Geological Evaluation Theory and Technology Progress of Coal Reservoir Dynamics During Coalbed Methane Drainage

Taking Qinshui and Ordos basins as the research objects, four theoretical knowledges were sugessted such as the geological control modes of CBM hig h- production wellblock, the dynamic and mathematical model of coal reservoir properties, the multiple superposed CBM systems ( MS- CBMS) and the numerical descri ption of CBM drainage and desorption phases. Four evaluation technologies were developed including the nuclear magnetic resonance characterization of coalbed wate r and pore, the comprehensive geological evaluation of favorable CBM production- building region, the geological design of progressive CBM drainage for the MS- CBM S, and the geological evaluation of coal reservoir development dynamic. Three sets of the equipments were developed for the physical simulation of the CBM drainage under the multiple coalbeds and fields, the detection of the fluid parameters in vertical CBM wells and the detection of the CBM content with natural ultra- low frequency electromagnetic wave. A geological service technology system framework of the CBM drainage suitable to the geological conditions of the basins had been initially set u p, so as to provide a basis for meeting the national demands of large- scale CBM development.