Structural and sedimentary features of Oman foreland basins and its influences on hydrocarbon accumulation

Oman orogeny that occurred at Late Cretaceous affected both passive and active continental margin depositional systems, and controlled the hydrocarbon enrichment in the Rub Al-Khali Basin and Oman Basin. In order to clarify the relationships among the Oman orogeny, deposition and hydrocarbon accumulation conditions, we summarized the tectonic evolution stages and differences, and refined the sedimentary coupling characteristics of different structural units according to the balanced cross-section recovery in several regional geological-seismic data. By analyzing cores, thin sections, Micro-CT, geochemical and seismic data, the controls of Oman orogeny on key geological elements and multi-type lithologic traps of the Cretaceous were summarized. It is concluded that, the Oman Mountains located at the northeastern margin of the Arabian Plate and evolved three stages from the Cretaceous to the Paleogene, including the late passive continental margin, the oceanic crust over-thrust, and the foreland orogeny. The tectonic system has undergone the evolution from the fault-horst to compression-torsion or thrust faults, and the strain intensity has the characteristics of weakening from north to south. The Oman foreland basin mainly affects the tectonic-sedimentation process of the foredeep-slope and backbulge zones around the Lekhwair uplift. The Cretaceous strata recorded the sedimentations of passive continental margin, active continental margin denudation, and stable subsidence. Late Cretaceous compressive stress controlled the high-quality reservoirs in the UAE and Oman and the final shaping of multiple types of traps such as reef-shoals, fault blocks, karsts and unconformities. The research work systematically sorts out the sedimentary and hydrocarbon accumulation characteristics and provides the inspiration for the forming mechanism and fine exploration of multi-types of lithologic traps.