Structural characterization and hydrocarbon prediction for the SB5M strike-slip fault zone in the Shuntuo Low Uplift, Tarim Basin

Abstract

Newly discovered superdeep marine carbonate reservoirs with burial depths of more than 7000 m are found in the Shuntuo Low Uplift, Tarim Basin, China. Previous exploration experience indicates that strike-slip faults in these deposits played a key role in reservoir formation and hydrocarbon accumulation. This paper describes the structural and hydrocarbon characteristics of the SB5M strike-slip fault zone in the Shuntuo Low Uplift based on the study of high-quality 3-D seismic volumes and drilling data. The SB5M fault is a repeatedly reactivated strike-slip vertical fault zone. In the Paleozoic strata, the SB5M strike-slip fault zone is composed of sub-vertical strike-slip faults in the deep layer, a graben structure in the middle layer, and en-echelon normal faults in the shallow layer. The deep, middle and shallow faults developed sequentially at different times and formed as a result of three-stage evolution: the Middle Caledonian, Late Caledonian, and Middle-Late Hercynian. Fracture networks formed by repeated fault activity provided pathways for karst flow and hydrocarbons, which are conducive to the formation of fracture–cavity reservoirs. Due to the fault damage zone-fault core transition and the complex structural features, the reservoirs controlled by the SB5M strike-slip fault zone feature strong heterogeneity. The data sets presented and evolution models established in this paper provide important data for the exploration and development of the SB5M strike-slip fault zone and represent references for structural analysis and hydrocarbon exploration of strike-slip fault zones in the Tarim Basin and elsewhere.