The impacts of diagenetic facies on reservoir quality in tight sandstones

Open Geosciences

Ren Dazhong¹  Li Rongxi¹  Liu Dengke²  Sun Liang³ 

[1] School of Earth Science and Resources, Chang’an University, Xi’an 710054, China;Shaanxi Key Laboratory of Advanced Stimulation Technolgy for Oil & Gas Reservoirs, College of Petroleum Engineering, Xi’an Shiyou University, Xian 710021, China;Xi’an Geological Survey Center, China Geological Survey, Xi’an 710054, China;

关键词: diagenesis;    pore structure;    diagenetic facies;    tight sandstone;    yanchang formation;    ordos basin;   

DOI  :  10.1515/geo-2020-0174

来源: DOAJ

【 摘 要 】

The impact of diagenetic minerals and the characteristics of pore structures on reservoir qualities has been studied separately in the past years. However, the difference in the reservoir quality with different pore structures and having same or similar content of diagenesis minerals has not been ascertained. In this study, based on the core samples derived from Chang 6 member in the Ordos basin, various tests were performed to examine the sandstone diagenesis and investigate the pore structure. The results showed that there were five diagenetic facies by diagenetic and pore structure analyses, and the best reservoir quality rocks were found to have relatively low percentage of illite, carbonate cement, pore-filling chlorite, authigenic quartz, and relatively high proportion of intergranular pores. Smectite-to-illite reaction and chemical compaction were main sources for quartz cementation at 60–120°C, and carbonate content was found to increase toward source rocks. The porosity depth trends significantly affected the diagenetic facies. The diagenetic and the pore structure pathways of various diagenetic facies were reconstructed by integrated petrographic, mineralogical, and pore system data. This study provides insights into the porosity evolution and diagenetic pathways of various diagenetic facies of tight sandstones, and the influence of diagenesis minerals and pore structures on their reservoir quality.

【 授权许可】

Unknown