LAUSR

Abstract The slope zone of fault basin has a large area and high hydrocarbon potential. Its relatively highly scattered reservoirs and vastly different accumulation characteristics make it difficult to accurately determine the main controlling factors of hydrocarbon accumulation. To solve this problem, we adopt the 3rd member of the Funing Formation (Ef3) in the slope zone of the Qintong Sag as an example to identify the main controlling factors of hydrocarbon accumulation in the slope zone of the Paleogene continental fault basin. The results reveal that there are two critical intervals for Ef3 in the Qintong Sag slope zone, namely, the Late Paleogene to the Early Neogene (23.2–20 Ma) and the Late Neogene to the Early Quaternary (2 Ma until now), and the crude oil comes from the source rock of the second member of the Funing group related to the slope barrier and the inner slope zone. Instead of migrating directly into the traps in the slope zone, three main paths of hydrocarbon migration were developed: First from southwest to northeast and then from northeast to southwest; From northeast to southwest; From west to east directly. Oil and gas migrated along the sand body in the northeast and southwest directions and bypassed by the central antithetic fault terrace, thus forming the mode of accumulation along the fault edge.