Abstract：

The Yangchungou area is a key replacement area for shale gas exploration in eastern Sichuan in China. Its main control fault, the Yangchungou fault, is an important structure affecting shale gas accumulation in the area, but there are few previous studies, resulting in a low degree of overall research. In order to clarify the structural deformation characteristics of the Yangchungou fault and its geological significance, based on the latest interpretation of three-dimensional seismic data, the geometric characteristics of the Yangchungou fault are described. And we analyze its formation mechanism through fault properties and activity period. Based on this, the relationship between the Yangchungou and Zunyi faults and its influence on shale gas accumulation are discussed. The results show that: (1) The Yangchungou fault is mainly characterized by a planar thrust structure from east to west. The surface outcrop data show characteristics of sinistral compression and torsion. In addition, the Yangchungou fault is characterized by multiple superimposed and nearly parallel thrust slip fault zones along the Silurian and Cambrian, which control the fault development anticline of the middle and shallow deformation layers. (2) The Yangchungou fault is not a part of the Zunyi fault. The structural deformation characteristics of the Yangchungou and Zunyi faults are very different. They show completely different structural styles in seismic profiles. Therefore, the Yangchungou fault and the Zunyi fault are not two parts of the same fault. (3) The Yangchungou fault formed a small fault in a nearly north-south direction during the early Xuefeng orogeny, which caused the Zunyi fault to undergo left lateral reverse washing and sliding. The current form of the Yangchungou fault was formed in the late stage by the reverse compression torsion of the arc-shaped folded wing from east to west. Therefore, the Yangchungou fault has undergone uneven contraction from the Late Jurassic to the Late Cretaceous and reverse sliding from east to west in the Late Cretaceous. (4) The Yangchungou fault has formed the Yangchungou anticline and a complex fracture network. The Yangchungou anticline reduces the depth of shale burial, slows down the evolution of shale maturity, and the complex fracture network increases the storage space, but does not seriously damage the preservation conditions. Both are conducive to the migration and accumulation of shale gas into reservoirs. The development of high and steep strata and compressional and torsional faults can have a destructive effect on shale gas reservoirs. The results of this study can help for better understanding the basin-mountain coupling process and shale gas exploration.

Key words：Yangchungou fault; double reverse thrust detachment; genetic mechanism; shale gas exploration; Sichuan Basin

Received： 2024-06-21

Corresponding Authors：thu@cup.edu.cn

Cite this article：叶欣, 胡涛, 闫思雨, 刘成林, 姜福杰. 断裂构造变形作用下的页岩气差异富集响应——以川东阳春沟断裂为例. 石油科学通报, 2024, 09(05): 713-723 YE Xin, HU Tao, YAN Siyu, LIU Chenglin, JIANG Fujie. Differential enrichment response of shale gas under the deformation of fault structures: A case study of Yangchungou fault in eastern Sichuan Basin. Petroleum Science Bulletin, 2024, 09(05): 713-723.

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