| Autor: |
Wang Yu-man, Li Xin-jing, Chen Bo, Han Jing, Zhang Jia-ming, Yuan Fei, Ma Jie, Dai Bing, Wang Hao, Jiang Shan |
| Předmět: |
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| Zdroj: |
Natural Gas Geoscience; Jan2018, Vol. 29 Issue 1, p42-42, 1p |
| Abstrakt: |
Based on the data from the outcrops and key exploratory wells.a basic analysis is provided to the distribution characteristics of the thickest bentonite layer of the Aeronian stage in Middle Upper Yangtze Region and its unique role in the geological evaluation of shale gas and the prediction of "sweet spot" layer. Three preliminary conclusions have been reached: ① The thickest bentonite layer of the Aeronian stage is widely and steadily distributed in the Middle-Upper Yangtze Region with a thickness of 5-40cm, whose e-lectric characteristics can be easily identified in most of the exploration areas.Gamma values of the bentonite layer are generally 188-235cps (or API).The gamma value peaks occur in southern Sichuan,eastern Sichuan and other primary shale gas exploration areas.On the contrary, in middle Sichuan, northeastern Sichuan and the north of Middle Yangtze Region,there is no gamma value peak or even the trough appears. ② The bentonite layer can be considered as the key marker layer of the mainly segmental partition and the regional comparison of Longmaxi Formation.In the field,it is an effective way to determine the upper bound ary of Rhuddanian, which can be found at the first appearance of the demirastrites and the first gamma curve trough. ③ The emergence of the thickest bentonite layer in the Aeronian stage has a profound influence on the formation and distribution of the high-quality shale of WufengLongmaxi Formation.Its appearance is an important symbol for foreland basin folding and sedimentary rate increasing.Meanwhile,it also represents a transition in Longmaxi Formation from organic-rich and silica-rich shale to clay-rich and calcium rich shale.Therefore, the organic rich and silica-rich shales were mainly formed before the occurrence of the benionile layer.and this control effect must be taken into account when predicting the spatial distribu lion of "sweet spot" layer in Wufeng-Longmaxi Formations.In most parts of the Middle-Upper Yangtze Region.the thickest bentonite layer in the Aeronian stage can be considered as the upper boundary of the high quality reservoir. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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