Development Mechanism and Identification Methods of subtle Strike-slip Faults in the Neogene-Quaternary of Bohai Sea

There are a large number of "subtle strike-slip faults" in the Neogene-Quaternary strata of the Bohai Sea that are difficult to identify from seismic data. They have steep fault planes, intermittent distribution, and small fault throw. In the process of oil and gas exploration, the failure of subtle fault characterization often leads to trap failure. Therefore, it is urgent to re-understand the subtle strike-slip faults and guide the effective characterization from the perspective of fault development mechanism. Based on the tectonic background of the Neogene-Quaternary in the Bohai Sea and three-dimensional seismic data, the development mechanism and identification method of subtle strike-slip faults were explored. The results showed that the subtle strike-slip faults in the Neogene-Quaternary in the Bohai Sea were displacement partitioning strike-slip faults, which were developed under the background of oblique extension of pre-existing faults, and were not directly controlled by the basement strike-slip faults; There is a specific relationship among the angle α between the pre-existing boundary fault and the oblique extension direction, the angle θ between the pre-existing boundary fault and the extension faults, and the probability P of displacement partitioning strike-slip. This principle can be used to determine whether the subtle strike-slip fault is developed, and has achieved good application results. This study has clarified the development mechanism and identification method of subtle strike-slip faults in the Neogene-Quaternary period in the Bohai Sea, providing important guidance for oil and gas exploration.