The Morphological Characteristics of Clay Minerals in a Tight Sandstone Reservoir by Atomic Force Microscopy

Clay minerals, as one of the main components of unconventional oil and gas reservoirs, have significant implications for the evaluation of unconventional oil and gas reservoirs in terms of their fine characterization of nano/sub-nano morphological features. By using atomic force microscopy (AFM) micro-area analysis technology, the problem of secondary modification of nano-pore structure caused by the conductive film in the pretreatment process of electron microscopy was solved; it made up for the defect that electron microscopy requires the sample to be conductive and can directly observe the morphological characteristics of the sample. Here, it was observed through AFM, that in the late diagenetic stage of the tight sandstone of the Xujiahe Formation in western Sichuan, some clay minerals developed parallel stepped stripes, with a large number of nano-pores formed at the concave angles on both sides of the steps, which were the main components of inorganic pores. Secondly, clay minerals had the same diagenetic evolution sequence, but their crystal morphologies were different, indicating that there was a spatial coupling relationship between their morphological features and diagenesis. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202404040075.