Effect of authigenic clay minerals and carbonate cements on quality of tight sandstone reservoirs: Insight from Triassic tight sandstones in the Huaqing area, Ordos Basin, Northern China. (15th May 2022)

• Record Type: Journal Article
• Authors: Zhao, Shijie; Fu, Qiang; Fu, Jinhua; Liu, Xianyang; Li, Shixiang; Zhang, Guanyu; Teng, Ji
• Is Part Of: Journal of Asian earth sciences. Volume 229(2022)
• Publication Date: 2022-05-15
• Subjects: Tight sandstone -- Ordos Basin -- X-ray computed tomography -- Pore-throat size distribution -- Authigenic clay minerals -- Carbonate cement; Earth sciences -- Asia -- Periodicals; Sciences de la terre -- Asie -- Périodiques; Earth sciences; Asia; Periodicals; 555.05
• DOI: 10.1016/j.jseaes.2022.105099
• Languages: English
• ISSNs: 1367-9120

Abstract

Graphical abstract: Highlights: Pore and throat structure can be characterized separately by XCT scanning. Chlorite and illite produced most of the intercrystalline pores in tight sandstone. Chlorite coatings are effective in preserving the large primary pore-throat. The densification was completed by cementation instead of compaction. Tight sandstone with high chlorite is the best quality reservoir in the Ordos Basin. Abstract: As an important part of tight sandstone, authigenic clay minerals and carbonate cements have a strong influence on the densify of tight sandstone, but the details of these effects on pores and throats need be further clarified. The Ordos Basin is the second-largest sedimentary basin in China with the highest annual oil output and is characterized by tight sandstone. In this paper, the thin section, HPMI, XCT scanning and fluid inclusion homogenization temperature were combined to study the densification process of the tight sandstone in the Ordos Basin. The results show that early chlorite coating can effectively reduce further damage to the pore-throat space. But the pore-lining chlorite and illite led to reduce of the radius of intercrystalline micropores to <1 μm. After mechanical compaction, authigenic illite and the late ferrocalcite and ferrodolomite cements continued to grow and eventually complete the densification. Authigenic clay minerals and carbonate cements played contrasting role on evolving of pores and throats: tight sandstone with high chlorite showed obvious "right peak" PSD and TSD in XCT scanning with the largest number of throats, formed the best-quality reservoir; tight sandstone with high carbonate cement suggesting flat "right peak" TSD and increased the average length of throats; tight sandstone with high illite showed flat and "left shift" PSD and obvious "bimodal" TSD with the fewest number of throats, and formed the worst-quality reservoir.