Wide Field Electromagnetic Method for Shale Gas Exploration in Southern China: A Case Study

Southern China is a favorable area for shale gas exploration and development, however the steep terrain and complex geological structures make development difficult. Using logging data, seismic data and Wide Field Electromagnetic Method (WFEM) data, this paper studies the distribution of mudstone and shale and assesses the effects of different geophysical techniques used in the Chengkou (CK) block, in the Sishang Chengkou area, which has typical shale gas exploration conditions found in Southern China. The results indicate that while a requirement for obtaining precise, high resolution lithologic information, logging has limited value for obtaining structural information in the CK block. Logging is most useful for verifying the results of seismic and WFEM studies. Currently available seismic methods were also found to be unreliable for making layer selections and designing a fracturing plan due to the complex structure and resulting high signal-to-noise ratio (S/N). WFEM methods did provide information about strata distribution, geological structures, and fracture zones to reveal the prospect of hydrocarbons. WFEM was found to have great value for shale gas exploration and development in this geologic environment and allowed for the identification of a large volume with high gas yield potential.