Paleogeomorphology restoration and hydrocarbon accumulation controls in the Triassic–pre-Jurassic study area

Abstract

To investigate the controls of Triassic-Pre-Jurassic paleogeomorphology on hydrocarbon accumulation, a high-resolution stratigraphic framework was established through integrated well and seismic data, with stratigraphic correlation performed. The imprint method was adopted to restore and precisely reconstruct the pre-Jurassic palaeogeomorphology in the Yanwu and Hongde areas, which enables the analysis of its control over reservoir formation. The results show that the upper layer of the Yan-9 section is used as the reference surface in the Hongde area, while the upper layer of the Yan-8 section is used in the Nanyanwu area. The thicknesses of the Yan-10 section and the Fuxian Formation are considered residual thicknesses. Based on sedimentary characteristics, structural morphology and thickness distribution of overlying and underlying strata, the palaeogeomorphology of the study area from the Triassic to pre-Jurassic can be divided into five units: incised valley, main channel, palaeoterrace, slope and interchannel mound. Ancient geomorphic structures influence sedimentation and compaction, with structural highs favoring hydrocarbon accumulation. Deep river valleys facilitate the formation of reservoirs and the transport of hydrocarbons, while simultaneously exposing the underlying rock formations and promoting rapid filling processes.