复杂裂缝系统不定常渗流研究

发布时间：2018-08-01 12:07

【摘要】：裂缝问题现阶段已经成为国内外研究热点问题之一,无论是页岩气、致密气、还是煤层气藏都是微裂缝较为发育的气藏。而油藏-裂缝耦合问题一直是比较复杂的课题,国内外大部分学者采用数值模拟方法及半解析方法进行研究。本文采用无网格半解析技术在拉普拉斯空间进行求解,一方面由于是半解析解,获得的结果更为可靠,一些早期现象是数值模拟计算所不能比拟的,另一方面,本文所有模型均在拉普拉斯空间进行耦合求解,由于不用考虑时间变量,算法会更加简单快速。本文建立模型较为全面,包括了以往文献中提到的各种模型(水平裂缝,垂直裂缝,椭圆裂缝及多裂缝系统),但有一些结果文献中未见报道,也有一些模型是对原有模型进行改进。在垂直裂缝方面,本文提出了非常规气藏有限导流不对称裂缝,分析了裂缝不对称性对典型曲线的影响,也进行了流动特征分析。由于煤层气藏的面割理与Rl割理之间常常表现为各向异性,基于此建立了煤层气藏各向异性数学模型,运用角度马修斯及径向马修斯函数得到了各向异性模型的解,分析了各向异性对典型曲线的的影响。在水平裂缝方面,本文提出了水平裂缝与空间无限大油藏耦合模型,并在裂缝中考虑了非达西效应,建立了典型曲线,分析了非达西因子对典型曲线的影响。本文的模型可以扩展成梯形裂缝,以及不同外边界的耦合解可作为本论文的后续研究。在复杂裂缝系统的研究中,首先提出了矩形油藏多段压裂水平井不稳定数学模型,将压裂水平井的流动段分成六段,分别是双线流,第一线性流,第一径向流,第二线性流,第二径向流,边界流。建立了碳酸岩油藏多分支裂缝数学模型并进行耦合求解,模型可以简化成传统常规油藏多分支裂缝模型(体积压裂模型)。四分支裂缝的结果和数值模拟Eclipse的结果进行验证。建立了碳酸岩油藏多分支裂缝典型曲线,将流动分为五个区域,分别是双线性流区域,线性流区域,从溶洞到介质窜流区域,从基质到裂缝窜流区域,径向流区域。最后,本文建立了有限导流随机裂缝数学模型,给出了随机裂缝模型的耦合解,给出了一些随机裂缝模拟的例子,随机裂缝将成为裂缝模拟的主要研究方向。
[Abstract]:At present, fracture problem has become one of the hot research issues at home and abroad, whether shale gas, dense gas, or coalbed gas reservoirs are more developed gas reservoirs with micro-fractures. The problem of reservoir-fracture coupling is always a complicated subject. Most scholars at home and abroad use numerical simulation method and semi-analytical method to study it. In this paper, the meshless semi-analytical technique is used to solve the problems in Laplace space. On the one hand, the results obtained are more reliable because they are semi-analytical solutions, and some early phenomena can not be compared with numerical simulation, on the other hand, All the models in this paper are solved by coupling in Laplacian space. The algorithm is simpler and faster because time variables are not considered. In this paper, the model is more comprehensive, including all kinds of models (horizontal fracture, vertical crack, elliptical fracture and multi-fracture system) mentioned in previous literatures, but some results are not reported in the literature. There are also some models to improve the original model. In terms of vertical fractures, this paper puts forward the finite flow asymmetry fractures in unconventional gas reservoirs, analyzes the influence of fracture asymmetry on typical curves, and analyzes the flow characteristics of unconventional gas reservoirs. Due to the anisotropy between surface cleavage and Rl cleat of coalbed methane reservoir, a mathematical model of anisotropic coalbed methane reservoir is established, and the solution of the anisotropic model is obtained by using angle Matthews and radial Matthews function. The influence of anisotropy on typical curves is analyzed. In the aspect of horizontal fracture, the coupling model between horizontal fracture and spatial infinite reservoir is put forward in this paper. The non-Darcy effect is considered in the fracture, the typical curve is established, and the influence of non-Darcy factor on the typical curve is analyzed. The model of this paper can be extended to trapezoid cracks and coupled solutions of different outer boundaries can be used as a follow-up study of this paper. In the study of complex fracture system, the unstable mathematical model of multi-section fracturing horizontal well in rectangular reservoir is proposed. The flow section of the fractured horizontal well is divided into six sections, namely, two-line flow, first linear flow, first radial flow, and second linear flow. Second radial flow, boundary flow. The mathematical model of multi-branched fractures in carbonate reservoir is established and solved by coupling. The model can be simplified into a conventional multi-branch fracture model (volume fracturing model). The results of four-branch fracture and numerical simulation of Eclipse are verified. The typical curve of multi-branched fractures in carbonate reservoir is established and the flow is divided into five regions: bilinear flow region, from cavern to medium channeling region, from matrix to fracture channeling region, radial flow region. Finally, the mathematical model of finite diversion random fracture is established, the coupling solution of stochastic fracture model is given, and some examples of stochastic crack simulation are given. Random crack will be the main research direction of crack simulation.
【学位授予单位】：中国地质大学(北京)
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TE31

【相似文献】