Paleokarstic water tables and their control on reservoirs in Ordovician Yingshan Formation, Tazhong Area, Tarim Basin, NW China
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Paleokarstic water tables and their control on reservoirs in Ordovician Yingshan Formation, Tazhong Area, Tarim Basin, NW China |
| Haizhou QU,Maoyao LIU,Yunfeng ZHANG,Zhenyu WANG,Zhenghong ZHANG,Shiyin LI,Xingliang DENG |
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| Fig. 4. Identification of various stages of water tables in Yingshan Formation of Well G451. (a) Schematic diagram of karst profile of Yingshan Formation in Well G451, including delimiting of 3 stages of karst water tables and corresponding karst zones; (b) shows the characteristics above and below the first-stage water table in (a); there develop high-angle dissolved fractures in the vertical percolation zone above the first-stage water table, and cystic dissolved vug layers, and near horizontal dissolved fractures in the horizontal underflow zone below the first-stage water table; (c) shows the characteristics above and below the second-stage water table in (a); there develop high-angle dissolved fractures in the vertical percolation zone above the second-stage water table, but the horizontal underflow zone below the second-stage water table overlay reformed the first-stage karst fabrics, forming small dissolved caverns about 0.5 m in diameter; it can be seen that the horizontal dissolved fractures cut the first-stage high-angle dissolved fractures and there are large quantities of cystic dissolved vugs and near horizontal dissolved fractures occurring alternately; (d) shows the characteristics above and below the third-stage water table in (a); there are high-angle and oblique-crossing dissolved fractures in the vertical percolation zone above the third-stage water table, and the horizontal underflow zone below the third-stage water table overlay reformed the first-stage and second-stage karst fabrics, forming 4 caverns, including the one in this figure, with diameters of 0.7 m, 0.9 m, 1.0 m, and 1.1 m, respectively, and there develop cystic dissolved vugs. |
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