秦勇, 李恒乐, 张永民, 赵有志, 赵锦程, 邱爱慈. 基于地质–工程条件约束的可控冲击波煤层致裂行为数值分析[J]. 煤田地质与勘探, 2021, 49(1): 108-118,129. DOI: 10.3969/j.issn.1001-1986.2021.01.011
引用本文: 秦勇, 李恒乐, 张永民, 赵有志, 赵锦程, 邱爱慈. 基于地质–工程条件约束的可控冲击波煤层致裂行为数值分析[J]. 煤田地质与勘探, 2021, 49(1): 108-118,129. DOI: 10.3969/j.issn.1001-1986.2021.01.011
QIN Yong, LI Hengle, ZHANG Yongmin, ZHAO Youzhi, ZHAO Jincheng, QIU Aici. Numerical analysis on CSW fracturing behavior of coal seam under constraint of geological and engineering conditions[J]. COAL GEOLOGY & EXPLORATION, 2021, 49(1): 108-118,129. DOI: 10.3969/j.issn.1001-1986.2021.01.011
Citation: QIN Yong, LI Hengle, ZHANG Yongmin, ZHAO Youzhi, ZHAO Jincheng, QIU Aici. Numerical analysis on CSW fracturing behavior of coal seam under constraint of geological and engineering conditions[J]. COAL GEOLOGY & EXPLORATION, 2021, 49(1): 108-118,129. DOI: 10.3969/j.issn.1001-1986.2021.01.011

基于地质–工程条件约束的可控冲击波煤层致裂行为数值分析

Numerical analysis on CSW fracturing behavior of coal seam under constraint of geological and engineering conditions

  • 摘要: 可控冲击波(CSW)岩层致裂技术作为岩层改造领域的一项变革性技术,已在煤层改造等方面取得显著应用效果,并在煤炭安全开采领域开展应用探索。然而,受实验及现场监测条件限制,前期对地质-工程因素约束下的CWS岩层致裂基本规律理解不足,制约了对致裂机理的探索及现场作业参数的优化。鉴于此,在阐述CSW煤层改造及其面临的工程科学问题基础上,采用基于连续介质力学的离散元方法(CDEM)开展数值模拟,以进一步揭示地应力、煤岩力学性质、冲击波加载条件约束下的CSW煤层致裂行为及其基本规律。结果显示,CSW加载条件对致裂效果的影响存在最优范围,过度加载会导致近井地带煤体崩解,煤粉产出率增加,造成煤储层伤害;同时,煤体破碎导致波阻抗及冲击波衰减速度增大,限制有效改造半径扩展;地应力增大,破裂半径、破裂度存在临界值,水平主应力差对CSW冲击裂隙形态、扩展方位及缝网连通程度存在显著影响。研究揭示,CSW煤岩致裂效果对力学性质的响应存在选择性:弹性模量与破裂半径、破裂度之间存在拐点临界值;黏聚力增大,煤岩脆性变小,致裂效果变差;抗拉强度似乎对CSW致裂效果没有明显影响。研究成果可为CSW作业煤层优选及参数优化措施提供参考。

     

    Abstract: As a revolutionary technology for rock stratum reformation, the controllable shock wave(CSW) fracturing technology has achieved remarkable effect in coal seam reconstruction, and application exploration in the field of coal safety mining has been carried out. However, the previous understanding of the basic CWS fracturing rules under the constraints of geological engineering factors is insufficient due to the limitation of experimental and field monitoring conditions, which restricts the exploration of the fracturing mechanism and the optimization of the field operation parameters. In view of this, based on the description of CSW coal seam reformation and its engineering scientific problems, the CDEM method is used to carry out numerical simulation in order to further reveal the behavior and basic rules of CSW coal seam fracturing under the constraints of geo-stress, mechanical properties of coal and rock, and shock wave loading conditions. The results show that the influence of CSW loading conditions on the fracturing effect has an optimal range, and excessive loading will lead to coal disintegration near the wellbore, which increases the yield of pulverized coal and cause coal reservoir damage. At the same time, the wave impedance and shock wave attenuation increase due to coal fragmentation, which limits the expansion of fracturing radius. There are critical values of fracturing radius and fracturing degree with the increase of geo-stress and the horizontal principal stress difference significant effects on the morphology, expansion direction and connectivity of CSW-induced fractures. It is revealed that the fracturing effect has a selective response to the mechanical properties of coal:there is a critical value of inflection point in the plots of the elastic modulus to fracturing radius and fracturing degree; with the increase of cohesion, the brittleness of coal becomes smaller, and the fracturing effect becomes worse; the tensile strength seems to have no obvious effect on the CSW fracturing effect. Based on the above, there will be good references for the coal seam optimization and parameter optimization measures of CSW operation.

     

/

返回文章
返回