Pull-down method and equipment for installing well casing

摘要

A drilling rig having a top drive has a pipe gripper with a mandrel having an upper end for connection to and rotation with a drive string extending downward from the top drive. The pipe gripper has gripping elements that move radially into engagement with a string of pipe. A pull-down mechanism is mounted to the rig and secured to a non-rotating portion of the pipe gripper for exerting a downward force on the mandrel. A sensor is operatively coupled to the top drive to sense weight being supported by the top drive. A controller is linked to the sensor and the pull-down mechanism for controlling the downward force exerted on the mandrel by the pull-down mechanism in response to the weight sensed by the sensor.

主权项

1. An apparatus for performing well construction operations with a drilling rig having a top drive, comprising:
a pipe gripper having a mandrel with an upper end for connection to and rotation with a drive string extending downward from the top drive, the pipe gripper having gripping elements that move radially into engagement with a string of pipe; a pull-down mechanism adapted to be mounted to the rig and secured to a non-rotating portion of the pipe gripper for selectively exerting a downward force on the mandrel, wherein the pull-down mechanism comprises a pair of winches, each adapted to be mounted to the rig below a rig floor; and a cable wrapped around each of the winches, each of the cables adapted to pass through a hole or respective holes in the rig floor into operative engagement with opposite sides of the non-rotating portion of the pipe gripper.