深部低渗透高瓦斯煤层瓦斯抽采基础研究

The project combined measures such as multi-scale and multi-field coupling experiment, field testing and monitoring, theory analysis of multi-field coupling, and numerical simulation. The project studied the basic theory and scientific problem of deep low-permeability high gas seam in the process of coal seam mining and explored the high efficient gas drainage mechanism of deep low-permeability and high gas pressure coal seam. Based on theory and experiment study on adsorption and desorption mechanism of low-permeability coal seam in multi-field coupling condition, the seepage mechanism of low-permeability coal seam in deep and multi-field coupling condition was revealed and the permeability theory model of deep low-permeability coal-rock mass was established. The experimental research of macroscopic and microscopic fissure field’s evaluation law of coal-rock was studied under different scales, the macroscopic and microscopic fissures of coal-rock were observed, and the damage-fracture and gas seepage theory model of coal-rock with the influence of multi-field was built. Furthermore, the failure of low-permeability coal-rock caused by water pressure and deep hole explosion increased permeation mechanism were studied with the help of Large Mining Simulation Experiment System of Coal Containing Gas with Multi-field Coupling..Based on the result of damage and fracture seepage model and numerical simulation, the breaking and gas flowing as well as enrichment law in pressure relieve area of coal-rock mass were studied, the efficient measures which can be helpful to permeation increasing and gas flow was brought up, which can optimize the design of gas drainage. Furthermore, the result of the research can provide experiment, theory, and technology support to gas drainage in deep low-permeability high gas coal seam mining.

项目采用实验室多尺度多场耦合试验、现场试验与监测、多场耦合理论分析与数值模拟相结合的方法，针对深部低渗高瓦斯煤层开采中瓦斯抽采方面的基础理论和关键科学问题进行研究，探索深部低渗高瓦斯煤层瓦斯安全高效抽采机理。通过多场耦合条件下低渗煤岩变形及渗透机理的理论与试验研究，揭示深部多场耦合条件下低渗煤层瓦斯渗流机制，建立深部低渗煤岩渗透率理论模型。开展不同尺度下煤岩宏细观裂隙场演化规律的试验研究，建立多场耦合作用下煤岩体损伤断裂及瓦斯渗流理论模型。通过“大型多场耦合含瓦斯煤采掘模拟试验系统”，研究低渗煤岩体水压致裂及深孔预裂爆破增渗机理。根据建立的损伤断裂渗流模型及数值模拟结果，研究煤岩体卸压区内的破断规律及瓦斯流动与富集规律，提出有效的增渗及瓦斯导向流动方法，优化瓦斯抽采设计。研究成果将为深部低渗高瓦斯煤层开采中的瓦斯抽采提供理论与技术支撑。

目前，我国针对深部低渗高瓦斯煤层开采中瓦斯抽采方面的相关基础研究还不够系统深入，亟待在瓦斯抽采机理的基础研究方面取得突破。本项目通过实验室试验、现场试验与监测、多场耦合理论分析与数值模拟相结合的手段，系统地进行了深部低渗高瓦斯煤层开采中的瓦斯抽采理论与技术研究，取得了如下创新性研究成果：.1. 成功研制了由“多功能真三轴流固耦合试验装置”、“多场耦合煤与瓦斯共采模拟试验系统”、“三向加载大型三维相似模拟试验系统”、“煤岩CT热流固耦合试验装置”和“煤岩热流固耦合试验装置”等7套装置组成的“深部低渗透高瓦斯煤层瓦斯抽采基础研究系列试验系统”，为深入系统地开展深部低渗透高瓦斯煤层瓦斯抽采基础研究提供了先进的试验手段与方法。.2. 利用“深部低渗透高瓦斯煤层瓦斯抽采基础研究系列试验系统”，开展了煤岩在一维、常规三轴、真三轴等应力条件下的多物理场耦合系列试验研究。在此基础上，建立了考虑采动应力影响和真三轴各向异性的煤岩渗透率模型，提出了含瓦斯煤岩热流固耦合模型，结合现场测试与数值模拟，揭示了深部煤岩体在应力场、渗流场、温度场等多场耦合作用下的破断机理及瓦斯运移规律，为煤与瓦斯安全高效开采提供了理论基础。.3. 开展了真三轴应力条件下CO2及水压致裂的试验和理论研究，获得了真三轴应力条件下气、水致裂煤岩起裂压力、方向及裂纹扩展规律等煤岩致裂增渗的关键参数，为提高煤层瓦斯抽采率提供了理论和技术基础。提出了“CO2相变致裂-水力压裂耦合致裂增渗技术”，并在现场进行了应用，取得了良好的效果。.项目成果已出版专著2部，发表学术论文57篇。项目执行期间新申请国家发明专利76项，其中已获得授权国家发明专利47项。项目相关研究内容获得省部级奖励一等奖3项、二等奖1项。项目组已培养出站博士后2人、毕业博士生14人、毕业硕士生20余人。