煤岩损伤演化与瓦斯渗流的热流固耦合分析.pdf

硕士学位论文 煤岩损伤演化与瓦斯渗流的 热流固耦合分析 Thermo-Fluid-Mechanical Coupling Analysis on the Damage Evolution of Coal and Rock and the Gas Seepage 作者张宁 导师程红梅 中国矿业大学 2017 年 5 月 万方数据 学位论文使用授权声明学位论文使用授权声明 本人完全了解中国矿业大学有关保留、使用学位论文的规定，同意本人所撰 写的学位论文的使用授权按照学校的管理规定处理 作为申请学位的条件之一， 学位论文著作权拥有者须授权所在学校拥有学位 论文的部分使用权，即①学校档案馆和图书馆有权保留学位论文的纸质版和电 子版，可以使用影印、缩印或扫描等复制手段保存和汇编学位论文；②为教学和 科研目的，学校档案馆和图书馆可以将公开的学位论文作为资料在档案馆、图书 馆等场所或在校园网上供校内师生阅读、浏览。另外，根据有关法规，同意中国 国家图书馆保存研究生学位论文。 （保密的学位论文在解密后适用本授权书） 。 作者签名 导师签名 年 月 日 年 月 日 万方数据 中图分类号 TD7 学校代码 10290 UDC 622 密 级 公开 中央高校基本科研业务费专项资金资助（2015XKMS094） 国家自然科学基金项目（51604260） 江苏省自然科学基金项目BK20140189 中国矿业大学 硕士学位论文 煤岩损伤演化与瓦斯渗流的 热流固耦合分析 Thermo-Fluid-Mechanical Coupling Analysis on the Damage Evolution of Coal and Rock and the Gas Seepage 作 者 张宁 导 师 程红梅 申请学位 工学硕士 培养单位 力学与土木工程学院 学科专业 固体力学 研究方向 裂隙岩体力学理论及应用 答辩委员会主席 李顺才 评 阅 人 二○一七年五月 万方数据 致谢致谢 在结束三年研究生的求学生涯之际，回首往昔，有过坎坷，有过奋斗，也有 许多值得珍惜的回忆。在此毕业论文完成之际，我要向所有关心、爱护和帮助我 的人们表示最诚挚的感谢和最美好的祝愿。 本论文是在导师程红梅的悉心指导之下完成的。三年来，导师渊博的专业知 识，严谨的治学态度，精益求精的工作作风，诲人不倦的高尚师德，以及朴实无 华的人格魅力对我影响深远。导师不仅教授了我怎么做科研，而且教授我做人的 道理， 让我终生受益匪浅。 在这里衷心地感谢导师程红梅对我的无微不至的关怀、 帮助以及细心周到认真的指导本论文从选题到完成，几易其稿，每一步都是在 导师的指导下完成的，倾注了导师大量的心血，在此我再次向我的导师表示深切 的谢意与良好的祝福 其次还要特别感谢高峰教授的科研团队给我提供了一个很好的工作平台， 感 谢王建国教授对我英文论文写作的指导，尤其要感谢滕腾博士对我论文写作、校 稿上的帮助以及学术上的指导。 感谢中国矿业大学杨玉贵副教授、 高亚楠副教授、 张志镇副教授、 刘嘉博士、 尚晓吉博士、张向向博士、薛熠博士、侯鹏博士、梁鑫博士、王惠民硕士、闫伟 城硕士等在论文完成过程中所给予的帮助。 特别感谢我的家人在我漫长的求学生涯中对我的理解和支持， 在今后的日子 里我要加倍努力来报答他们多年来的养育之恩。 另外， 我还要向文中及研究过程中引用到其学术论著及研究成果的前辈及同 行们表示感谢。 衷心感谢在百忙之中评审论文和参加答辩的各位专家、教授 张宁 2017 年 5 月 万方数据 I 摘摘 要要 煤层施工扰动或瓦斯卸压抽采会引起其周围煤岩产生破裂损伤。 损伤不仅使 得煤岩的结构属性和力学行为发生变化，还改变了煤岩的物性参数（如孔隙率、 渗透率等），最终对瓦斯赋存和运移均造成很大的影响。另外，瓦斯的运移不仅 改变了孔隙压力、有效应力以及煤层吸附膨胀变形，造成损伤的演化和积累，还 会带走一部分热量，使煤岩温度场发生变化。而温度的改变不仅会对煤岩中应力 分布造成影响，也会影响瓦斯的吸附性能以及扩散能力。因此煤层气抽采实际上 是煤岩损伤场、温度场、瓦斯渗流场的多场耦合过程，本文基于煤岩卸荷破坏损 伤理论、有效应力原理、多孔介质传质、传热机理和有限元的相关知识，通过理 论推导、数值模拟等手段对多场耦合作用下煤岩损伤场、瓦斯渗流场的分布及演 化规律进行了研究，这些成果对指导煤层瓦斯抽放设计、提高瓦斯抽采率等具有 极其重要的理论指导意义，具体研究内容如下 （1）将煤岩视为孔隙-裂隙双重介质，针对煤岩损伤破坏特征，用有效应变 定义了煤岩损伤变量，建立了考虑瓦斯压力、温度等影响的煤岩弹性损伤本构方 程，定量地描述了瓦斯抽采过程中煤岩的损伤演化过程。 （2） 根据损伤度来描述煤岩破碎程度和以煤岩破碎时的体应变服从 Weibull 分布来模拟煤岩的非均质性，建立了其孔隙率和渗透率演化的力学模型，在考虑 Fick 扩散、Knudsen 扩散以及滑脱效应对瓦斯流动的影响下，建立了瓦斯在损伤 煤岩中的扩散、渗流耦合方程；另考虑瓦斯流动引起的内能变化、吸附热及煤岩 变形对温度场的影响，建立了含瓦斯损伤煤岩的温度场控制方程。 （3）利用 FORTRAN 语言对有限元源程序进行了二次开发，编制了同时考 虑温度、瓦斯渗流、煤岩损伤变形的多场耦合分析程序，并对此程序的正确性进 行了验证。 （4）利用本程序对新庄孜煤矿瓦斯钻孔过程抽采进行了数值模拟。结果表 明抽采初期，钻孔周围煤体损伤影响范围在 3.5 m 左右，且随着抽放的不断进 行，煤体损伤影响范围逐渐扩大，同时煤层渗透性增大一个数量级。 （5）利用本程序对煤层气注热开采过程进行数值计算。结果表明注热能 显著提高瓦斯的解吸和扩散，提高产气速率和煤层气瓦斯开采效率。在定温边界 下，注热的影响范围在 0.5 m 左右，产气速率和产气量增产分别超过 110、90 以上。 该论文有图 35 幅，表 5 个，参考文献 112 篇。 关键词关键词煤岩损伤；瓦斯抽采；热流固耦合；有限元程序 万方数据 II Abstract The disturbance caused by coal seam construction or gas pressure relief will cause the damage of surrounding coal and rock. The damage not only makes the structure properties and mechanical behavior of coal and rock mass changes, but also change the physical parameters of coal and rock mass such as porosity, permeability, etc. are eventually caused a great impact on gas occurrence and migration. In addition, the migration of gas not only changes the pore pressure, the effective stress of coal seam and adsorption swelling deation, resulting in evolution and the accumulation of damage, but also takes away a part of the heat, changing the temperature field of coal seam. The change of temperature will not only affect the stress distribution of coal and rock mass, but also affect the adsorption and diffusion ability of gas. The gas drainage is actually a multi field coupling process of coal rock damage field, temperature field, seepage field of gas. Based on the coal unloading damage theory, the principle of effective stress and porous medium heat and mass transfer mechanism and finite element knowledge, this paper studies the distribution and evolution law of coal rock damage field and gas seepage field under multi field coupling by theoretical derivation and numerical simulation, which has important theoretical significance to guide the design of gas drainage and improve the gas drainage rate. The specific research contents are as follows 1 Coal rock is regarded as the pore fissure double medium, according to the characteristics of coal and rock damage, this paper defines the damage variable of coal and rock by the effective strain, and the constitutive equation of elastic damage of coal and rock, which takes into account the influence of gas pressure and temperature. 2 According to the degree of damage to describe the degree of fragmentation of coal, the Weibull distribution is used to simulate the heterogeneity of coal and rock. Based on the influence of Fick diffusion, Knudsen diffusion and slip effect on gas flow, the diffusion and seepage coupling equation of gas in coal seam is established. In addition, the influence of gas flow on the change of internal energy, heat of adsorption and deation of coal and rock on the temperature field is considered. 