METHOD OF BOREHOLE COMPENSATION OF EARTH FORMATION CHARACTERISTIC MEASUREMENTS USING DEPTH MEASUREMENTS

摘要

A method is disclosed for borehole compensation of measurements of earth formations penetrated by a borehole including differential time (.DELTA.t) measurements obtained from a borehole tool in the formation. The borehole tool includes at least one transmitter and a plurality of receivers spaced apart from each transmitter. Each transmitter generates a waveform, and the receivers are responsive to the waveform. A receiver array .DELTA.t measurement is generated for a depth interval spanned by the receivers by cross-correlating receiver array waveforms relevant to the spanned depth interval. A synthesized transmitter array .DELTA.t measurement corresponding to the spanned depth interval is generated by cross- correlating selected transmitter array waveforms. The transmitter array waveforms are selected corresponding to the spanned depth interval by identifying the receiver arrays whose transmitter locations fall within the spanned depth interval and identifying a set of waveforms from the identified receiver arrays to obtain the transmitter array waveforms. The receiver array .DELTA.t measurement is averaged with the transmitter array .DELTA.t measurement to obtain a borehole compensated .DELTA.t measurement corresponding to each transmitter. When the borehole tool includes more than one transmitter, all the borehole compensated .DELTA.t measurements corresponding to each transmitter are averaged to obtain a comprehensive borehole compensated .DELTA.t measurement.