Apparatus for measuring the relative position of a downhole tool in a bore hole

摘要

An apparatus for accurately determining the relative positioning of a well logging sonde or downhole tool in a bore hole is disclosed. The apparatus comprises an anchor for engaging the wall of the bore hole in fixed position and adapted to be carried into the bore hole on the downhole tool suspended on a logging wireline to a selected level, and a release mechanism controllable from the surface for releasing the anchor from the tool so that the tool can move independently of the anchor element. A sensing cable interconnects the anchor and the tool and is payed out from a reel carried by the tool as the tool separates from the anchor. Means actuated by the sensing cable are provided for transmitting electrical pulses up the wireline to the surface to indicate the relative distance between the anchor and tool.