关键词: 煤矿区, 碎软低渗煤层, 煤层气, 勘探开发, 关键技术, 发展方向

Abstract: 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 areas 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, prediction 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 development 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 prediction 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 Anhui, 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.

Key words: coal mining area, fractured soft and low permeability coal seam, coalbed methane, exploration and development, key technologies, development trend