprising: a body having a bore for allowing the passage of wellbore fluid therethrough; a chamber defined in the body: at least one internal aperture provi

[ We claim:] [16.]16. A bypass valve for selectively isolating the interior of a downhole assembly from the exterior thereof, the bypass valve comprising: a body having a bore for allowing the passage of wellbore fluid therethrough; a chamber defined in the body: at least one internal aperture provided in the body for allowing fluid communication between the bore and the chamber; at least one external aperture provided in the body for allowing fluid communication between the chamber and the exterior of the bypass valve; and a piston slidably mounted in the chamber and movable between a first position in which fluid communication between the bore and the exterior of the bypass valve by means of the apertures is permitted and a second position in which fluid communication between the bore and the exterior of the bypass valve by means of the apertures is prevented, the piston being movable from the first position to the second position in response to a predetermined fluid pressure differential, wherein the or each internal aperture is located at the axially opposite end of the position to the or each external aperture; the piston comprises a passage providing fluid communication between the internal and external apertures; and retaining means is provided for selectively retaining the piston in the first position.