Abstract: A depth measuring system for a slickline utilized in a well bore operation where the slickline is in a non-slip relationship with the circumference of a calibrated measuring wheel and the revolutions of the wheel are utilized to provide a first length measurement. A load cell is provided to measure tension in the slickline so that length elongation of the slickline due to tension can be determined. A temperature differential determination is made so that corrections in length can be made for the temperature effects. The temperature differential can be temperature effects on the measuring wheel and/or temperature effects of the slickline in the well bore. The measuring wheel determination of length is algebraically summed with the tension elongation and changes due to temperature to provide a more accurate indication of the depth measurement in the well bore.

Abstract: A measuring device is used for measuring the length of cable between a surface winch and a well tool in a well bore. A tension device measures tension on the cable supporting the well tool. Constant parameters for the cable, temperatures and coefficients are input to a CPU summation means which also receives measured data inputs of length and tension and determine the net change of cable length. The net change of cable length is used to constantly correct the length measurements sent to a recorder so the log depth is corrected for change in cable length due to wheel measurements, tension and temperature.

Abstract: In a cable length measurement system, two tangential measuring wheels engage the outer surface or an armored electrical cable and a magnetic mark detector is used for detecting magnetic marks located at a predetermined spacing on the cable while a tension load cell is connected to a cable sheave to measure tension on the cable; the detector in a system which utilizes a "window" period or span which is operated each 98 to 102 feet from a previous magnetic mark to detect valid magnetic marks on the cable which allows detection of magnetic marks substantially independent of the degree of wheel wear, slippage and/or damage; also in the detector system, the constant parameters for the cable, temperatures and coefficients are input to a CPU summation means which also receives measured data inputs of length and tension and the net change of cable length is determined; the net change of cable length is used to constantly correct the cable length measurements sent to a recorder so the log depth is corrected for change

Abstract: The present invention comprehends a magnetic mark detector system in which the magnetic detector head is customized to the magnetic span of the North/South poles of a magnetic mark on a cable and is focused to concentrate the specific magnetic characteristics of flux of the magnetic mark to a detector and to exclude the effects of extraneous earth magnetic fields. The magnetic head structure includes spaced apart elongated head members constructed from magnetic material and disposed in an end to end relationship. The head members have an overall length functionally related to the magnetic span of a magnetic mark and focus magnetic flux. Between facing ends of the head members, in a centrally located gap, is a Hall field effect device which responds to magnetic flux and produces an electrical output signal.