超长工作面CO2相变致裂分区增透高效抽采技术试验研究

Experimental study on partitioned permeability enhancement high-efficiency extraction technology of CO2 phase change fracturing in ultra-long working face

针对超长工作面抽采时间不均衡导致抽采达标时间长的问题,提出了工作面分区增透高效抽采技术,运用分组试验和理论分析的方法,研究了不同布孔工艺参数条件下CO2相变致裂对低透煤层瓦斯抽采的增透作用规律,并在试验工作面进行了工业应用。研究结果表明:CO2相变致裂技术对低透煤层增透促抽效果良好,与未致裂抽采相比,采用间距20,10,5 m致裂孔致裂条件下进行抽采时煤层透气性系数分别提高1. 8,2. 6,5. 8倍,平均抽采体积分数分别提高1. 9,3. 5,4. 2倍,平均抽采纯量分别提高2. 4,4. 2,6. 2倍。试验工作面应用分区增透高效抽采技术后,整个工作面形成后仅需抽采87 d即可达标进行回采,显著缩短了抽采周期,对高瓦斯低透煤层缓解采掘接替紧张及提高瓦斯抽采效率具有重要借鉴意义。

Aiming at the problem that the uneven extraction time of ultra-long working face leads to a long time to reach the standard of extraction,a technology of partitioned permeability enhancement high-efficiency extraction for the working face was put forward.By means of grouping experiment and theoretical analysis,the laws of permeability enhancement for the gas extraction in low permeability coal seam by CO2 phase change fracturing under different hole distribution parameters were studied,and the industrial application was carried out in the experimental working face.The results showed that CO2 phase change fracturing technology had good effect on permeability enhancement and extraction promotion in the low permeability coal seam.Compared with the non-fractured extraction,when the spacing of fracturing holes was 20,10 and 5 m for the fractured extraction,the permeability coefficient of coal seam increased by 1.8,2.6 and 5.8 times,the average extraction volume fraction increased by 1.9,3.5 and 4.2 times,and the average extraction pure quantity increased by 2.4,4.2 and 6.2 times respectively.After the application of partitioned permeability enhancement high-efficiency extraction technology in the experimental working face,the whole working face could reach the standard for mining with only 87 days of extraction after it was formed,which significantly shortened the extraction period.It has important reference significance for alleviating the tension of mining replacement and improving the efficiency of gas extraction in the high gas and low permeability coal seams.