基于体积源方法的双重介质渗流模型及其应用

发布时间：2018-03-18 16:09

本文选题：双重介质　切入点：体积源　出处：《西南石油大学》2015年博士论文　论文类型：学位论文

【摘要】：双重介质用以描述天然裂缝发育或体积压裂后形成裂缝网络的储层,其渗流理论广泛地应用于试井分析、产能评价、储层裂缝预测、开发方案优化等方面。国内外学者对双重介质渗流理论和应用已经有了大量的研究成果,但主要集中于直井、垂直裂缝井、水平井的渗流问题,而针对分段压裂水平井的研究较少,并且关于页岩气藏渗流问题的研究也待进一步深化。双重介质渗流问题的求解一般基于Laplace变换,结合相应的数值反演方法,可很好地应用于求解变流率生产等渗流问题;然而考虑水平井管流、高速非达西流动等压力和流量呈现非线性关系时的问题不能进行Laplace变换,使这类渗流问题成为传统双重介质渗流理论中难以克服的顽疾。此类非线性渗流问题在实空间的半解析求解方法已经非常成熟,主要通过离散时间求解每个时间段内的流量,由此可知实空间中的基本解是采用此类半解析方法进行计算的基础。探寻双重介质渗流模型的实空间求解方法是解决此类渗流问题、完善双重介质渗流理论的最佳途径。本文针对常规双重介质油气藏和页岩气藏,采用体积源方法研究非稳态渗流问题。综合应用渗流力学、油藏工程、偏微分方程、数值计算、计算机程序设计等知识,以建立双重介质非稳态渗流模型为起点,推导相应的体积源函数,并阐述在不同类型的井的生产动态分析中的应用,最后将论文主要理论算法程序化。主要取得如下成果:(1)从常规双重介质油气藏、页岩气藏基本渗流原理出发,采用体积源方法建立三维空间非稳态渗流模型;采用积分变换法进行求解,分别求取实空间和Laplace空间的体积源函数,并分析不同空间中体积源函数的应用范围。(2)针对不同假设(均匀流量假设、无限导流假设、有限导流假设)下不同类型的井(直井、垂直裂缝井、水平井、分段压裂水平井),根据体积源函数,结合叠加原理和源内流动压降模型建立相应的压力动态模型,并与传统理论模型的结果进行比较,验证双重介质体积源函数的有效性,展示体积源方法相比于传统方法的优点,并分析各参数对压力动态的影响。(3)针对裂缝性油气藏,建立考虑水平井管流压降、人工裂缝内高速非达西流动压降的半解析产能评价模型;分析人工裂缝参数间的相互关系,并依此提出新的裂缝参数优化设计方法。(4)基于双重介质体积源渗流模型,采用Visual Basic 6.0编制分段压裂水平井产能评价软件,应用于均质/双重介质油气藏分段压裂压前参数优化及压后产能评价之中。通过研究表明,体积源方法可良好地应用于研究双重介质中线性和非线性渗流问题,并且继承了在均质储层中应用时的优点:函数性质优良、计算步骤简便、基本源函数适应性更好、在结构更为复杂的井中应用时效率更高。论文的研究对裂缝性储层、非常规储层的开发有积极的指导意义。
[Abstract]:The dual medium is used to describe the reservoir where the natural fracture develops or the fracture network is formed after volume fracturing. Its percolation theory is widely used in well test analysis, productivity evaluation and reservoir fracture prediction. Domestic and foreign scholars have made a lot of research achievements on the theory and application of dual medium seepage, but they mainly focus on the percolation problems of vertical fractured wells, horizontal wells, vertical fractured wells, and horizontal wells. However, the research on the horizontal well of fracturing is less, and the research on the seepage problem of shale gas reservoir needs to be further deepened. The solution of the seepage problem of dual medium is usually based on Laplace transform and combined with the corresponding numerical inversion method. It can be well applied to solve the problem of isoseepage in variable flow rate production. However, when the pressure and flow rate of high speed non-Darcy flow are nonlinear, the problem can not be transformed by Laplace, considering the pipe flow in horizontal well, and the non-Darcy flow at high speed. This kind of seepage problem has become an intractable problem in the traditional double medium seepage theory. The semi-analytical solution method for this kind of nonlinear seepage problem in real space is very mature, and the flow rate in each time period is mainly solved by discrete time. It can be seen that the basic solution in real space is the basis of this kind of semi-analytical method. The best way to perfect the theory of dual medium percolation. In this paper, the volume source method is used to study the problem of unsteady flow in conventional dual medium reservoirs and shale gas reservoirs. Comprehensive application of percolation mechanics, reservoir engineering, partial differential equation, numerical calculation, Based on the knowledge of computer programming, the volume source function is derived from the establishment of a dual medium unsteady flow model, and its application in the production dynamic analysis of different types of wells is expounded. Finally, the main theoretical algorithms are programmed. The main achievements are as follows: 1) based on the basic percolation principle of conventional dual medium reservoir and shale gas reservoir, the volume source method is used to establish the three-dimensional spatial unsteady seepage model. The volume source functions of real space and Laplace space are obtained by using integral transformation method, and the range of application of volume source function in different space is analyzed. Different types of wells (vertical well, vertical fracture well, horizontal well, segmented fracturing horizontal well) under the finite diversion hypothesis, according to volume source function, combined with the superposition principle and the flow pressure drop model in the source, the corresponding pressure dynamic model is established. Compared with the results of the traditional theoretical model, the validity of the volume source function of the dual medium is verified, the advantages of the volume source method compared with the traditional method are demonstrated, and the influence of various parameters on the pressure performance is analyzed. A semi-analytical productivity evaluation model considering pipe pressure drop and non-Darcy flow pressure drop in artificial fractures is established, and the relationship between parameters of artificial fractures is analyzed. Based on the dual medium volume source seepage model and Visual Basic 6.0, a new fracture parameter optimization design method, I. e., the productivity evaluation software for horizontal well fracturing is presented. It is applied to the optimization of parameters before fracturing and the evaluation of productivity after fracturing in homogeneous / double heavy medium reservoirs. The results show that the volume source method can be applied to the study of linear and nonlinear percolation problems in dual media. And inherited the advantages of application in homogeneous reservoir: good function property, simple calculation procedure, better adaptability of basic source function, and higher efficiency when applied in wells with more complicated structure. The development of unconventional reservoir has positive guiding significance.
【学位授予单位】：西南石油大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TE312

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