A METHOD OF PROVIDING IMPEDANCE VALUES FOR USE IN A METHOD OF SYNTHESIZING THE RESPONSE CHARACTERISTICS OF BOREHOLE LOGGING TOOLS

摘要

The response characteristics of a combination of hole-centered electric logging tools in a variety of borehole conditions can be obtained by means of impedance values as entries of a matrix resulting from measurements over a series of depth increments, utilizing an array of M electrode assemblies of equal incremental spacing positioned on a rigid mandrel. While the array moves continuously along the borehole, currents are emitted independently and sequentially from first one and then the other of current electrodes located at the shallow and deep ends of the array, allowing the impedance matrix to be formed by the principle of linear superposition in terms of voltage and voltage difference measurements between adjacent electrodes. The impedance matrix is inverted and used to generate a set of tool responses, which when properly compared to a set of tool responses previously generated by computer simulation and addressable by sets of borehole parameters and calibration factors, allows the corresponding borehole conditions to be deduced from the measured data.