Facies and controls of the Paleocene-Eocene shelf deposition in rimmed platform in offshore Indus Basin

Due to the lack of drilling data and poor quality of seismic data, research on the types and evolution of the Paleocene-Eocene shallow-water shelf carbonate facies in rimmed platforms in the Indus Fan Offshore Basin is relatively weak, which seriously restricts the evaluation on hydrocarbon resource potential in this area. Based on the single-well facies analysis of the deep-water Well Pak G2-1 and combined with the geological data of the Sui Gas Field in the adjacent Indus Basin with the reference to the seismic facies plates of typical rimmed platforms such as the Sichuan Basin, we systematically calibrated and interpreted the newly collected 2D seismic data in the shallow-water shelf of the study area. Results show that: (1) Four typical seismic reflection patterns were identified within the shallow-water shelf area, based on which the sedimentary facies were classified into three major zones: the open platform, platform margin, and foreslope; and each zone can be further subdivided into several subfacies. (2) The evolution of the rimmed platform can be divided into three stages, which was jointly controlled by paleogeomorphology and relative sea-level changes, and at last Eocene entered a declining phase without complete termination. (3) The platform-margin reef facies is a favorable zone of high-quality reservoirs. This study provided a geological basis and reference for further hydrocarbon exploration in the offshore Indus Basin.