Detecting Favorable Oil and Gas Targets with Time-frequency Electromagnetic Method – Case Studies

Abstract

Artificial source and axial dipole are used for time-frequency electromagnetic (TFEM for short hereinafter) acquisition. TFEM data in both frequency domains and time domains are simultaneously acquired and studied. TFEM method is based on physical property differences between hydrocarbon-bearing reservoir and non-hydrocarbon-bearing host, in other words, TFEM technique makes use of the characteristic that hydrocarbon-bearing traps cause resistivity anomaly and polarization anomaly, as well as that resistivity and polarization are sensitive to variation on porosity and permeability. High-power artificial source is used to excite underground layers to produce the EM responses, through which resistivity and polarization anomalies caused by reservoirs can be directly detected. TFEM technique has been used for thousands of kilometers’ profile survey and verified by dozens of exploration wells. Extensive attention has been paid to TFEM survey from oil companies. In this paper, we compare our study on different reservoir types (porous-reservoir, fracture-reservoir, blocked-reservoir) and on different trap types (structural traps, stratigraphic traps, lithologic traps) with TFEM technique, providing references for better application of the method.