Integrated Geophysical Research of the Macroscopic distribution of Pre-Cenozoic Residual Basins-A Case Study in Dagang Area

Using geophysical data to delimitate the macroscopic distribution of residual basins is one of the important techniques in residual basin oil/gas research. Taking Dagang area as an example this paper presents the method of integrated geophysical research of residual basin distribution. Based on the analysis of rock physical properties, the burial depths of gravity basement (corresponding to the bottom of Cenozoic in this area) and magnetic basement (corresponding to the top of Archaean) are determined by forward computation and inversion, then the residual thickness of pre‐Cenozoic group in the study area is calculated. The characteristics of residual basin distribution are discussed, and the prospective regions of oil/gas resources are predicted. The research result shows that the distribution of residual thickness in the study area is characterized by zoning in the east‐west direction, the belts of thickened pre‐Cenozoic group trend mostly in NE direction, indicating that the NW‐SE compressional stress in the later stage had a certain effect on the distribution. The junction area of Chengning uplift and Qikou depression has the greatest residual thickness of pre‐Cenozoic group in the study area. Northward over thrust structures exist in this area, which are beneficial for pre‐Cenozoic hydrocarbon accumulation.