A theoretical basis for the optimization of carbon dioxide injection parameters and the development of the drainage system can be provided by identifying the permeability change characteristic of coal and rock after i...A theoretical basis for the optimization of carbon dioxide injection parameters and the development of the drainage system can be provided by identifying the permeability change characteristic of coal and rock after injection of carbon dioxide into the coal seam. Sihe, Yuwu, and Changcun mines were used as research sites. Scanning electron microscopy and permeability instruments were used to measure coal properties such as permeability and surface structure of the coal samples at different pH values of carbon dioxide solution and over different timescales. The results show that the reaction between minerals in coal and carbonate solution exhibit positive and negative aspects of permeability-the dissolution reaction between carbonate minerals in coal and acid solution improves the conductivity of coal whilst, on the other hand, the clay minerals in the coal （mainly including montmorillonite, illite and kaolinite） exhibit expansion as a result of ion exchange with the H~ in acid solution, which has a negative effect on the per- meability of the coal. The permeability of coal samples increased at first and then decreased with immer- sion time, and when the soaking time is 2-3 months the permeability of the coal reached a maximum. In general, for coals with permeabilities less than 0.2 mD or greater than 2 roD, the effect on the permeabil- ity is low： when the permeability of the coal is in the range 0.2-2 mD, the effect on the permeability is highest. Research into permeability change characteristics can provide a theoretical basis for carbon diox- ide injection under different reservoir permeability conditions and subsequent drainage.展开更多
基金the Major Projects of National Science and Technology Project‘‘Development of Coal-Bed Gas Dynamic Evaluation Model and Software System’’support under contract number 2011ZX05034-005 and 2011ZX05042-003Henan Polytechnic University Outstanding Youth Fund under contract number J2013-03
文摘A theoretical basis for the optimization of carbon dioxide injection parameters and the development of the drainage system can be provided by identifying the permeability change characteristic of coal and rock after injection of carbon dioxide into the coal seam. Sihe, Yuwu, and Changcun mines were used as research sites. Scanning electron microscopy and permeability instruments were used to measure coal properties such as permeability and surface structure of the coal samples at different pH values of carbon dioxide solution and over different timescales. The results show that the reaction between minerals in coal and carbonate solution exhibit positive and negative aspects of permeability-the dissolution reaction between carbonate minerals in coal and acid solution improves the conductivity of coal whilst, on the other hand, the clay minerals in the coal （mainly including montmorillonite, illite and kaolinite） exhibit expansion as a result of ion exchange with the H~ in acid solution, which has a negative effect on the per- meability of the coal. The permeability of coal samples increased at first and then decreased with immer- sion time, and when the soaking time is 2-3 months the permeability of the coal reached a maximum. In general, for coals with permeabilities less than 0.2 mD or greater than 2 roD, the effect on the permeabil- ity is low： when the permeability of the coal is in the range 0.2-2 mD, the effect on the permeability is highest. Research into permeability change characteristics can provide a theoretical basis for carbon diox- ide injection under different reservoir permeability conditions and subsequent drainage.
