Patent ID: 7295926

Claim:
A method of correcting depth of logging data measured by a logging system mounted on an elongate member extending through a wellbore to the surface comprising the steps of: (a) receiving sets of logging data for two or more spatially overlapping logs generated by the logging system, each set comprising measures of a characteristic associated with the wellbore at longitudinally spaced positions along the wellbore; (b) receiving measurement data for the period or periods of log generation, the measurement data comprising measurements of the load on the elongate member and measurements of the surface position of the elongate member; (c) determining a compliance parameter representing the compliance of the elongate member by comparing at least two of the sets of logging data depth corrected using a plurality of values for the compliance parameter, and selecting a value for the compliance parameter that yields a high degree of consistency between the at least two sets of logging data; (d) correcting the depth of at least one set of logging data measured using the logging system, using a correction function which relates the position of the logging system to at least (i) the measured load on the elongate member, (ii) the measured surface position of the elongate member, and (iii) the selected compliance parameter of the elongate member; and (e) outputting the corrected logging data to provide for corrective action based on the corrected logging data.