Constraints of slope break belt on oil and gas trapping−An example from the Pinghu Formation in the Kongqueting area of Pinghu Slope

Slope break belt plays critical controlling roles in the formation of complex lithologic traps. The Kongqueting area on the Pinghu slope was a typical slope break belt in terms of paleogeomorphogy. To reveal the tectonic type of the slope break and its control over sand body sedimentation, depositional facies and trapping formation process is very important for the next cycle of oil and gas exploration of the region. According to the structural position of the slope break belt and its matching relationship with depressions, there are three types of slope break belts in the study area including the high stand slope break, the middle stand slope break and the low stand slope break. According to the genetic mechanism, it can be subdivided into faulting slope-break, flexure slope break and erosional slope break. In the high stand slope breaks, the erosional one dominates, which controls the formation of depositional systems of braided river and deltaic plain as well as the erosional valley traps. The middle slope break is dominated by fault slope break and flexure slope break, which controls the formation of the depositional systems of braided river, deltaic plain and deltaic front, and the compound lithologic traps such as braided river channels and fan bodies, and the fault block-river channel laterally pinched sandbodies. The low slope break is developed along the fault steps, where composite sand bar deposits occur, forming the fault block-sand bar composite lithologic traps.