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- Title
鄂西地区上奥陶统五峰组观音桥段成因 及其页岩气地质意义.
- Authors
沈均均; 杨丽亚; 王玉满; 计玉冰; 李 辉; 王鹏万; 蔡全升; 孟江辉
- Abstract
There has always debated whether the Guanyinqiao interval of the Upper Ordovician Wufeng Formation is of deep or shallow water origin. Based on data such as core, outcrop, rock, mineral tests, organic geochemistry, and elemental analysis, this study analyzed the basic geological characteristics and sedimentary paleo-environment of the Guanyinqiao interval, and compared them with those of the upper and lower surrounding rocks to discuss the genetic model and geological significance of shale gas. The results show that the global sea level dropped sharply during the Hirnantian glaciation. The western Hubei region has the characteristics of low terrigenous input, active upwelling currents, moderate retention and high marine productivity. The redox conditions of water column in the western Hubei are obviously different in different regions, which is controlled by sea level changes and paleo-geomorphology, and further affects the lithology of the Guanyinqiao interval. The depositional environment of the bottom water is mainly reductive environment in the depression, and its redox state has a relatively weak relationship with the declining sea level. The preservation conditions of organic matter and plankton are better. The lithology of the Guanyinqiao interval was mainly organic rich deep-water siliceous shale, which is basically consistent with the lithology of the upper and lower surrounding rocks. Volume fracturing can simultaneously transform two sets of gasrich shale through the Guanyinqiao interval, which is a favorable area for exploration and development. In the uplift, the drop of sea level leads to the obvious shallower water, and the bottom water is dominated by oxygen-rich environment, with poor preservation condition. The lithology of the Guanyinqiao interval was mainly composed of the shallow-water shell limestone and argillaceous limestone deposits with poor organic matter, which produces obvious partition to the upper and lower surrounding rocks. It is difficult to cross the Guanyinqiao interval by volume fracturing in the uplift, and the production zone reconstruction effect is poor, so the uplift area is a secondary favorable area.
- Subjects
HUBEI Sheng (China); GEOLOGICAL modeling; SEA level; BOTTOM water (Oceanography); MARINE productivity; WATER depth; ANOXIC zones; SAPROPEL
- Publication
Journal of China University of Petroleum, 2023, Vol 47, Issue 2, p13
- ISSN
1673-5005
- Publication type
Article
- DOI
10.3969/j.issn.1673-5005.2023.02.002