Key technologies and development direction of CBM exploration and development in coal mine area of fractured soft and low permeablity coal seams
Depending on the major national science and technology projects from the"12th Five-year Plan"to the"13th Five-year Plan",efforts are made to carry out technical research on the exploration and development of coalbed methane(gas)in coal mining ar-eas with fractured soft coal seams of low permeability.Through summarizing the results,the paper establishes the system involving the high-efficient coalbed methane(CBM)exploration and development mode,technique for determining reservoir parameters,pre-diction and simulation technique of extraction and production effect,as well as key technologies for extraction and production,which are applicable to CBM exploration in the fractured soft and low permeability coal seams.Further,it is suggested that the efficient de-velopment of CBM(gas)can be achieved by coal seam roof or floor strata fracturing and pressure-relief coal mining.An accurate test technology is developed for measuring coal seam sealed coring gas content in the surface well.Moreover,the paper proposes the pre-diction technology of gas content based on the temperature-pressure comprehensive adsorption model,and also the prediction and simulation technology of staged fracturing in roof horizontal well and gas extraction in mining well.These achievements can provide an effective means for accurately pre-evaluating the gas-bearing capacity and development potential of fractured soft coal seams with low permeability.Additionally,the technological process of staged fracturing in horizontal well and long borehole in underground coal mine has also been established.Based on above results,field engineering tests have been carried out in several coal mines in An-hui,Shanxi and Shaanxi Provinces,achieving a great breakthrough in surface well development and underground extraction of CBM(gas)from fractured soft and low permeability coal seams.Based on the characteristics of CBM reservoirs in fractured soft and low permeability coal seams and the actual demands from coal mining areas,it is proposed that in the future,more attention should be paid to the fields including deep well pressure-maintaining sealed coring technology,precise control technology of drilling trajectory,intelligent fracturing and drainage technology,as well as subsection hydraulic fracturing technology in underground coal mines.
coal mining areafractured soft and low permeability coal seamcoalbed methaneexploration and developmentkey technologiesdevelopment trend
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