Analysis On Formation Conditions And Process Of Coal Bed Methane Reservoir

Depending on the history and status of coal bed methane exploration, developing and studying in China and foreign countries, the author has researched systematically coal seam distribution, coal gas ingredients, gas content, physical characteristics of reservoir, resorption characteristics, reservoir pressure, closure conditions in the course of developing coal bed methane of Qinshui Basin. The zones of coal bed methane reservoir can be divided six kinds. According to the main clues of hydrodynamic conditions together with structure characteristics and boundary types of coal bed methane reservoir, coal bed methane reservoir can divided two types, namely hydrodynamic closure and self closure. On the base of coal rank kinds coal bed methane can also be made off high rank, medium low rank and low rank..Depending upon the characteristics of coal seam geochemistry the author puts forward the classification method of coal bed methane formation. By citing resorption potential theory it can be evaluated the history of coal bed methane congregation quasi-quantitatively. As a result, it can be disclosed the mechanism of coal bed methane distribution, displacement and fractionation. And he has built a new approach to forecast the rich areas of coal bed methane. In the mean time it can be found that the relation between stimulating coal gas by dioxide nitrogen and injecting pressure and reservoir pressure is closed. On the other hand, he has provided new theoretic bases for improving coal bed methane recovery.By citing Hery law and comparability principle in studying solubility of coal gas in water the author has evaluated quantitatively different coal gas ingredients and different carbon isotopes' coal gas dissolving into water, talked the mechanism of dissolving and separating of coal gas, pointed that the displacement ways of coal gas lie in not only gas distribution to seepage by dissociation but also dissolving displacement. And the author systematically has analyzed the differences of high, medium and low rank coal gas reservoirs formation from formation conditions and process on the basis of analysis on the homeland and broad coal basin, selecting the south of Qinshui basin, Piceance basin, Fuxin Basin' Wangying-Liujia blocks and Power basin's different ranks coal seam. The main control factors of coal gas reservoir formation are put forwarded in the dissertation. The model of reservoir formation of coal gas enrichment is built for high, medium and low rank types by quoting the concept of key moment of reservoir formation and evolvement. It can be utilized in evaluating and selecting the blocks for coal bed methane exploration.