煤裂-孔性双重介质中煤层气吸附/解吸运移机理的分形研究

项目名称： 煤裂-孔性双重介质中煤层气吸附/解吸运移机理的分形研究

项目编号： No.41472128

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 天文学、地球科学

项目作者： 金毅

作者单位： 河南理工大学

项目金额： 92万元

中文摘要： 探明双重孔隙结构对煤层气运移的控制作用，发掘其吸附/解吸诱发机制,再现多场耦合的瞬变流过程及其对储层输运属性的影响，是理解煤层气运移机理并实现其产能准确评估的基础。本课题拟以分子动理论为多孔介质流基础物理的发掘工具，于孔隙尺度分析煤岩基质分形孔-渗关系及端面粗糙复合形貌空间下裂-渗方程，并依据割理/裂隙的空间分布解析建立裂-孔性双重介质的孔-渗分形关系；在此基础上，结合煤层气吸附/解吸实验结果，借鉴光电效应来分析甲烷的吸附/解吸诱发机制，并推演煤介质孔隙空间膨胀/收缩的岩石力学特征；进而采用格子弹力模型来表征孔隙空间的动态形变，并发展一种耦合吸附/解吸过程的格子波尔兹曼渗流控制体系，利用流体粒子间的碰撞来实现多场的有机耦合及瞬变运移过程的模拟，最终建立煤层气的渗流模型。课题关键问题的解决，有望在煤层气渗流理论方面有所突破，为煤层气开采潜力评估及高效开发利用提供理论依据和技术支持。

中文关键词： 瞬变流；吸附/解吸过程；双重介质；分形特征；孔-渗关系

英文摘要： To better understand the migration mechanism of coalbed methane(CBM) and accurately assess its productivity, we focus our attention on three basic problems existing in the seepage of CBM: the effect of dual-porosity pore structure with fractal behaviors on the permeability of coal reservoir, the inducing mechanism of the adsorption/desorption process for methane, and the characteristics of the transient flow resulting from multi-field coupling effect and its influence on the transport property of coal. In this project, the kinetic theory is adopted as the primary mining tool to explore the basic physics of porous media flow. As a critical step in the current project, we will first investigate the fractal pore-permeability relationship as well as the fracture-permeability relationship in the fracture composite topography with mismatched rough surfaces，and then analytically derive the fractal pore-permeability relationship of coal media with dual-porosity based on the spatial distribution of the cleat/fracture system and the fractal matrix pore structure. Sequentially, with the results of the adsorption/desorption experiments, we will analogically explore the inducing mechanism of such a process by borrowing the photoelectric effect theory, and analytically derive the rock mechanics characteristics of expansion and contraction in pore space. By the lattice springs model (LSM), we will also characterize the dynamic micro deformation in pore space, and develop a lattice Boltzmann model to govern the flow of CBM, which couples the adsorption/desorption processes. Furthermore, we will carry out the interaction between the LSM and LBM systems by the collision operation among fluid particles,and simulate the organic coupling of multiple fields and the process of transient flow. Based on the transient flow of CBM, we will analyze the effect of multi-fields and ultimately establish the seepage law. The solutions to these key issues in this study may bring about some breakthroughs in the seepage theories of coalbed methane, thus laying the theoretical foundation and providing technical support for the exploitation potentiality evaluation of CBM as well as for its highly efficient exploitation and utilization.

英文关键词： tansient flow;adsportion/desorption process;dual-porosity media;fractal characteristics;permeability-pore relationship