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

摘要： 依托2011—2020年国家科技重大专项,开展了碎软低渗煤层煤矿区煤层气勘探开发技术研究,梳理形成了适合于碎软低渗煤层的煤层气高效开发方式、储层参数确定技术、抽采效果预测模拟技术、抽采关键技术的成果体系,提出了压裂煤层顶底板岩层、煤炭采动卸压两种途径能实现碎软低渗煤层煤层气高效开发的认识。研发了地面井煤层密闭取心-气含量精确测试技术,提出了基于温度—压力综合吸附模型的气含量预测技术、顶板水平井分段压裂与采动井煤层气抽采的预测模拟技术。这些成果为准确预评价碎软低渗煤层含气性和开发潜力提供了有效手段。建立了地面顶板水平井分段压裂与煤矿井下长钻孔分段压裂的技术工艺流程。基于取得的研究成果,在安徽省、山西省、陕西省等地区的多个煤矿进行了现场工程试验,获得了碎软低渗煤层煤层气地面开发和井下抽采的重大突破。综合碎软低渗煤层煤层气储层特性及煤矿区实际需求,提出在煤矿区今后应重点关注深井保压密闭取心技术、钻孔轨迹精准控制技术、智能压裂与排采技术、煤矿井上下联合分段压裂技术等领域。

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