| 摘要 |
A pressure differential drilling tool is described for reducing pressure in the annulus between a drill string and a wellbore in a drilling zone. The pressure differential drilling tool includes (a) a jet pump including a power nozzle having a nozzle inlet, a pump inlet, a pump outlet and a drilling fluid conduit extending between the pump inlet and the pump outlet and in communication with the power nozzle, the jet pump being connectable into the drill string such that the nozzle inlet is accessible from the drill string inner bore and the pump inlet and the pump outlet open into the annulus (b) a bypass port for fluid through the drill string inner bore and bypass around the jet pump and (c) the wellbore pack off seal positioned about the jet pump between the pump inlet and the pump outlet and operable to create a seal preventing fluid communication between the pump inlet and the pump outlet except through the fluid conduit and being moveable with the jet pump, while in operation, through the wellbore. |
