Geochemical Characteristics and Formation of Dolostones from the Changxing Formation at Puguang Gas Field in
详细信息
- 责任者：Li Zhiming (Wuxi Research Institute of Petroleum Geology ; Exploration and Production Research Institute ; SINOPEC ; Wuxi 214151 ; China) ; Xu Ershe
- 刊名：Geochimica
- 出版年：2010
- 卷期：39(4)
- 关键词：白云岩 ; dolostone ; 四川 ; Sichuan Province
- 页码：p.371-380
- 图表：3 illus., 4 tables, 32 refs.
- 分类号：0803
- issnNo：ISSN0379-1726
- isbnNo：CN44-1398/P
摘要
The study on mineral and geochemical characteristics of dolostones from Changxing Formation at Puguang gas field in Sichuan Basin shows that the degrees of crystallization and order are generally increased from southeast to northwest. For dolostone samples from well Puguang 8 to Puguang 5 and Puguang 6, Fe, Mn, Al, K, Na and Sr concentrations and Mg2 + /Ca2 + decrease gradually, δ18OPDB also decreases, whereas δ13CPDB increases slightly, showing a negative relationship, which suggest that the dolomitization was not related to mixed water. Meanwhile, 87Sr / 86Sr of crystalline dolostones of well Puguang 6 are systematically higher than that of paleo-seawater of the Late Permian, suggesting the dolomitization fluid was not derived from Changxing stage paleo-seawater. It is concluded that the micritic dolostones and dolomicrites of Changxing Formation are mainly penecontemporaneous dolostones formed from rapid metasomatic diagenesis by hypersaline water. The crystallized dolostones and cataclastic dolostones formed through buried diagenesis and the dolomitization fluid were hypersaline formation water derived from Permian seawater, and thus can be excellent gas reservoirs.