深部煤层气系统及其能量动态平衡机理研究

The deep coal seam is at relatively high temperature, high pressure, and high in-situ stress environment, hence, thegas accumulation and permeabilityevolutionof coal reservoir, coalbed methane (CBM)adsorption-desorption-diffusion-percolation balance relation, stress and strain behaviorof coal, and so on, tend to be more complex.The limited understanding of the occurrence mechanism and recoverabilityof deep CBMseverely impeded its development in China.In order to solvethe key scientific issue of deep CBM occurrence mechanism, this project intends to adopt analysis principles and method of CBM system matter and energy dynamic balance. Through comparative analyses of the east margin of Ordos basin and typical deep CBM system, combined with the experimental analyses and physical simulation as well as various methods,thisproject mainly discussedand finally revealed the gas accumulation,permeability evolution,coal rock mechanicalbehaviors,and the CBMadsorption-desorption-diffusion-percolationbalance relationship of deep CBM reservoir, under the condition of high temperature, high pressure,high in-situ stress, and high burial depth, as a result, formed the theoretical results of deep CBM occurrence mechanisminitially.In addition, through discussion on the resource recoverability as well as further investigation of theenergy release space and pathway of the deep CBM system (Deep reservoir reconstruction feasibility), this project also revealed the synergetic development and dynamic mechanism of deep coal reservoir gas accumulation, permeability, and resource recoverability.

深部煤层处在相对高温、高压、高地应力环境，煤储层储渗演化、煤层气吸附—解吸—扩散—渗流平衡关系、煤岩应力应变行为等趋于复杂。深部煤层气赋存机理及可采性认识不清，严重阻碍我国深部煤层气开发。项目拟采用煤层气系统物质与能量动态平衡分析原理和方法，针对深部煤层气赋存机理这一关键科学问题开展研究，通过鄂尔多斯盆地东缘与典型深部煤层气系统的剖析，结合实验测试、物理模拟等手段，重点探讨深部高温、高压、高地应力环境中煤储层储渗演化、煤层气吸附—解吸—扩散—渗流平衡关系、应力应变岩石力学行为，揭示深部地温场、流体压力场、应力场制约下的煤储层储渗特点、煤层气吸附—解吸—扩散—渗流动态平衡、煤岩力学性质，形成深部煤层气赋存机理理论成果。进一步通过深部煤层气系统能量释放空间及释放途径（深部储层可改造性）研究，探讨资源可采性，揭示深部煤储层储集性、渗透性、资源可采性协同发展及其动力学机制。

深部煤层处于高地应力、高地层温度和高流体压力的地质环境下，导致煤层非均质性强、煤层气可采性差、煤储层改造难度大等问题。本项目以鄂东地区为重点研究区，采用煤层气系统物质与能量动态平衡分析原理和方法，揭示深部煤层储集性、可采性、可改造性协同发展动力学机制，取得以下主要成果：①基于深部煤储层地质条件的综合研究，阐释了深部煤层气的科学内涵与定义，探讨了地应力、储层压力、地层温度与煤层埋深的相互关系，查明了不同地质单元深部煤储层物性显现特征及主控因素；②针对深部煤储层相对高温和高压的地质特点，通过吸附势理论揭示了煤与甲烷吸附解吸平衡关系及能量动态变化规律，阐明了温压耦合作用对煤层气吸附—解吸—扩散—运移的影响，揭示了深部煤层气赋存机理，形成了深部煤储层含气性预测理论和方法；③探查了深部煤岩力学性质与应力作用机制，结合宏观构造动力学条件分析，揭示了深部煤储层岩石力学与孔渗系统变化的地质过程与效应，在深部地温场、压力场、应力场制约的解吸—扩散—渗流平衡关系认识基础上，揭示了深部煤层气体系能量释放空间与煤层气资源可采性关系；④利用不可逆热力学理论，构建了煤岩的弹塑性损伤本构模型，探讨了深部煤储层压裂裂缝拓展规律，总结了埋深控制下压裂裂缝诱导煤储层天然裂隙的延伸规律，结合典型深部区块煤层气井压裂微地震检测结果，系统剖析了深部煤储层压裂改造的地质选择性。研究成果搭建了深部煤层气富集成藏与地质探测的理论架构，揭示了深部煤层气系统发育的地质特征及其控制作用，创新提出了能量平衡制约下的深部煤层气形成演化和产出机制，为深部煤层气勘探开发奠定了地质理论基础和技术选择依据。截止到2020年底，项目资助发表论文106篇，其中SCI检索论文80篇、EI检索论文11篇；授权国家发明专利25项、专利成果转化1项；出版专著6部；获得国家科技进步二等奖1项、中国煤炭协会科技一等奖1项、中国石油化工协会科技一等奖1项、中国石油化工自动化应用协会科技进步二等奖1项、贵州省科技进步三等奖1项。