New Pattern of Uplift-Depression of the Pre-Cambrian Basement in the Sichuan Basin: Constraints From Multi-Seismic Parameter Imaging

Abstract

The structural configuration of the pre-Cambrian basement in the Sichuan Basin, a highly promising region for hydrocarbon exploration, has been a subject of long-standing debate. Here, we determined the fine-scale three-dimensional seismic models of the Sichuan Basin using 187,356 high-quality P- and S-wave travel time pairs recorded by 627 recently installed seismic stations. Meanwhile, 595 petroleum wells were collected to investigate their spatial distribution associated with the basement structures. Our findings reveal two depression belts, one extending through the western regions of Chengdu, Mianyang, and Wanyuan, and another in the eastern regions of Wanzhou, Fuling, and Chishui, forming a distinctive horseshoe-shaped depression structure. Concurrently, the central and southwest regions exhibit two uplift zones, constituting an L-shaped uplift structure. Approximately 76% of the petroleum wells are situated within the L-shaped uplift structure and its slope, while around 21% of the gas wells are located in the transitional zones between the depression structures or along their edges. The development of the depression structure is attributed primarily to the complex triple collision system involving the Qinghai-Tibet block in the west, the Cathsysia block in the southeast, and the North China block in the north. Conversely, the uplift structure is mainly caused by the southeastward movement of the Songpan-Ganze block and the northwestward movement of the Cathsysia block. These new findings reveal a significant correlation between the paleo-uplift structures, the distribution of hydrocarbon resources, and the geological conditions conducive to petroleum reservoirs in the Sichuan Basin, providing valuable insights for predicting potential petroleum reservoirs.