We found a match
Your institution may have rights to this item. Sign in to continue.
- Title
Carbon and oxygen isotopes and molecular fossil characteristics of unconventional gas reservoirs in Permian Maokou Formation, West Chongqing, Sichuan Basin.
- Authors
Cheng, Qingsong; Liang, Xing; Shu, Honglin; Li, Weimin; Ma, Liqiao; Xu, Zhengyu; Wang, Jinsong; Zhang, Chao; Ji, Yubing; He, Yu; Shi, Yangzhi; He, Fangyu
- Abstract
The well DB1 in West Chongqing area encountered unconventional gas in the first member of Maokou Formation (P1m1); therefore, the P1m1 core was systematically sampled and analyzed. Based on normal porosity–permeability, organic carbon, pyrolysis, and Vitrinite reflectance analysis, seven samples were selected for rock and ore identification, element analysis, carbon and oxygen isotope analysis of carbonate rocks, and GC–MS analysis of soluble organic matter. The results of organic geochemical analysis show that P1m1 carbonate rocks have high organic matter abundance and are in an over mature stage, and a large amount of natural gas has been formed. The petrophysical property analysis results show that P1m1 is an ultra-low porosity and permeability reservoir. In general, P1m1 is a set of unconventional carbonate source rock gas reservoirs. The results of rock and ore identification and carbon and oxygen isotope analysis indicate that there are talc and fluorite minerals of hydrothermal origin in P1m1 carbonate rocks, and the carbon and oxygen isotope composition of carbonate rocks is similar to that of hydrothermal dolomite in Chuanzhong area.. The GC–MS analysis shows that P1m1 carbonate rock exhibits abnormal molecular fossil assemblages, such as N-alkanes with even carbon dominance, Isoalkanes with even carbon dominance iC22+, iPC21+ long chain Isoprenoid alkanes, abnormally high abundance Hopane, relatively high abundance C29 regular sterane, and high abundance sulfur compounds. These molecular fossil evidence indicates that the P1m1 sedimentary environment has strong reducibility, and the water contains a large amount of H2S and sulfate. At the same time, a large number of chemoautotrophic bacteria and archea, heterotrophic bacteria and archea, and some hydrothermal animals jointly formed the hydrothermal ecosystem of P1m1, forming a large number of hydrocarbon generating parent materials.
- Subjects
CHONGQING (China); SICHUAN Sheng (China); OXYGEN isotopes; CARBON isotopes; PETROPHYSICS; GAS reservoirs; CARBONATE rocks; ISOTOPIC analysis; FOSSILS; PHOSPHORUS cycle (Biogeochemistry); ORGANIC geochemistry
- Publication
Arabian Journal of Geosciences, 2023, Vol 16, Issue 8, p1
- ISSN
1866-7511
- Publication type
Article
- DOI
10.1007/s12517-023-11594-9