Based on gravity and magnetic data and combining with data from drilling, geology and seismography, eight basement faults are inferred in the research area. Existing oil fields are mostly distributed on both sides of the basement faults in strike trend. Trial gas production from exploration wells is closely related to the distribution of the basement faults. “Hidden” activities of the basement faults resulted in the structural fissures vertically developed in sedimentary cover. The fissures could be channels for oil and/or gas migration and also increase the porosity and permeability of oil reservoirs, which would be pivotal in oil/gas distribution and productivity of oil reservoirs in the studied area.