超临界二氧化碳多脉冲气爆低渗透煤层抽采瓦斯增产机理研究

For the low gas production problem because of generally low permeability coal seams with high methane in China and compression effect due to increasing stress around the coal bed gas drainage hole when drilled as well as coal and rock debris carried by gas flow deposition and obstruction, we combine experiments, theory and numerical simulation to research on production increasing mechanism by multi-pulse super critical CO2 bursting in the hole enhanced methane extraction. We improve the monopulse unloading device and develop the seepage and multi-pulse burst function integration experiment system together with existing Thermo-Fluid-Mechanical coupling permeameter; research on the permeability increasing mechanism of coal seams fracture,which is influenced by stress waves and bursted CO2 during super critical CO2 bursting;research on the adsorption-desorption and seepage change law of CH4/CO2 in coal seams because coal bed failure and fracture and its damage evolution and stress waves when bursted CO2 shocked. Reveal the production increasing mechanism of super critical CO2 bursting in low-permeability coal seams. Establish the super critical CO2 burst increase coal seam permeability mechanical model and methane migration coupling model in the coal seam with fracture random distribution; Research on the algorithm and program integrated the rupture damage geometrical characteristic and heterogeneous physical property parameters after CO2 bursting into abaqus to realize the prediction of permeability increasing effect in low permeability coal seam and methane occurrence and migration rule after permeability increasing; The research results have important theoretical significance and application value for safety in production and methane efficient utilization in coal seams with high gas.

为解决我国高瓦斯煤层普遍渗透性低和瓦斯抽采孔孔周应力升高形成的压密效应以及抽采中瓦斯流体携带煤岩碎屑在孔周沉积阻塞导致产气率低的难题，采用实验、理论和数值模拟相结合方法，开展对瓦斯抽采孔利用超临界CO2实施多脉冲气爆强化抽采瓦斯增产机理研究：改进单脉冲卸压装置并与现有热流力耦合渗透仪形成渗流与多脉冲气爆功能一体化的实验系统；研究超临界CO2气爆产生的应力波和爆生气体对煤体破裂增透规律；研究煤体冲击破坏断裂及损伤演化以及应力波对煤层CH4/CO2吸附解吸和渗流的影响规律；揭示超临界CO2气爆低渗透煤层增产机理和规律；建立超临界CO2气爆增透力学模型和裂隙随机分布煤层瓦斯运移耦合模型；研究将气爆后煤层破坏损伤几何特征和物性参数非均质信息与ABAQUS集成的算法和程序，实现对低渗透煤层增透效果和增透后瓦斯赋存运移规律预测，研究成果对高瓦斯煤矿安全生产和瓦斯高效利用具有重要的理论意义和应用价值。

为解决我国低渗透高瓦斯煤层产气率低的难题，本项目在四年执行期内，严格按照项目计划任务书规定的内容开展工作：自主研制多脉冲气爆功能实验系统；研究超临界二氧化碳气爆过程中应力波和爆生气体对煤体破裂增透机理；研究煤体冲击破坏断裂及损伤演化对煤层渗流的影响规律；揭示超临界二氧化碳气爆低渗透煤层增产机理和规律,建立气爆增透力学模型；研究低渗透煤层增透效果和增透后瓦斯赋存运移规律数值预测方法。. 项目的主要研究成果：自制完成了具有热流力耦合渗流测试功能与超临界CO2可控多脉冲气爆一体化的实验系统;得到了超临界CO2可控多脉冲气爆低渗透性煤层增透机理和气爆增透后煤层瓦斯的吸附、解吸和渗流规律以及气爆应力波对煤层瓦斯吸附、解吸的影响规律;建立了超临界CO2气爆增透力学模型和裂隙随机分布的双重介质气爆增透后煤层甲烷运移耦合模型; 实现了对低渗透煤层增透效果和增透后瓦斯赋存运移规律预测。. 项目执行期间，在国内外核心学术期刊发表论文45篇，其中SCI、EI收录17篇，出版专著1部，授权专利8项，获得省优秀博士论文1篇，获中国煤炭学会青年科学技术优秀博士论文提名奖1篇，研究成果实现技术转化，研制井下煤仓超临界解堵设备14套，应用7个煤矿，产生效益500余万元。国内外学术交流50人次，项目负责人做特邀报告4次；培养团队年青教师5名。培养毕业研究生13人，其中博士4人（2人获得优秀博士论文），硕士9人。研究成果为安全高效的低渗透煤层超临界二氧化碳多脉冲气爆增透新技术奠定技术基础，具有重要的理论意义和应用价值。