【作者】 付玉；

【导师】 郭肖；

【作者基本信息】 西南石油学院 ， 油气田开发工程， 2004， 硕士

【摘要】 大量实验研究和现场应用证实了煤层气藏开采过程中经历解吸、扩散、渗流过程，储层孔隙度和渗透率随压力变化。而经典渗流规律不再适用于煤层气复杂流动特征和储层地质特征，针对其局限性，建立了一个合理的、能正确反应煤储层孔隙度和渗透率变化的煤层气储层数学模型。 本文基于国内外文献调研，分析了煤层气储集、运移和产出机制，针对煤层气开采经历的解吸、扩散、渗流等复杂流动过程，建立了三维、双重介质、气-水两相数学模型，该模型考虑了非平衡拟稳态吸附、煤层气解吸后煤基质收缩变化对储层物性参数的影响：计算煤层气井产量时，推导出压裂水平井的产能公式，公式考虑了煤层气储层非均质性、裂缝部分穿透储层、裂缝条数等因素对水平井产能的影响。该模型采用IMPES方法数值求解，并借助计算机技术开发了具有友好界面的煤层气储层数值模拟软件CBM-RS1.0，实现了数学模型的数值求解和计算机求解，应用该模拟器研究了煤基质收缩对储层孔隙度、渗透率和井产能的影响，分析了基质收缩模型的敏感性，对比了压裂水平井和直井开采煤层气的效果。主要研究成果： 1 基于固体变形理论与固体表面能理论，建立煤基质收缩或膨胀变形与煤裂隙渗透率和孔隙度关系的数学模型。该模型避免了直接用煤体收缩系数和ε_l/β来计算储层孔隙度和渗透率所引起的误差。 2 基于位势理论和叠加原理，建立煤层气储层压裂水平井产能计算模型。该模型考虑了煤层气储层非均质性、裂缝部分穿透储层、裂缝条数等因素对水平井产能的影响。 3 建立三维、双重介质、气—水两相煤层气储层模拟的数学模型，模型考虑了非平衡拟稳态吸附、煤基质收缩对储层孔隙度和渗透率的影响，并进行数值求解。修改黑油模拟程序BOAST Ⅱ源代码，发展了一个煤层气模拟器，该模拟器突破目前大多数煤层气模拟软件不能考虑煤基质收缩影响所存在的局限性。 4 采用可视化编程工具Compaq Visual Fortran 6.5和Visual Basic 6.0开发煤层气储层模拟器主程序及应用界面，运用相关软件对计算结果进行处理。更多还原

【Abstract】 Coal seam geologic features and Coalbed gas flow characteristics through porosity media are so complex that conventionally classical percolation law are not suitable for coalbed gas reservoir. Large numbers of experimental studies and coalbed gas field applications have proved that three processes, coalbed gas adsorption, diffusion, percolation in the methane producing process, the changes in porosity and permeability are affected by coal matrix shrinkage and effective stress alteration.On the basis of the domestic and abroad literatures researches, the mechanisms of the storing, migrating and producing for coalbed gas and the complex exploiting procedure of coalbed gas are analyzed, a three-dimensional, dual-porosity, two-phase mathematical model for simulating methane producing process is developed; in model non-equilibrium, pseudo-steady sorption and the changes of reservoir parameters with the coal matrix shrinkage are taken considerate. In another hand, this complex mathematical model is approximated and solved by finite-difference and implicit pressure and explicit saturation method (IMPES). Coalbed Gas Reservoir Simulation software in 1.0 version (CBR-MS 1.0) with friendship interface of input and output is developed and the corresponding numerical and computer solution of mathematical model were set up. The productivity formulae of fractured horizontal well when calculate the production of coalbed gas well are derived, many factors effect the production of coalbed gas well are analyzed by the formulae; the simulator are applied to study the effect of coal matrix shrinkage on reservoir porosity, permeability and the well productivity, the sensibility of coal matrix shrinkage model are analyzed, the exploitation effect of fractured horizontal well and vertical well are compared.The acquired achievements are as follows: On the basis of the theories of solid deformation and solid surface energy, developing a coal matrix shrinkage model that indicates the effects of the deformation of coal matrix shrinkage on the porosity and permeability of fractures. The model avoids the reservoir porosity and permeability error that are brought by the inaccurate coal matrix coefficient and 1/ . On the basis of the theories of potential function principles and superposition principal, the horizontal well productivity formula is developed. Anisotropy of reservoir matrix, number of fractures and fractures of fully or partially penetrating in the formation and so on are considered in the formulae. A three-dimensional, dual-porosity, two-phase mathematical model developed,non-equilibrium, pseudo-steady sorption and the effects of the deformation of coal matrix shrinkage on the porosity and permeability of fracture are considered, and numerical solution is derived. Coalbed gas reservoir simulator in 1.0 version is developed by modifying source code of Black Oil Simulation procedure BOAST II, the simulator breaks through the limitation of others coalbed gas reservoir simulation software that don’t take coal matrix shrinkage into account. The main procedure and the friendship interface of the simulator are programmed by Visual Basic in 6.0 version and Compaq Visual Fortran in 6.5 version, the calculated results are dealt with by corresponding software.更多还原