WELL LOGGING METHOD AND APPARATUS PROVIDING MULTIPLE DEPTH OF INVESTIGATION USING MULTIPLE TRANSMITTERS AND SINGLE RECEIVER PAIR

摘要

AN APPARATUS AND METHOD FOR DETERMINING FORMATION RESISTIVITY AT A PLURALITY OF RADIAL DISTANCES FROM AN EARTH BOREHOLE USES A SINGLE RECEIVER PAIR (R1, R2) AND A PLURALITY OF ELECTROMAGNETIC ENERGY TRANSMITTERS (16, 18, 20) SEQUENTIALLY SPACED ALONG THE APPARATUS FROM THE RECEIVER PAIR, SUCH TRANSMITTERS BEING SEQUENTIALLY PULSED AT APPROXIMATELY 1 - 2 MHZ EACH TO PROVIDE TIME SEPARATION BETWEEN THE PULSING OF THE PLURALITY OF TRANSMITTERS. THE CLOSEST SPACED TRANSMITTER (16) IS SPACED A PREDETERMINED DISTANCE FROM THE CLOSER RECEIVER (R1) TO MAKE THE DEPTH OF INVESTIGATION OF THE CLOSEST TRANSMITTER (16) ESSENTIALLY INDEPENDENT OF FORMATION RESISTIVITY. ALTERNATIVELY, A SINGLE TRANSMITTER IS SPACED A PREDETERMINED DISTANCE FROM THE CLOSER RECEIVER TO MAKE THE DEPTH OF INVESTIGATION OF SUCH TRANSMITTER ESSENTIALLY INDEPENDENT OF FORMATION RESISTIVITY.(FIG 2)