Abstract Both the characteristics of lithofacies and tectonic movements are important factors in controlling the development, destruction, and preservation of pores in shale reservoirs. However, the main factors that control the structure of shale pores are complex and highly disputed, restricting the understanding of the mechanisms that lead to the accumulation of shale gas. In this study, mineral composition and geochemical analyses, high resolution field emission scanning electron microscopy (FE-SEM), and low-pressure gas adsorption (N2 and CO2) were conducted to evaluate the pore systems of different types shale in the Jiaoshiba area, Sichuan Basin. A total of three shale groups, including silica-rich high production shales, clay-rich low production shales, and silica-rich low production shales were identified on the basis of lithofacies and gas-bearing characteristics. The highest values of TOC, pore volume, and specific surface area are found in the silica-rich high production shales, with an average of 4.182%, 33.04 × 10−3 cm3/g, and 38.71 m2/g, respectively. The total pore volume and specific surface area in the clay-rich low production shales are 19.85% and 28.62% lower than that of silica-rich high production shales. This suggests that the types of lithofacies have a more prominent influence on the specific surface area of the shales, while the pore volume plays a smaller role. However, the pressure in silica-rich low production shales is often released due to strong tectonic deformation. The OM pores in the silica-rich low production shales therefore tend to be both compressed and closed, with low surface porosity and of round shape. The total pore volume and specific surface area of silica-rich low production shales are 34.63% and 22.0% lower than that of the silica-rich high production shales. This indicates that tectonic movement has a significant influence on the shale pore volume, while specific surface area has a smaller influence.

中文翻译：

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四川盆地焦石坝页岩气田高低产能井页岩孔隙结构特征：以岩相为主还是保存条件？

摘要 岩相特征和构造运动是控制页岩储层孔隙发育、破坏和保存的重要因素。然而，控制页岩孔隙结构的主要因素复杂且争议较大，制约了对页岩气成藏机理的认识。本研究通过矿物成分和地球化学分析、高分辨率场发射扫描电镜（FE-SEM）和低压气体吸附（N2和CO2）对焦石坝地区不同类型页岩的孔隙系统进行评价，四川盆地。共三个页岩组，包括富硅高产页岩、富粘土低产页岩、根据岩相和含气特征确定了富含二氧化硅的低产页岩。TOC、孔隙体积和比表面积的最高值出现在富含二氧化硅的高产页岩中，平均值分别为 4.182%、33.04×10-3 cm3/g 和 38.71 m2/g。富粘土低产页岩的总孔容和比表面积比富硅高产页岩低19.85%和28.62%。这说明岩相类型对页岩比表面积的影响较为突出，而孔隙体积的影响较小。然而，由于强烈的构造变形，富含二氧化硅的低产页岩中的压力经常被释放。因此，富含二氧化硅的低产量页岩中的 OM 孔隙往往被压缩和封闭，具有低表面孔隙率和圆形。富硅低产页岩的总孔容和比表面积比富硅高产页岩低34.63%和22.0%。这表明构造运动对页岩孔隙体积影响显着，而比表面积影响较小。