Patent ID: 8736271

Claim:
A method for making resistivity measurements of a formation surrounding a borehole using a tool comprising first and second pairs of spaced antennas, the pairs being separated along a tool body, the method comprising: i) positioning the tool body in the borehole so that the first pair of antennas is at a predetermined location in the borehole; ii) operating one of the second pair of antennas to induce a current in the formation surrounding the borehole; iii) measuring the voltage created by operation of the antenna; iv) measuring axial currents on the body at the first pair of antennas; v) moving the tool body along the borehole so that the second pair of antennas is at the predetermined location; vi) operating both of the second pair of antennas to induce currents in the formation surrounding the borehole; vii) measuring the voltages created by operation of the antennas; viii) measuring the axial currents on the body at one of the first pair of antennas as a result of operation of the second pair of antennas; and ix) determining the resistivity of the formation using the voltage and current measurements obtained; wherein step ix) comprises: calculating a first conductance of the formation using the measured voltage created by operation of the antenna and the measured axial currents on the body at the first pair of antennas; calculating a second conductance of the formation using the measured voltages created by operation of the antennas and the measured axial currents on the body at one of the first pair of antennas as a result of operation of the second pair of antennas; calculating a compensated conductance of the formation using the first and second calculated conductances of the formation; and calculating the resistivity of the formation using the calculated compensated conductance of the formation.