Gain compensated directional propagation measurements

摘要

A method for obtaining gain compensated electromagnetic logging while drilling propagation measurements includes rotating an electromagnetic logging while drilling tool having first and second transverse transmitter antennas whose moments are orthogonal to one another and first and second transverse receiver antennas whose moments are orthogonal to one another in a subterranean wellbore. Electromagnetic voltage measurements are acquired from the first and second transverse receiver antennas while rotating. The acquired voltage measurements are processed to compute harmonic voltage coefficients. Ratios of selected ones of the harmonic voltage coefficients are in turn processed to compute a gain compensated quantity including a transverse term.

主权项

1. A method for making downhole electromagnetic logging while drilling measurements, the method comprising
(a) rotating an electromagnetic logging while drilling tool in a subterranean wellbore, the logging tool including first and second transverse transmitter antennas whose moments are orthogonal to one another and first and second transverse receiver antennas whose moments are orthogonal to one another; (b) acquiring a plurality of electromagnetic voltage measurements from the first and second transverse receiver antennas while rotating in (a); (c) processing the voltage measurements acquired in (b) to compute harmonic voltage coefficients; (d) processing a ratio of the harmonic voltage coefficients to compute a gain compensated quantity including a transverse term, wherein the transverse term is one an xx direct coupling impedance, a yy direct coupling impedance, an xy cross coupling impedance and yx cross coupling impedance or a combination thereof.