气相聚能压裂煤层的三维效应研究
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摘要
液体二氧化碳相变气爆是一种点式气相聚能压裂技术,其对煤体致裂的三维效应是探究增透效果的重要判据。基于自主设计搭建的物理实验平台,实验研究得出了气爆压降的时空演化规律,气爆气体压力峰值与爆破口距离的空间关系呈二次抛物线形式,拟合关系式为y=0.04x~2-5.86x+227.6;气爆气体压力上升时间与爆破口距离的时间关系呈幂函数形式,拟合关系式为y=8.78x~(0.143 7)。数值模拟分析得出气相聚能压裂煤体的塑性区呈现以爆破孔轴向为长轴的近似椭圆体发育的分布规律;当气爆峰值压力为160 MPa和200 MPa时,2种工况对应的最大有效致裂半径分别为0.50 m和0.60 m,最大致裂半径增加约20%;致裂体积分别为0.50 m~3和0.95 m~3,致裂体积增加近1倍。
Liquid carbon dioxide phase change gas explosion is a kind of point type gas gathering energy fracturing technology,and its three-dimensional effect on coal body cracking is an important criterion to explore the permeability improvement effect.Based on the self-designed and built physical experimental platform,the spatial-temporal evolution law of gas explosion pressure drop was obtained through experimental research.The spatial relationship between gas explosion pressure peak and blasting mouth distance was a quadratic parabola,and the fitting relationship was y=0.04x~2-5.86x+227.6.The time relation between gas pressure rise time and blast hole distance is a power function form,and the fitting relation is y=8.78x~(0.143 7).The numerical simulation results show that the plastic area of the gas energy gathering fracturing coal presents a similar ellipsoid development pattern with the axial direction of the blasting hole as the long axis.When the peak pressure of gas explosion is 160 MPa and 200 MPa,the maximum effective crack radius corresponding to the two working conditions is 0.50 m and 0.60 m respectively,and the maximum approximate crack radius increases by about 20%.The cracking volume was 0.50 m~3and 0.95 m~3,respectively.
Liquid carbon dioxide phase change gas explosion is a kind of point type gas gathering energy fracturing technology,and its three-dimensional effect on coal body cracking is an important criterion to explore the permeability improvement effect.Based on the self-designed and built physical experimental platform,the spatial-temporal evolution law of gas explosion pressure drop was obtained through experimental research.The spatial relationship between gas explosion pressure peak and blasting mouth distance was a quadratic parabola,and the fitting relationship was y=0.04x~2-5.86x+227.6.The time relation between gas pressure rise time and blast hole distance is a power function form,and the fitting relation is y=8.78x~(0.143 7).The numerical simulation results show that the plastic area of the gas energy gathering fracturing coal presents a similar ellipsoid development pattern with the axial direction of the blasting hole as the long axis.When the peak pressure of gas explosion is 160 MPa and 200 MPa,the maximum effective crack radius corresponding to the two working conditions is 0.50 m and 0.60 m respectively,and the maximum approximate crack radius increases by about 20%.The cracking volume was 0.50 m~3and 0.95 m~3,respectively.
引文
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[3]Erzi Tang,Chong Peng.A macro-and microeconomic analysis of coal production in China[J].Resources Policy,2017,51(4):234-242.
[4]Dong-Liang Zhong,Wen-Chun Wang,et al.Investigation on methane recovery from low-concentrationcoalminegasby tetra-n-butyl ammonium chloride semiclathrate hydrate formation[J].Applied Energy,2018,227(10):686-693.
[5]Yunxing Cao,Junsheng Zhang,Hong Zhai,et al.CO2gas fracturing:A novel reservoir stimulation technology in low permeability gassy coal seams[J].Fuel,2017,203(1):197-207.
[6]张家行,张兴华,李豪君.CO2致裂技术机理及其在底鼓治理中的应用[J].煤矿安全,2017,48(1):70-73.
[7]汪开旺.高压空气爆破煤层致裂增透工艺研究[J].煤炭科学技术,2018,46(2):193-197.
[8]李守国,贾宝山,聂荣山,等.裂纹闭合对高压空气爆破冲击煤体瓦斯抽采效果影响[J].煤炭学报,2017,42(8):2026-2030.
[9]雷云,刘建军,张哨楠.CO2相变致裂本煤层增透技术研究[J].工程地质学报,2017,25(1):215-221.
[10]雷云.低渗透高瓦斯煤层二氧化碳相变致裂增透理论及实验研究[D].成都:西南石油大学,2018.