Patent ID: 6173795
Filing Date: 2001-01-16
Classification: E21B

Abstract:
A multi-cycle circulating sub for selectively providing fluid communication between the interior of a downhole assembly and the exterior thereof, the multi-cycle circulating sub comprising:a body incorporating a wall provided with at least one aperture extending therethrough;a sleeve having a longitudinal bore extending therethrough and being slidably mounted in the body so as to be moveable between a first position relative to the body preventing fluid communication between the bore of the sleeve and the exterior of the body via the or each aperture and a second position relative to the body permitting fluid communication between the bore of the sleeve and the exterior of the body via the or each aperture; andcontrolling means for controlling the movement of the sleeve between the first and second positions;the controlling means comprising:a control member slidable in the body and moveable by fluid pressure in the body in a first axial direction relative to the body;a spring biasing the control member in an opposite axial direction of the body; a pin secured to one of the body and the control member; anda control groove formed in the other of the body and the control member, the control groove receiving a portion of the pin and being shaped to limit axial displacement of the control member in response to pressure variations in the body such that only after a predetermined number of movements of the control member to a first limit position is the control member able to move to a second limit position to displace the sleeve into the second position of the sleeve;wherein the control member is moveable in the body independently of the sleeve.