Geological characteristics of hydrocarbon migration along a strike fault: a case study of Shaojia Fault, Zhanhua Sag, Jiyang Depression

The ENE trending Shaojia Fault in the Shaojia Subsag, Zhanhua Sag, Jiyang Depression has been studied. We summarized some special geological conditions for hydrocarbon migration along strike faults, including strike slip properties, faults located on a structural ridge, extremely underdeveloped transport layers on both sides of a fault, sufficient oil source and underdeveloped trap, and the matching between fault end and transport layer. The above geological conditions are not likely to be present at the same time in most areas, which explains rare hydrocarbon migration along a strike fault. The relationship between bending faults in different directions, reservior (transport layer) development formation, fault combination pattern and hydrocarbon migration along a strike fault were discussed in order to summarize the favorable geological conditions for hydrocarbon migration. It was concluded that during the main migration and accumulation period in Neogene, NW trending left lateral left-step faults and NE trending right lateral right-step faults were easy to form in a tensile weak zone at the bend, and were favorable for vertical and strike migration of hydrocarbon. The contours of sand bodies presented pinnate shape, vertical "丰" shape and half pinnate and half "丰" shape toward faults. As a result, hydrocarbon could not migrate out of the fault into a carrier bed, but migrates along a strike fault. The possibility of hydrocarbon migration along a strike fault of the Shicun Fault in Dongying Sag and the Linyi Fault in Huimin Sag was discussed.