废弃矿井煤层气资源丰富，抽采废弃矿井煤层气，已成为煤矿区煤层气的重要资源之一。基于山西晋城矿区废弃矿井煤层气抽采实际，系统介绍了废弃矿井采空区煤层气赋存特征及其地面抽采技术的研究进展，分析了废弃矿井采空区煤层气地面抽采研究现状和存在的问题，提出了目前我国废弃矿井采空区煤层气地面抽采研究面临的关键科学问题和研究内容。研究结果表明，煤炭开采形成的冒落-断裂带，为采空区煤层气赋存提供了储集空间。废弃矿井采空区煤层气主要来源于煤柱及残留煤层、临近未采煤层和围岩中的游离气和吸附气，基于体积法对废弃矿井采空区吸附气和游离气资源分别进行计算和评价。为有效解决采空区上部含水层涌水对钻井井身稳定性及抽采效果的影响，将采空区煤层气抽采井身结构由二开优化为三开结构，优先采用压缩空气潜孔锤钻井技术，用氮气取代空气作为循环介质安全揭露含气断裂带的井工艺技术；根据晋城矿区废弃矿井采空区煤层气井抽采过程中压力和日产气量的变化特征，将采空区煤层气井抽采划分为自由放喷、气量快速下降、稳压产气和定量产气4个阶段，并提出了适用于废弃矿井采空区煤层气抽采的“四段制”抽采控制方法；最后，指出了目前面临“废弃矿井煤层气赋存规律及其控制机理和废弃矿井煤层气抽采条件评价及抽采参数优化方法”2个关键科学问题和“废弃矿井煤层气赋存规律及其控制机理、废弃矿井煤层气资源评价模型与方法和废弃矿井采空区煤层气抽采技术”等研究内容。

There are abundant coalbed methane (CBM) resources in abandoned coal mines, and the extraction of CBM from abandoned coal mines has become one of the important CBM resources in coal mining areas.Based on the practice of CBM extraction in abandoned mines in Jincheng mining area of Shanxi Province, this paper systematically introduced the occurrence characteristics of CBM resources in abandoned mine gob and its surface drainage technology, and analyzed the research status and existing problems of CBM surface drainage in abandoned mine gob. The current key scientific problems and research contents of surface drainage of CBM in abandoned mine gob in China have been put forward.The research shows that the caving-fracture zone formed by coal mining provides a reservoir space for the occurrence of CBM in the gob. The CBM in the abandoned mine goaf mainly contains adsorbed gas and free gas which comes from the coal pillars, residual coal seams, adjacent unmined coal seams and surrounding rocks. Based on the volumetric method, the calculation methods of adsorbed gas and free gas resources are used to calculate and evaluate the CBM resources of abandoned coal mine. In order to effectively solve the influence of water inrush from the upper aquifer in the gob on the stability of the drilling well and the drainage effect, the wellbore structure of the CBM extraction well in the gob is optimized from secondspud to third spud structure, and compressed air down-the-hole (DTH) hammerdrilling technology is preferentially used, and the nitrogen is used instead of air as the circulating medium to safely expose the well technology of the gas-bearing fracture zone.According to the variation characteristics of pressure and daily gas production in the extraction process of CBM in gob of abandoned mine in Jincheng mining area, the CBM extraction in gob is divided into four stages: free ejection, rapid gas decline, stable gas production and quantitative gas production, and a “four-stage” extraction control method suitable for coalbed methane extraction in abandoned mine gobs is proposed. Finally, it points out the two key scientific issues currently facing “the occurrence law of coalbed methane in abandoned mines and its control mechanism and the evaluation of coalbed methane extraction conditions in abandoned mines and the optimization of extraction parameters” and ”the occurrence law of coalbed methane in abandoned mines and its research content such as control mechanism, CBM resource evaluation models and methods in abandoned mines, and CBM extraction technology in abandoned mine gobs.”

0 引言

1 废弃矿井采空区煤层气赋存特征

   1.1 采空区煤层气赋存状态

   1.2 采空区煤层气成分

   1.3 采空区煤层气资源评价

2 废弃矿井采空区煤层气地面抽采国内外研究现状

3 晋城矿区废弃矿井煤层气地面抽采研究

   3.1 研究区抽采概况

   3.2 废弃矿井采空区煤层气抽采工艺与技术

4 关键科学问题与研究内容

   4.1 关键科学问题

   4.2 研究内容

5 结语