煤层气井水力压裂能量传递与均衡消突机理

The hydraulic fracturing of coalbed gas well is the main measure for the improvement and penetration of coal reservoir, and one of the main measures to eliminate the prominent danger in coal seam. The results show that the results are influenced by the physical properties of coal reservoir, the redistribution of stress field and the energy transfer and equilibrium of coal reservoir and etc. Previous studies have focused on the method, mechanism and influencing factors of coal reservoir fracturing, lack of hydraulic fracturing to coal reservoir energy accumulation and dissipation control and coal reservoir destruction mechanism, especially the ground fracturing corresponding to the underground area of the method and the effect of evaluation lack of effective theoretical support. This project selects No. 3 coal seam in Lu'an mining area of Qinshui Basin as the research object, adopts the method of laboratory experiment, numerical simulation and theoretical analysis, through the test experiment of coal body structure and rock mechanics characteristic after water leaching. The experiments of adsorption / desorption and desorption/ deformation of coal body after water leaching, the test and simulation of stress redistribution before and after fracturing, the numerical characterization of coal structure after fracturing, the model of energy accumulation and equalization transfer are established. The energy equilibrium model of coal reservoir under different fracturing scales is discussed. The physical and mechanical properties of coal body after coal seam fracturing are revealed, the essence of energy accumulation is related to equilibrium mode and outburst elimination index, and the mechanism of outburst suppression by hydraulic fracturing in coalbed methane wells is expounded. It provides theoretical guidance for underground coal and gas outburst prevention and metallurgy in the fracturing area of surface coalbed methane extraction well.

水力压裂即是煤储层改造、增透的主要措施，也是煤层消除突出危险性的主要措施之一。煤储层压裂改造后其消突效果受压裂后煤储层的物理性质、地应力场再分布及压裂过程中煤储层能量传递与均衡等因素影响。以往研究多集中在煤储层压裂增透方式、机理及其影响因素，缺乏水力压裂对煤储层能量聚积与耗散控制机理研究，尤其是压裂区对应井下区域的消突方式及消突效果判定缺乏有效的理论支撑。本项目选取潞安矿区3号煤层为研究对象，采用室内实验、数值模拟及理论分析相结合的方法，通过水浸后煤体结构及其岩石力学特性测试实验，水浸后煤体吸附/解吸与解吸/变形实验、压裂前后地应力再分布测试与模拟实验，建立压裂后能量聚积与均衡传递模型，探讨不同压裂尺度下煤储层能量均衡模型，揭示煤层压裂后煤体物理力学性质变化、能量聚积与均衡方式和消突指标关联实质，阐明煤层气井水力压裂消突机理，对煤层气井压裂区井下煤与瓦斯突出防治提供理论指导。