Secondary migration of petroleum along syncline axes: a case study of the southern Kuqa Foreland Basin

Tracing petroleum migration pathways for petroleum exploration in a sedimentary basin is challenging. Paleo-uplifts are generally considered to represent the primary migration directions of petroleum. Here we propose a model for the Kuqa Foreland Basin, in which petroleum migrates along the axes of synclines between paleo-uplifts, based on an integrated analysis of seismic, geochemical, and production data. Interpretation of detailed seismic data indicates that petroleum is unlikely to migrate to the paleo-uplifts because of their relatively low positions, fault disruptions, or a lack of Mesozoic reservoirs. Geochemical parameters, including the ratios of alkyl dibenzothiophenes and the gas wetness parameter, show that petroleum maturity gradually decreases along the axes of synclines between paleo-uplifts from northeast to southwest. Petroleum production data and gas/oil ratios also show decreasing trends from northeast to southwest. This evidence suggests that petroleum is likely to migrate along the axes of the synclines between the paleo-uplifts from northeast to southwest. This study not only enhances the scientific understanding of secondary migration, but also may be useful to guide petroleum exploration in the southern Kuqa Foreland Basin.