Two distinct strike-slip fault networks in the Shunbei area and its surroundings, Tarim Basin: Hydrocarbon accumulation, distribution, and controlling factors

Over the last few decades, significant advances in acquisition of new three-dimensional seismic data sets have revealed the exis-tence of a spectacular strike-slip fault system consisting of mul-tiple fault networks developed across the northern Tarim Basin. These strike-slip fault networks are of significant importance to petroleum exploration because of their dual roles as conduits for hydrocarbon migration and fault-controlled paleo-karst reservoirs. In this study, two representative strike-slip fault networks are selected for detailed analysis to understand their control on hydrocarbon accumulation and distribution. In the "X-shaped" TP39-TP29 fault network developed in the Tabei uplift, high-production wells are distributed mainly along the first-order north-northeast-oriented fault TP39, partic-ularly in the pull-apart structures. This is attributed to the reacti-vation of fault TP39 in the late Hercynian and Himalayan orogenies when oil accumulation mainly occurred, whereas the north-northwest-striking faults remained inactive. In the TP39-TP29 fault network, areas of higher fault intensities (fault abundance) generally coincide with the distribution of high-producing wells except those located distantly from fault TP39. In the SB5-SB1 fault network, the divergent strike-slip fault (SB1) has a higher average well performance than the convergent strike-slip fault (SB5). Unlike the TP39-TP29 fault network in which fractured paleokarst reservoirs are widely developed in the Shunbei area where widely developed kar- stification is absent, brittle fault zones including fault breccia and fractures in the tight Ordovician carbonates provide permeable conduits and space for transporting hydrocarbon and storage, respectively. Releasing bends concentrating dilation breccias are characterized by a higher degree of hydrocarbon accumulation than restraining bends and simple strike-slip segments.