中上扬子地区下寒武统富有机质页岩吸水特征及对页岩气勘探的指示意义

以中上扬子地区下寒武统富有机质页岩为研究对象，分别选取位于寒武系页岩气勘探突破区的湖北宜昌和四川威远2个地区的3个钻井/露头剖面（宜昌WPZK001井剖面、长阳露头剖面和威远W001?4井剖面）和目前勘探失利区的2个典型剖面（贵州开阳剖面和重庆酉阳剖面）共37件样品，开展岩石小柱体的吸水实验，并与四川盆地志留系龙马溪组富有机质页岩进行对比研究。结果表明：寒武系页岩气勘探突破区的下寒武统水井沱组/筇竹寺组富有机质页岩与四川盆地志留系龙马溪组富有机质页岩相似，其饱和吸水量主要受有机碳含量和石英含量的控制，表现出较好的正相关关系，而寒武系页岩气勘探失利区的下寒武统牛蹄塘组富有机质页岩的饱和吸水量则与黏土矿物和碳酸盐矿物含量表现出弱的正相关关系，与有机碳含量和石英含量均无明显相关关系。这不仅指示了研究区下寒武统富有机质页岩发育孔隙网络特征，特别是有机质孔隙的发育，存在显著差异,同时也为从富有机质页岩矿物组成及其成因来源与孔隙发育耦合机制方面来探讨寒武系页岩含气性变化提供了新的研究思路。

The characteristics of water uptake for the Lower Cambrian shales in Middle-Upper Yangtze region and its implication for shale gas exploration

In this study, 37 samples of Lower Cambrian shale collected from different sections involving shale gas exploration-breakthrough areas (Well WPZK001 from Yichang City, Changyang section from Hubei Province, and Well W001-4 from Weiyuan County) and -failure areas (Kaiyang section from Guizhou Province and Youyang section from Chongqing City) both in the Middle-Upper Yangtze region were investigated by water uptake experiments, with a similar comparative study of Silurian Longmaxi shale samples in the Sichuan Basin. The comparative results showed that the water uptake content for the Lower Cambrian organic-rich shale samples from shale gas exploration-breakthrough areas are primarily controlled by TOC content, showing a positive correlative increase of water content and TOC content, which is similar to that of Silurian Longmaxi organic-rich shale samples in the Sichuan Basin. In contrast, the water uptake content for the Lower Cambrian organic-rich shale samples from shale gas exploration-failure areas generally showed a positive correlation with clay and carbonate contents, and there is no correlation with TOC content. It implies that the characteristics of pore network in the Lower Cambrian organic-rich shales from Middle-Upper Yangtze region, especially the development of organic matter-hosted pores, display significant differences regionally. Importantly, it provides a newly-developed strategy on the study of gas content variation in Cambrian shale from Middle-Upper Yangtze region by investigating the coupling mechanism of pore development and mineral composition as well as origins in organic-rich shales.