3 In this paper, the finite element source program is second developed using FORTRAN language and the multi field coupling is developed considering temperature, gas seepage and deation of coal rock damage analysis program, and 万方数据 III the correctness of this procedure is verified. 4 This program is used to simulate the process of gas drainage in the coal mine. The results show that, in the early stage of drainage, the damage range around the borehole is about 3.5 m, and with the continuous development of the drainage time, the damage scope of coal is gradually expanded, and the permeability of coal seam increases by an order of magnitude. 5 The program is used to calculate the process of CBM by heat injection. The results show that heat injection can significantly promote gas desorption and gas diffusion and improve the gas production rate and gas production efficiency. Under the constant temperature boundary, the influence range of heat injection is about 0.5 m, and the production rate of gas production and gas production are more than 110, more than 90, respectively. This dissertation includes 35 figures, 5 tables and cites 112 references. Keywords damage of coal and rock; gas drainage; thermo-fluid-mechanical coupling; finite element program 万方数据 IV 目目 录录 摘摘 要要 ...................................................................................................................... IIII 目目 录录 ...................................................................................................................... IVIV 图清单图清单 .................................................................................................................. VIIIVIII 表清单表清单 ...................................................................................................................... XIXI 变量注释表变量注释表 ............................................................................................................ XIIXII 1 1 绪论绪论 ........................................................................................................................ 1 1 1.1 研究背景及意义 ................................................. 1 1.2 国内外研究现状 ................................................. 2 1.3 本文研究内容与方法 ............................................ 12 1.4 技术路线与分析 ................................................ 13 2 2 煤岩损伤场、温度场和瓦斯渗流场的耦合理论煤岩损伤场、温度场和瓦斯渗流场的耦合理论 ................................................ 1515 2.1 引言 .......................................................... 15 2.2 损伤煤岩变形控制方程 .......................................... 15 2.3 瓦斯在煤层中的运移理论 ........................................ 20 2.4 含瓦斯煤温度场控制方程 ........................................ 25 2.5 非均质损伤煤岩的孔隙率、渗透率演化机理 ........................ 26 2.6 损伤煤岩热流固多场耦合模型 .................................... 28 2.7 本章小结 ...................................................... 28 3 3 损伤煤岩热流固耦合模型的数值解法损伤煤岩热流固耦合模型的数值解法 .............................................................. 3131 3.1 煤岩损伤变形的有限元方程 ...................................... 31 3.2 含瓦斯煤温度场有限元方程 ...................................... 35 3.3 瓦斯渗流的有限元方程 .......................................... 37 3.4 数值算法 ...................................................... 38 3.5 本章小结 ...................................................... 41 4 4 钻孔瓦斯抽采的数值模拟钻孔瓦斯抽采的数值模拟 .................................................................................... 4343 4.1 引言 .......................................................... 43 4.2 模型的建立 .................................................... 43 4.3 模型的验证和结果分析 .......................................... 46 4.4 钻孔瓦斯抽采的敏感性分析 ...................................... 53 万方数据 V 4.5 非均质损伤煤岩力学模型对瓦斯抽采的影响 ........................ 60 4.6 本章小结 ...................................................... 61 5 5 煤层气钻孔注热开采数值模拟煤层气钻孔注热开采数值模拟 .......................................................................... 6363 5.1 引言 .......................................................... 63 5.2 模型的建立 .................................................... 63 5.3 注热温度对产气效率的影响 ...................................... 63 5.4 煤层温度场的分布规律 .......................................... 65 5.5 注热温度对瓦斯压力分布的影响 .................................. 67 5.6 热膨胀系数对注热开采的影响 .................................... 74 5.7 本章小结 ...................................................... 74 6 6 结论与展望结论与展望 .......................................................................................................... 7777 6.1 结论 .......................................................... 77 6.2 展望 .......................................................... 78 参考文献参考文献 .................................................................................................................. 7979 附录附录 .......................................................................................................................... 