Reservoir mapping using the high frequency EM method: Taob oil field case study
This paper is an introduction to the high frequency electromagnetic (EM) method and its application. The method uses multiple sources (natural and artificial) and five electromagnetic tensors are recorded. After data processing, resistivity and phase anomalies can indicate reservoir boundaries and favourable areas for drilling. The method has been applied to the Taob oil field and the results are presented in the paper. In this case, the oil-bearing area was mapped accurately and another prospective area was discovered. Many successful cases in China have demonstrated that the high frequency EM technique can be widely used for reservoir mapping and indications of prospective areas. The setting The Taob oil field is located in the Songliao Basin, northeast China, where 2D seismic data have been acquired. The target formation K1 2 is shallow (300-400 m) and regionally eastward dipping (Fig. 1). It is especially worth mentioning that the recently discovered overthrust in the western blocks, which trends northeastwards, acted as a seal for the oil and gas migrating from the central depression, and that oil is present in several faulted structural noses associated with the eastern side of the overthrust. This has made commercial oil production possible on the regional slope. The traps delineated in the area are mainly structural. Study of this shallow reservoir shows that there might be many other lithological traps and overlap traps, which is a challenge for seismic prospecting. In order to probe the non-structural traps economically, the high frequency EM technique was adopted in this case and the results show its good effect.