四川盆地西缘新元古界张性结构特征及勘探意义OA

The Sichuan Basin is rich in oil and gas resources,with its basement structure controlling hydrocarbon distribution from the ultra-deep Sinian to the shallow Jurassic Strata.With the application of ultra-deep gravity-magnetic-electric-seismic joint exploration techniques since 2010,the Neoproterozoic extensional structures in the Sichuan Basin has been continuously confirmed through exploration.Based on the high-resolution gravity-magnetic-electric data and"double-high"(high fidelity and high resolution)seismic data,combined with the outcrop observations along the basin margin and borehole data from 8 wells drilled into the Sinian Doushantuo Formation,a comprehensive interpretation study is carried out.It is proposed that the Sichuan Basin has developed"western Sichuan rift",which has mainly experienced three evolutionary stages from a rift to a depression.Stage 1:Nanhua rift stage,which was dominated by multiple near NE-trending horsts and grabens.Stage 2:the intra-cratonic depression stage happened during the deposition of the Sinian Doushantuo Formation,which was formed by merging the Northwest Sichuan Depression and the Central Sichuan Uplift.Stage 3:intra-cratonic depression stage happened during the deposition of the Sinian Dengying Formation,forming a nearly SN-trending extensional trough which opens towards northwest.Further study shows that strike-slip faults could easily occur during the evolution of the western Sichuan rift.The rift provides conditions for hydrocarbon accumulation in the Nanhua-Sinian Strata where oil and gas can be generated by lower strata,transported by faults and stored by upper strata.The Nanhua-Sinian petroleum system in the western-central Sichuan area is a new potential exploration area.