8585 作者简历作者简历 ................................................................................................................ 102102 学位论文原创性声明学位论文原创性声明 ............................................................................................ 103103 学位论文数据集学位论文数据集 .................................................................................................... 104104 万方数据 VI Contents Abstract ........................................................................................................................ II Contents ..................................................................................................................... IV Drawing list ............................................................................................................ VIII Table list ..................................................................................................................... XI Variable table ........................................................................................................... XII 1 Introduction ............................................................................................................... 1 1.1 Research background and significance .................................................................... 1 1.2 Research status at home and abroad ........................................................................ 2 1.3 Research s and contents ............................................................................. 12 1.4 Technical route and analysis .................................................................................. 13 2 Coupling theory of damage field, temperature field and gas seepage field in coal and rock mass ..................................................................................................... 15 2.1 Introduction ............................................................................................................ 15 2.2 Damage mechanics model of coal containing gas ................................................. 15 2.3 Theory of gas migration in coal seam .................................................................... 20 2.4 Control equation of temperature field of coal containing gas ............................... 20 2.5 Mechanism of porosity and permeability evolution of heterogeneous damaged coal ............................................................................................................................... 26 2.6 Thermo-fluid-Mechanical coupling model of damaged coal seam ....................... 28 2.7 Brief summary ....................................................................................................... 28 3 Numerical Solution of Damage and Thermo Fluid Mechanical coupling Mathematical Model .................................................................................................. 31 3.1 Finite element equation for damage and deation of coal and rock ................ 31 3.2 Finite element equation of coal containing gas ..................................................... 35 3.3 Finite element equation of gas seepage ................................................................. 37 3.4 Numerical algorithm .............................................................................................. 38 3.5 Brief summary ....................................................................................................... 41 4 Numerical simulation of borehole gas drainage ................................................... 43 万方数据 VII 4.1 Introduction ............................................................................................................ 43 4.2 Establishment of Model ......................................................................................... 43 4.3 Model validation and results analysis .................................................................... 46 4.4 Sensitivity analysis of borehole gas drainage ........................................................ 53 4.5 Influence of heterogeneous damage coal rock mechanics model on gas drainage 60 4.6 Brief summary ....................................................................................................... 61 5 Numerical simulation of CBM by heat injection .............................................. 63 5.1 Introduction ............................................................................................................ 63 5.2 Model establishment .............................................................................................. 63 5.3 Effect of injection temperature on gas production efficiency ................................ 63 5.4 Distribution law of temperature field of coal seam ............................................... 65 5.5 Effect of injection temperature on gas pressure distribution ......................