1. Eogenetic karst and its control on reservoirs in the Ordovician Majiagou Formation, eastern Sulige gas field, Ordos Basin, NW China
- Author
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Mengying Yang, Xiucheng Tan, Min Feng, Wancai Nie, Kang Xie, Shoukang Zhong, Zhanfeng Qiao, Wang Baobao, and Wei Zeng
- Subjects
Dolomite ,0211 other engineering and technologies ,Geochemistry ,Energy Engineering and Power Technology ,02 engineering and technology ,Structural basin ,010502 geochemistry & geophysics ,reservoir characteristics ,01 natural sciences ,Geochemistry and Petrology ,021108 energy ,lcsh:Petroleum refining. Petroleum products ,Dissolution ,0105 earth and related environmental sciences ,geography ,geography.geographical_feature_category ,Ordovician ,eogenetic karst ,Geology ,Geotechnical Engineering and Engineering Geology ,Karst ,Petroleum reservoir ,Natural gas field ,dolomite ,lcsh:TP690-692.5 ,Economic Geology ,Majiagou Formation ,porous reservoir - Abstract
To further ascertain the origin of the Ordovician Majiagou Formation reservoirs in the Ordos Basin, the M54-M51 sub-members of the Ordovician Majiagou Formation in the eastern Sulige gasfield of Ordos Basin were taken as examples to analyze the vertical development characteristics of eogenetic karst and to discover the dissolution mechanism and its control on reservoirs through observation of a large number of cores and thin sections. According to detailed analysis of petrologic characteristics, the reservoir rock types include micritic dolomite, grain dolomite and microbialite which have mainly moldic pore, intergranular (dissolved) pore, and (dissolved) residual framework pore as main reservoir space respectively. The study area developed upward-shallowing sequences, with an exposure surface at the top of a single upward-shallowing sequence. The karst systems under the exposure surface had typical exposure characteristics of early dissolution and filling, indicating these reservoirs were related to the facies-controlled eogenetic karstification. With the increase of karstification intensity, the reservoirs became worse in physical properties.
- Published
- 2020