Fault Transportation and Hydrocarbon Accumulation in Offshore Indus Basin

According to the geotectonic analysis and seismic data interpretation, the Offshore Indus Basin is the extension of the Lower Indus Basin in the sea area, with a double-layer structure of "lower fault and upper depression" similar to that of the Lower Indus Basin in the land area. That is, the Mesozoic is a fault basin and the Cenozoic is a depression basin. On the 2D seismic profile, the Mesozoic strata are characterized by many faults, large fault throw, steep dip angle and the development of transport system. There is a great difference between the shallow water area of the northern continental shelf and the deep water area of the southern part of the Cenozoic strata. In the northern part, there are more gravity slumping faults, larger fault throw, and more developed transport systems, while in the southern part, there are fewer faults, smaller fault throw, and less developed transport systems. By comparing and analyzing the small normal faults in the passive continental margin basin of Guyana, South America, and their reservoir forming models, it can be inferred that there may be many "invisible" normal faults with small fault throw, large density and steep dip angle developed in the Cenozoic slope break area of the offshore Indus Basin. In addition, in the strike slip area of Murray Ridge in the west of the basin, the Mesozoic and Cenozoic fault transport systems are developed. The results of sea land correlation and offshore drilling core analysis show that there may be three sets of widely distributed source rocks in the Offshore Indus Basin, which are Cretaceous, Paleo-Eocene and Lower Miocene mudstones. According to comprehensive analysis, the formation of oil and gas reservoirs in the Offshore Indus Basin is mainly controlled by Mesozoic large fault transportation, Mesozoic-Cenozoic fault relay transportation, Cenozoic collapse fault transportation and "hidden" fault transportation. The types of oil and gas pools may mainly include Mesozoic "self generated and self stored" or "side generated and side stored", Cenozoic "lower generated and upper stored" in the north and east of the basin, and "lower generated and upper stored" and "self generated and self stored" in the west of the basin.