Patent ID: 6304086
Filing Date: 2001-10-16
Classification: G01V

Abstract:
A method for evaluating the resistivity of earth formations surrounding a borehole, comprising:a) positioning a pair of transmitters T1, T2 within the borehole;b) positioning a pair of receivers R1, R2, separated from one another by a distance d, within the borehole;c) transmitting electromagnetic energy of frequency f1 from a first transmitter of the transmitter pair;d) receiving voltage data associated with the transmitted energy at the receiver pair;e) shutting off the transmission of electromagnetic energy from the first transmitter;f) transmitting electromagnetic energy of frequency f1 from a second transmitter of the transmitter pair;g) receiving voltage data associated with the transmitted energy at the receiver pair; andh) calculating the following expression to determine the formation conductivity: ##EQU48##whereV.sub.21 is the voltage data received on receiver R2 when transmitter T1 is active; andV.sub.12 is the voltage data received on receiver R1 when transmitter T2 is active.