页岩气藏渗流理论及单井数值模拟研究

发布时间：2018-04-02 20:37

本文选题：页岩气　切入点：渗流机理　出处：《西南石油大学》2015年硕士论文

【摘要】：页岩气在成藏、赋存、渗流等方面都不同于常规油气藏,开采方式与常规油气也有明显区别。但由于技术所限,我国页岩气藏开发尚处于起步阶段,特别是对页岩气藏渗流机理的认识仍然不足。这就极大地制约了对页岩气藏经济、有效地开发。因此,探讨页岩气藏开采过程中的复杂渗流问题,对页岩气开采技术的发展有着重大的理论意义。同时页岩气的利用与开发又可以解决化石能源对环境破坏的大部分问题。因此,探讨页岩气藏开采过程中的复杂渗流问题,对我国经济发展和环境保护又有着重大的现实意义。鉴于页岩气藏非线性渗流理论与数值模拟技术是有效开发页岩气藏的前提和基础。本文针对页岩气在运移过程中的吸附、解吸、扩散、渗流等特征,建立了页岩气藏气-水两相渗流的数学模型和数值模型。借助以上模型,深刻地认识并分析了页岩气藏的渗流机理。而后应用Eclipse数值模拟软件的页岩气模块对页岩气藏单井进行了数值模拟研究,论证了气藏自身参数和工程参数对产气量及采收率的影响。利用正交试验法判断了各敏感性参数对页岩气藏累计产气量影响的主次顺序。本文取得的主要研究成果如下： (1)在大量国内外文献调研的基础上,对页岩储层特征、储集特征、渗流机理进行了系统深入地研究,为页岩气藏的开发动态特征描述奠定了理论基础。 (2)基于页岩气藏渗流特点,建立了考虑Langmuir吸附作用、Fick扩散作用和达西渗流的页岩气藏储层气-水两相渗流数学模型。对数学模型采用全隐式差分方法建立了描述页岩气藏气-水两相流动规律的数值模型。 (3)应用Eclipse数值模拟软件建立了页岩气藏单井数值模拟模型,对气藏自身参数进行了敏感性分析。结果表明：随着裂缝系统渗透率的增加、Langmuir压力的增加、Langmuir体积的增加、窜流系数的增加、扩散系数的增加,水平井产气量逐步上升；基质渗透率对产气量几乎没有影响。运用极差法判断出各敏感性参数对页岩气藏产气量的影响顺序为：裂缝渗透率、窜流系数、扩散系数、Langmuir体积、Langmuir压力、基质渗透率。 (4)应用Eclipse数值模拟软件对工程参数进行了敏感性分析。结果表明：随着井型垂直角的增加,单井产气量逐步上升,直井由于产量过低无法完成页岩气藏的商业化生产；随着水平井井距的增加,单井产气量逐步上升,但采收率逐渐下降；随着水平段长度的增加、裂缝半长的增加及井底流压的降低,单井产气量逐步上升。运用极差法判断出各敏感性参数对页岩气藏产气量的影响顺序为：井底流压、裂缝半长、裂缝间距、水平井井距、水平段长度。
[Abstract]:Shale gas is different from conventional oil and gas reservoirs in reservoir formation, occurrence and percolation.However, due to the limitation of technology, the development of shale gas reservoirs in China is still in the initial stage, especially the understanding of the seepage mechanism of shale gas reservoirs is still insufficient.This greatly restricted the shale gas reservoir economy and effective development.Therefore, it is of great theoretical significance for the development of shale gas recovery technology to discuss the complex seepage problem in the process of shale gas reservoir exploitation.At the same time, the use and development of shale gas can solve most of the environmental damage problems caused by fossil energy.Therefore, it is of great practical significance for the economic development and environmental protection of China to discuss the complex seepage problem in the process of shale gas reservoir exploitation.In view of the nonlinear seepage theory and numerical simulation technology of shale gas reservoir is the premise and foundation of effective development of shale gas reservoir.Aiming at the characteristics of adsorption, desorption, diffusion and percolation of shale gas during migration, a mathematical model and a numerical model of gas-water two-phase percolation in shale gas reservoir are established in this paper.With the help of the above model, the seepage mechanism of shale gas reservoir is deeply understood and analyzed.Then the single well of shale gas reservoir is numerically simulated by using the shale gas module of Eclipse software, and the effects of gas reservoir parameters and engineering parameters on gas production and recovery are demonstrated.The primary and secondary order of the influence of the sensitivity parameters on the cumulative gas production of shale gas reservoirs is determined by the orthogonal test method.The main research results obtained in this paper are as follows:1) on the basis of a large number of domestic and foreign literatures, the characteristics of shale reservoir, reservoir characteristics and percolation mechanism are studied systematically and deeply, which lays a theoretical foundation for the description of shale gas reservoir development dynamic characteristics.Based on the percolation characteristics of shale gas reservoir, a mathematical model of gas-water two-phase percolation in shale gas reservoir considering Langmuir adsorption and Darcy percolation is established.A numerical model of gas-water two-phase flow in shale gas reservoir is established by using the fully implicit difference method for the mathematical model.The single well numerical simulation model of shale gas reservoir is established by using Eclipse software, and the sensitivity of gas reservoir parameters is analyzed.The results show that with the increase of permeability of fracture system and the increase of Langmuir pressure, the volume of Langmuir, the coefficient of channeling flow and the coefficient of diffusion increase, the gas production of horizontal well increases gradually, and the matrix permeability has little effect on gas production.By using the range method, the order of influence of each sensitive parameter on gas production of shale gas reservoir is as follows: fracture permeability, channeling coefficient, diffusion coefficient, Langmuir volume and Langmuir pressure, matrix permeability.4) sensitivity analysis of engineering parameters is carried out by using Eclipse numerical simulation software.The results show that with the increase of vertical angle of well type, the gas production of single well increases gradually, and the commercial production of shale gas reservoir can not be completed in straight well because of its low production rate, and the gas production rate of single well increases gradually with the increase of horizontal well spacing.With the increase of horizontal section length, the increase of fracture half length and the decrease of bottom hole flow pressure, the gas production rate of single well increases gradually.By using the range method, the order of influence of each sensitive parameter on gas production of shale gas reservoir is as follows: bottom hole flow pressure, fracture half length, fracture spacing, horizontal well spacing and horizontal section length.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE312

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