Structural characteristics and storage control function of the Shun I fault zone in the Shunbei region, Tarim Basin

Abstract

The Shunbei region, situated in the Tarim Basin, exhibits exploration potential. Previous exploration experience suggests that the Shun I strike-slip fault zone plays an important role in reservoir formation and hydrocarbon accumulation. In this study, based on the interpretation of three-dimensional seismic data, the structural characteristics of the Shun I strike-slip fault zone were identified. This study revealed that the Shun I strike-slip fault zone is characterized by vertical stratification, plane segmentation, multiple evolution staging, and heterogeneity of storage control. Influenced by tectonic activities during five periods, namely the early Caledonian, middle Caledonian, late Caledonian-early Hercynian, late Hercynian, and Indosinian-Himalayan periods, the Shun I strike-slip fault zone mainly developed high-angle strike-slip faults and en echelon normal faults during the Paleozoic. The Mesozoic–Cenozoic developed primarily small-scale extensional faults without spatial coupling with underlying strike-slip faults. The Shun I strike-slip fault zone consists of both hydrocarbon migration pathways and hydrocarbon traps. High-quality reservoirs generally develop along faults. Fractures in the damage zone of the Shun I fault control the formation of reservoir space. The Shun I strike-slip fault zone exhibits distinct segmentation characteristics. The Shun I strike-slip fault zone can be divided into nine segments of three types: vertical, pull-apart, and push-up. The discontinuity along the strike of the Shun I strike-slip fault zone partially controls the heterogeneity of the reservoir distribution, thus affecting reservoir connectivity. The nature of different segments of the strike-slip fault zone controls the scale and quality of reservoir development and restricts the formation of oil and gas reservoirs. Three types of oil control models were established for the Shun I strike-slip fault zone. Our findings indicate that the central main fault plane of the vertical segment pattern is the richest in hydrocarbons. Oil and gas accumulation along the fault plane of the flower structure in the pull-apart or push-up segments.