Methods and apparatus for measuring a length of cable suspending a well logging tool in a borehole

摘要: Methods and apparatus are disclosed for measuring a length of logging cable introduced into borehole, thereby the depth tool, or sonde, attached to lower end cable. The methods involve producing an electrical signal, which propagates along cable, detecting at mouth borehole time passage initial signal subsequent reflected returned upwardly from or, alternatively, arrival upper These times can be determined by means clocks switched on off signal. Knowing intervals velocity propagation signals in thus is measured. Various embodiments including detectors do not electrically contact sensing necessary sonde.