构造煤各向异性渗透率张量定量表征及多尺度演变行为研究

This project will be finished by combining laboratory experiment, CT reconstruction, model development, and computer programming. Anisotropic permeability characteristics of tectonically deformed coals will be investigated by measuring the axial permeability of cubic samples. Experiments will be conducted to investigate the dynamic responses of the anisotropic permeability characteristics of tectonically deformed coals to effective stress change, gas adsorption/desorption, and both mechanisms. A computer code will be programmed to quantitatively represent and visualize the anisotropic permeability tensor of tectonically deformed coals under various observation dimensions. This code will be used to deconstruct the CT reconstruction model of fracture network of tectonically deformed coals. The anisotropic permeability tensor of tectonically deformed coals will be quantitatively represented under various observation dimensions and coordinate systems. With the obtained anisotropic permeability tensors, the following results can be expected:.(1) Deep demonstration of the multi-scale evolution behavior of the anisotropic permeability tensor, especially the main permeability tensor of tectonically deformed coals..(2) Detection of the impacting modes of low-scale anisotropic permeability tensor on the high-scale counterpart for tectonically deformed coals..(3) Explanation of the controlling mechanism of fracture network structure on the multi-scale evolution behavior of the anisotropic permeability tensor..(4) Further investigation of the anisotropic permeability tensor of tectonically deformed coals in higher scales..With the aforementioned four results, this project is intended to offer new insights into permeability evaluation, gas drainage borehole design and parameter determination, and coal and gas outburst in tectonically deformed coals.

采用室内实验、CT重构、理论建模和计算机编程相结合的方法，揭示构造煤立方体试样轴向渗透率各向异性特征，阐明有效应力变化、瓦斯吸附/解吸以及两者共同作用下构造煤立方体试样轴向渗透率各向异性动态响应规律；编制构造煤各向异性渗透率张量多尺度定量表征与三维可视化程序，解析构造煤裂隙网络结构CT重构模型，定量表征不同观测尺度和不同观测坐标系下的构造煤各向异性渗透率张量，深入揭示构造煤各向异性渗透率张量尤其是主渗透率张量多尺度演变行为特征，辨识构造煤低尺度各向异性渗透率张量对高尺度各向异性渗透率张量的影响模式，阐明构造煤裂隙网络结构对各向异性渗透率张量多尺度演变行为的控制作用，进而探究更大尺度空间内构造煤各向异性渗透率张量的典型特征，以期为构造煤渗透性评价、构造煤瓦斯抽采钻孔设计与工艺参数选择，以及构造煤与瓦斯突出预测与防治提供参考。

研究煤层各向异性渗透率张量不仅是全面评价和深入认识煤层渗透性的前提，也可以指导煤层气开发、煤层瓦斯抽采以及煤与瓦斯突出预测与防治工程实践，利用煤渗透率的各向异性，发挥最大主渗透率的正面作用，削弱最小主渗透率的负面作用。通过本项目的研究，自主研发了煤渗透率张量实验测试平台和测试方法，实现了具有复杂裂隙结构的构造煤渗透率张量精准测试与定量表征；利用该实验测试平台，研究了有效应力变化和瓦斯吸附过程中构造煤主渗透率演化行为，揭示了构造煤各向异性主渗透率演化行为的差异，阐明了有效应力变化和瓦斯吸附对构造煤主渗透率演化行为差异性的影响机理；构建了考虑真是构造煤裂隙结构复杂性的渗透主轴方向与地应力主轴方向通常处于非正交状态的主渗透率演化模型，揭示了渗透主轴方向与地应力主轴方向非正交程度对主渗透率演化行为的影响机制；设计了基于裂隙结构图像的主渗透率张量定量表征算法，并用C++语言编制了解算程序；利用该程序构造煤裂隙结构图像的主渗透率张量进行了定量计算，得到了各个图像的主渗透率值和主渗透率方向、对比分析了不同尺度裂隙结构图像主渗透率值和主渗透率方向的差异性，揭示了构造煤主渗透率张量多尺度演变行为。项目研究成果为构造煤渗透性评价、构造煤瓦斯抽采钻孔设计与工艺参数选择，以及构造煤与瓦斯突出预测与防治提供了支撑。