Characteristics of the Cambrian Shuijingtuo shale reservoir on Yichang Slope, western Hubei Province: a case study of well EYY 1

The characteristics of shale reservoirs on the Yichang Slope in the western Hubei Province were studied using organic geochemistry, mineral X-ray diffraction, field emission scanning electron microscopy and nuclear magnetic resonance methods on black shale samples collected from the Cambrian Shuijingtuo Formation in the well EYY 1. Shale in the study area is mainly composed of quartz, clay minerals and carbonates with high calcium and low siliceous contents. From bottom to top, the contents of clay minerals and carbonates gradually decrease, while the content of quartz gradually increases. Shale porosity has a positive relationship with TOC content, especially in the section with a TOC content higher than 2%. Micro pores and small pores are abundant in the shale. Small pores and meso pores contribute significantly to porosity. The contribution of pores in brittle minerals to the matrix porosity of shale is stable, while the contribution of organic pores and interlayer pores in clay minerals are respectively changing relative to their contents, which means that the contribution of organic pores increases with depth and pores in clay minerals decrease gradually.