Development and cycle control of strike-slip transition zone in Liaobei area of Bohai Sea

Combined with previous research results based on three-dimensional seismic data and drilling data, the development characteristics of strike-slip faults in the northern Liaoning, NE China, was analyzed in detail, the macro identification and fine characterization of strike-slip transition zone were completed, and the role of strike-slip transition zone in controlling the development circling was summarized. Results show that the Dongying fault system as a whole shows clear dextral strike-slip properties. Three NE-trending strike slip faults are developed, and the fault assemblages present typical strike-slip structural styles, such as feather, echelon, horsetail, and flower. In terms of mechanical properties of strike-slip transition zone, they were divided into two categories: pressurization type and depressurization, and each could be subdivided into two sub-categories according to the spatial distribution relationship of faults: single-branch bending type and dual-branch superposition type. The first type shows that the plane of single strike-slip fault presents "S" type deformation, and the second type shows dextral right-stepped arrangement or dextral left-stepped arrangement. The pressurized and depressurized strike-slip transition zones controlled the development of fault anticline trap and fault block structural trap, respectively; and the former trap has greater exploration potential than the latter. This study enriched the structural system of strike-slip transition zone, filled the gap in the study of strike-slip transition zone in the northern Liaoning, and shall be able to guide the oil and gas exploration in the Tanlu strike-lip fault zone in the Bohai Sea region.