DOWNHOLE TOOL

摘要

A downhole tool (1) for providing a thrust force to an elongate body (5) extending in a borehole formed in an earth formation is provided. The tool (1) comprises at least one rotable body (15) provided with a plurality of rollers (23), each roller being expandable against the borehole wall at a selected contact force between the roller and the borehole wall. The rollers (23) are oriented when expanded against the borehole wall so as to roll along a helical path on the borehole wall, and a motor (7) is provided to rotate each rotatable body (15). The tool further comprises measuring means (6) to measure the thrust force provided by the tool and a control system (37) to control the thrust force provided by the tool (1) by regulating the rotative torque of the rotatable body, in response to the measured thrust force.