1
水力压裂-深孔预裂爆破复合增透技术研究
高鑫浩
1,2,3
,王明玉
4,5
(1. 煤炭科学研究总院,北京 100013;2
.
煤科集团沈阳研究院有限公司,辽宁 沈阳 110016;3. 煤矿
安全技术国家重点实验室,辽宁 抚顺 113122;4. 辽宁工程技术大学 安全科学与工程学院,辽宁 阜新
123000;5. 矿山热动力灾害与防治教育部重点实验室,辽宁 葫芦岛 125105)
基金项目:国家重点研发计划
2107YFC0805200
作者简介:高鑫浩(1994—),男,汉族,辽宁鞍山人,硕士研究生。Tel:13941214667,E-mail:gaoxinhaoo@163.com
摘 要:为了增加低渗透高瓦斯煤层的透气性,提高瓦斯的利用率和抽采效率,提出了水力压裂-深孔预裂爆破复合增透技术。
本文分析了水力压裂-深孔预裂爆破复合增透的爆破致裂机理,建立了在爆轰气体作用下的裂纹应力强度因子方程和裂纹二
次扩展半径方程。利用 RFPA
2D
-Flow 和 ANSYS/LS-DYNA 有限元分析模拟软件分别对水力压裂后孔壁周围煤岩体从微小裂
隙的产生、逐渐延伸与裂隙扩展规律以及在深孔预裂爆破前制造不同长度的预裂缝对爆破致裂后瓦斯抽采增透效果的影响情
况分别进行了数值模拟。同时在阳泉五矿 8410 工作面开展了现场工业性试验,以此验证煤矿井下进行水力压裂-深孔预裂爆
破复合增透技术后的瓦斯抽采增透效果。结果表明:使用水力压裂-深孔预裂爆破复合增透技术后煤层的透气性与常规的深
孔预裂爆破相比有显著的提高,致裂孔的初始瓦斯涌出量是普通爆破孔的 3.18 倍,瓦斯含量的衰减强度降低了 77.3%。深
孔预裂爆破的有效影响半径随着爆破孔内预裂缝长度的增加而提高,而且二者呈线性关系。本文中采用复合爆破后的致裂有
效半径可达到 6.98m,与数值模拟结果得到的致裂有效半径 6.763m 相符。同时数值模拟与现场工业性试验的结果均证明:
本文提出的水力压裂-深孔预裂爆破复合增透技术,能够有效的增加煤岩层的透气性,提高瓦斯的抽采效率,为其他低渗透
高瓦斯煤层的瓦斯抽采增透技术提供了参考价值。
关键词:水力压裂;复合增透;数值模拟;瓦斯治理
中图分类号:X932 文献标识码:A
Study on Hydraulic Fracturing-Deep Hole Pre-splitting Blasting
Composite Permeability Enhancement Technology
GAO Xinhao
1,2,3
,WANG Mingyu
4,5
(1. Mine Safety Branch,Beijing 100013,China; 2. Coal Research Institute, Shenyang Research Institute, Ltd., Liaoning Shenyang
110016, China; 3. Key Laboratory of Mine Thermal Power Disaster and Prevention, Ministry of Education, Fushun 113112,China
;
4. College of Safety Science and Engineering, Liaoning Technical University, Fuxin 123000,China;5. Key Laboratory of mine
power disaster and prevention of Ministry of education, Liaoning Huludao 125105,China)
Abstract: To increase the permeability of low permeability and high gas coal seam and improve the gas utilization rate and extraction
efficiency, a hydraulic fracturing-deep hole presplitting blasting composite anti-reflection technology was proposed. The mechanism
of blasting cracking in hydraulic fracturing-deep-hole pre-split blasting was analyzed, and the crack stress intensity factor equation
and the crack secondary radius equation under the action of detonation gas were established. Using RFPA
2D
-Flow and
ANSYS/LS-DYNA finite element analysis and simulation software to produce different lengths of the coal-rock mass around the
pore wall after hydraulic fracturing from the micro-fracture, the gradual extension and the crack propagation law, and the different
lengths before the deep-hole pre-split blasting. The effects of pre-cracks on the effect of gas drainage after blasting were numerically
simulated. At the same time, an on-site industrial test was carried out on the 8410 working face of Yangquan Minmetals to verify the
gas drainage effect of the coal mine underground under the hydraulic fracturing-deep hole pre-cracking composite anti-reflection
technology. The results showed that the permeability of the coal seam was significantly improved compared with the conventional
deep-hole pre-splitting blasting after the hydraulic fracturing-deep-hole pre-split blasting composite anti-reflection technology. The
initial gas emission of the cracked holes was the common blasting hole 3.18 times, the attenuation intensity of gas content was
reduced by 77.3%. The effective influence radius of deep-hole pre-splitting blasting increases with the increase of the pre-crack
length in the blasthole, and the relationship between them was linear. The effective radius of cracking after composite blasting could
reach 6.98m, which was obtained with numerical simulation results. The effective radius of cracking was 6.763m. At the same time,
the results of numerical simulation and field industrial test proved that the hydraulic fracturing-deep hole pre-splitting blasting
composite permeability enhancement technology proposed in this paper could effectively increase the permeability of coal seam,
improved the gas extraction efficiency, and provided reference value for other low permeability and high gas seam gas extraction and
permeability enhancement technology.
Key words:Hydraulic fracturing;Compound permeability enhancement;Numerical simulation;Gas control