深部煤层CO2封存过程中煤体吸附/解吸变形效应及气体运移规律研究

According to the practical needs of basic theory on the carbon dioxide storage in deep coal seam, it will consider the combined effect of moisture, temperature, gas pressure, gas component and external stress , and adopt laboratory study, mathematical and mechanical theoretical in this project to study the adsorption/desorption-induced deformation effects of coal body and gas migration rule. Based on the adsorption / desorption-induced deformation and swelling stress experiment under the combined effect, it is aiming at researching on the dynamic evolutional mechanism of adsorption /desorption-induced deformation and swelling stress of coal body, building the multi-factor model between the related factors and gas-induced deformation / swelling stress, and obtaining the quantitive relationship between swelling stress and deformation. Moreover, according to the result, simulation experiment for carbon dioxide storage will be conducted, which can simulate the gas injection, competitive adsorption, replacement and flooding process and mechanical performance, to analyze the dynamic evolution rule of coal body permeability, build the Thermal-Hydraulic-Mechanical coupling model considering the effect of adsorption / desorption-induced deformation effects, and study the gas migration law in the process of carbon dioxide storage in deep coal seam. The results of this project can play an important role in understanding the mechanism of the carbon dioxide storage and the CH4 displacement in the deep buried coal seam.

针对深部煤层封存CO2基础理论的实际需要，综合考虑水分、温度、气体压力、气体组分和外应力等因素的影响，采用实验室研究和数学力学理论分析相结合的方法，研究深部煤层CO2封存过程中煤体吸附/解吸变形效应及气体运移规律。本项目旨在通过多因素综合影响下的吸附/解吸变形及膨胀应力实验，研究深部煤体吸附/解吸变形及膨胀应力动态演化机理，建立考虑多因素影响的变形及膨胀应力计算模型，并获得膨胀应力与变形之间的定量关系；在此基础上，开展模拟热流固耦合作用下气体的注入、竞争吸附、置换、驱替过程以及相关力学表现的深部煤层CO2封存模拟实验，分析深部煤体渗透性动态演化规律，建立考虑吸附/解吸变形效应的热流固耦合运移模型，探讨深部煤层CO2封存过程中的气体运移规律。研究成果对深刻认识深部煤层CO2封存及其驱替CH4机理具有重要作用，并为优化深部煤层CO2封存和煤层气开发方案奠定理论和技术基础。

针对深部煤层封存CO2基础理论的实际需要，本项目采用实验室研究和数学力学理论分析相结合的方法，研究深部煤层CO2封存过程中煤体吸附/解吸变形效应及气体运移规律。主要研究内容有：1）开发了煤层高压吸附解吸（变形）试验系统，实现多个样品同时进行吸附/解吸气体量和变形量测试功能。2）开展了不同因素影响下的吸附/解吸量与变形量同步测试实验，分析了吸附/解吸特征、变形特征及两者相互关系，系统梳理了吸附/解吸变形机理，建立了基于实验研究的吸附/解吸变形计算模型。3）开展了煤体吸附/解吸膨胀应力实验，分析了吸附/解吸膨胀应力动态演化特征，探讨了吸附/解吸膨胀应力和变形的关系，建立了膨胀应力计算模型。4）开发了煤层注CO2置换驱替CH4物理模拟实验装置，开展了不同注气压力下注CO2气体驱替CH4实验研究，探讨了注气驱替过程中瓦斯扩散系数的变化规律和气体运移机理。5）综合考虑应力场、渗流场和温度场的耦合作用，建立了考虑吸附/解吸变形效应的煤层CO2封存过程中的热流固耦合运移模型。6）针对现有实验装置的不足，进一步设计了一种煤岩裂隙腔内三维粒子图像测速试验系统和一种煤岩模拟试验用真三轴压力室及其试验方法。研究成果对深刻认识深部煤层CO2封存及其驱替CH4机理具有重要作用，并为优化深部煤层CO2封存和煤层气开发方案奠定一定理论基础。