Downhole tool for use in a drill string

摘要

A downhole tool in a drill string for mitigating hazards of a blockage in an annulus of the drill string. The downhole tool can sense blockages and selectively recirculate flow from within the annulus back to surface. Further, the downhole tool is made up of segments that are selectively detachable from one another, so that the segments above the point of detachment are removable from a wellbore. The bypass assembly includes a sleeve in the downhole tool with openings in its side; when the annulus reaches a set pressure, the sleeve slides to a position so the openings register with ports formed through a side of the tool to allow bypass flow. A processor in the downhole tool senses movement of the string, and when the string is axially stationary more than a designated period of time, the processor emits signals to detach the segments.

主权项

1. A downhole sub that is selectively coupled in series with a drill string comprising:
a bypass sub having a housing with an outer surface; a bore axially disposed in the housing; a relief valve assembly in a side wall of the housing that is selectively moveable from a closed position with the outer surface isolated from the bore to an open position with the fluid communication between the bore and outer surface; and a passage in the side wall of the housing having an end in communication with the bore and a distal end in communication with the relief valve assembly that terminates within the housing and that is isolated from the outer surface of the housing, the passage selectively routing fluid from the bore to the relief valve assembly, so that when the fluid in the bore is at a designated pressure, the fluid in communication with the relief valve assembly exerts a force onto the relief valve assembly to move the relief valve assembly into the open position.