深部煤层CO_(2)注入煤岩力学响应特征及机理研究进展

Mechanical Response Characteristics and Mechanism of Coal-Rock with CO_(2) Injection in Deep Coal Seam: A Review

为揭示CO_(2)注入煤岩力学响应特征及机理,回顾了CO_(2)注入煤岩力学性质影响因素、CO_(2)注入对煤岩大分子-孔隙-裂隙结构改造作用和煤岩力学参数的统计模型、理论模型与智能预测模型.结果表明:CO_(2)注入煤岩力学性质受控于煤阶、CO_(2)压力、水分、围压和时间等因素,CO_(2)注入压力的增高、水的加入及时间的延长均会进一步降低煤岩力学性质,而围压对CO_(2)注入力学性能弱化具有一定改善作用.CO_(2)水溶液通过溶胀作用、萃取作用和塑化作用促使煤岩大分子结构重组,通过微晶结构改变、化学溶蚀和非均匀变形改造煤岩孔隙结构,通过化学溶蚀、膨胀应力和化学-应力耦合作用诱发煤岩结构损伤,均不同程度引起煤岩力学性能弱化.在CO_(2)注入煤岩力学参数预测模型中,类Langmuir模型、广延指数模型和修正的粘聚力模型具有明确的物理意义,而智能预测模型具有更高的预测精度,预测准确度可达99%以上.本次研究为科学评价CO_(2)-ECBM安全性和促进深部煤层CO_(2)高效注入奠定了理论基础.

To reveal the mechanical response characteristics and mechanisms of coal-rock with CO_(2) injection, the influencing factors of mechanical properties of coal-rock with CO_(2) injection, the transformation effect of CO_(2) on the macro molecular-porefracture structure of coal-rock and the statistical model, theoretical model and intelligence prediction model of mechanical parameters of coal-rock with CO_(2) injection were reviewed. Results show that mechanical properties of coal-rock with CO_(2) injection are controlled by the coal rank, the CO_(2) pressure, the moisture, the confining pressure and the time. The increase of CO_(2) injection pressure, the addition of water and the extension of time can further reduce the mechanical properties of coalrock with CO_(2) injection, while the confining pressure can ameliorate the weakening effect of mechanical property to a certain extent. The CO_(2) aqueous solution recombines the macro molecular structure of coal-rock by the swelling, extraction and plasticization effects, reforms the pore structure of coal-rock by the micro crystalline structure change, chemical corrosion and non-uniform deformation effects, damages the fracture structure by the chemical corrosion, swelling stress and chemical-stress coupling effects, which all weaken the mechanical properties of coal-rock in varying degrees. Among the prediction models of mechanical parameters of coal-rock with CO_(2) injection, the Langmuir-like model, the extended exponential model and the modified cohesion model have clear physical significance, while the intelligence prediction model has higher prediction accuracy,and the prediction accuracy can reach more than 99%. This study lays a theoretical foundation for scientifically evaluating the CO_(2)-ECBM safety and promoting the efficient injection of CO_(2) into deep coal seams.