A Multiple-Depth-of-Investigation Electromagnetic Wave Resistivity Sensor: Theory, Experiment, and Field Test Results

Abstract

Summary This paper presents theoretical, experimental, and field results for a multiple-depth-of-investigation, measurement-while-drilling (MWD), electromagnetic wave resistivity (EW) sensor. The sensor has four different transmitter/receiver antenna spacings with a phase difference and amplitude ratio at each spacing. The resultant logs provide information on the resistivity radial profile and an accurate Rt evaluation. Comparisons of field logs with wireline logs and with theoretical and experimental results show that this type of sensor can offer an extra-shallow, shallow, medium, and deep investigation depth under most logging conditions.