Fault Characteristics and Reservoir Control Model of Steep Slope Belt in the Eastern Zhangwu Area

Oil and gas exploration in the Zhangwu Fault Depression has been stagnant for many years, but the success of the Well ZW13 in 2019 has revived hope in the area. On the basis of the existing data and the background of regional tectonic evolution, the faults in the eastern steep slope zone of the Zhangwu Fault Depression have been restudied, which is expected to further explore the control effect of fault evolution on reservoir distribution. Beginning with the fault combination pattern analysis, methods of artificial interpretation projection and fault spatial activity analysis were used to discuss the spatial distribution and activity characteristics of boundary faults. Combining with forming mechanism of basin, the basin prototype property of "Sinistral Rotation transformation-extensional Basin" in the Zhangwu Fault Basin has been put forward. The boundary fault (Zhangwu Fault) is characterized by sinistral rotation right-step type of subsection activities. The center of the subdepression in the basin that controlled by the Zhangwu Fault and the secondary faults in the steep slope zone is separated and diagonally distributed. From the above understanding, a reservoir development model of "transformation sand control" is proposed. Combining with the successful exploration examples, Jiufotang Formation in the transformation and Yixian Formation in the upthrown side in the eastern steep slope zone have been suggested as the main formations for the next three-dimensional exploration project.