低渗透油气藏压裂水平井分形渗流理论研究

发布时间：2018-02-09 17:09

本文关键词： 低渗透油气藏多段压裂水平井分形理论树状分形网络　出处：《西南石油大学》2015年博士论文　论文类型：学位论文

【摘要】：低渗透油气资源作为世界油气生产的重要组成部分,在相当长时期内有望充当非常规油气资源开发的“领头羊”。但由于低渗透油气藏特殊的地质特征与渗流机理,相比常规油气藏,其储量丰度小,产量递减快,最终使得开发难度大,技术要求高。因此对低渗透油气藏地质特征、渗流机理以及油气井产能的研究变得至关重要。本文在充分调研多段压裂水平井产能的基础上,结合低渗透油气藏基本地质特征,引入统一毛细管束描述低渗透油气藏基质,考虑基质内多尺度流动与应力敏感效应,并讨论了启动压力梯度现象；引入树状分形裂缝网络模拟水力压裂裂缝网络,建立了树状分形裂缝网络的生成方法与裂缝、节点编号规则,分析了树状分形裂缝网络的流动特征,建立了多段压裂水平井裂缝网络流动模型；运用单裂缝势函数及势的叠加原理建立了多段压裂水平井裂缝网络渗流模型,结合多段压裂水平井裂缝网络流动模型,建立了多段压裂水平井基质、裂缝耦合流动模型及产能预测模型,最后运用实例数据验证了产能模型的准确性,并对影响多段压裂水平井产能的因素进行了分析,得出了各因素对多段压裂水平井产能影响的程度。主要成果和认识如下：(1)针对油气藏储层的复杂性,基于毛细管渗流基本原理,建立了多孔介质统一毛细管束模型,该模型引入了毛细管流量函数,毛细管长度函数,毛细管概率密度分布函数。通过对比传统毛细管束模型,多孔介质统一毛细管束模型能够较好的总结前人研究成果。通过对比实验测量数据,多孔介质统一毛细管束模型的正确性与实用性得到了验证。(2)基于低渗透油气藏基质的实际情况,运用多孔介质统一毛细管束模型,从微观毛细管流动模型出发,分别对低渗透油气藏储层多尺度流动、应力敏感效应进行了解释,并讨论了启动压力梯度现象,该模型能更多地揭示多孔介质内的流体流动机理。(3)基于树状分形裂缝网络物理模型,通过明确树状分形裂缝网络的基本参数与基本参数约束条件,确定了树状分形裂缝网络的生成及编号规则。基于多段压裂水平井裂缝网络由多支树状分形裂缝网络的假设,实例生成了多段压裂水平井裂缝网络。通过单条裂缝流动特征与考虑多尺度流动的单条裂缝流动特征,结合树状分形裂缝网络特殊结构,分析了树状分形裂缝网络流动特征。(4)研究单裂缝的地层势分布,将单裂缝视为三维线汇,推导出了单裂缝在无界地层中稳定生产时的势分布规律。在此基础上,根据镜像反映和叠加原理,推导出了几种常见油气藏中单裂缝生产时的势分布规律,由此得到地层中的压力分布规律。基于多段压裂水平井的树状分形裂缝网络由多支树状分形裂缝网络组成的假设,建立了多段压裂水平井产能计算的半解析模型,通过对多段压裂水平井油气藏渗流势分布的研究,得到了多段压裂水平井裂缝网络单裂缝的势分布函数,结合多段压裂水平井裂缝网络流动特征,考虑到油气藏渗流和裂缝网络的相互影响,将两者耦合联立求解,利用半解析耦合算法,求得了多段压裂水平井产能及裂缝网络压力分布。
[Abstract]:Low permeability oil and gas resources as an important part of the world oil and gas production, in a quite long period of time is expected to serve as the development of unconventional oil and gas resources of the "leader". But because of the geological characteristics and seepage mechanism of low permeability reservoir is special, compared to conventional oil and gas reservoirs, the abundance of small, fast decline, the development is difficult, high technical requirements. So the reservoir geological characteristics of low permeability oil and gas seepage mechanism and research of oil and gas well productivity becomes very important. Based on the full investigation of multi fracturing horizontal well productivity, combined with low permeability oil and gas reservoir geological characteristics, the introduction of a unified description of the matrix of low permeability oil capillary bundle gas reservoir, considering the multi scale flow matrix and stress sensitive effect, and discussed the starting pressure gradient; the introduction of Fractal Simulation of hydraulic fracturing fracture network tree network, a fractal tree splitting Crack and crack generation method of the network, node numbering rules, analysis of flow characteristics of the fractal crack network tree, a multi segment fracture network fracturing horizontal well flow model; using the principle of superposition function of single crack potential and the potential is established fractured horizontal well fracture network seepage flow model with multi segment fracture network of horizontal wells fracturing flow model, established multi fractured horizontal well matrix fracture coupling prediction model and flow capacity model, finally verified the accuracy of capacity model using instance data, and the influence factors of multi fracturing horizontal well productivity were analyzed, the influence of various factors on multi fracturing horizontal well productivity level. The results are as follows: (1) aiming at complex oil and gas reservoirs, based on the basic principle of capillary flow, the establishment of a unified capillary model of porous media, the model introduces the hair Capillary flow function, capillary capillary length function, probability density distribution function. By comparing the traditional capillary model of porous media, unified capillary bundle model to summarize previous research results better. By comparing the experimental data. The correctness of the porous medium capillary bundle model unified and practicability has been verified. (2) the actual situation of low matrix permeability oil and gas reservoirs based on the use of a unified capillary model of porous media, starting from the micro capillary flow model, respectively for the low permeability reservoir multi-scale flow, stress sensitive effect is explained, and discussed the starting pressure gradient, this model can reveal the mechanism of fluid flow in porous media. (3) fractal crack network based on physical model, through the basic parameters of clear tree fractal fracture network and basic parameter constraints, determine the tree Generation and number of fractal fracture network. Multi fracturing horizontal well fracture network is composed of multi branch tree fractal crack network based on the assumption that the examples generated multi fracturing horizontal well fracture network. With the consideration of flow characteristics of single crack in single crack flow multi-scale flow characteristics, combined with the special structure of the fractal crack network tree analysis. The flow characteristics of the fractal crack network tree. (4) potential distribution of single crack formation, single crack as a 3D line sink, potential distribution is derived for single crack stable production of borehole in time. On this basis, according to the mirror reflection and superposition principle, deduced the potential distribution in the the production of several common single fracture reservoirs, the pressure distribution in the strata. Based on the fractal crack network multi fracturing horizontal well by multi branch tree fractal crack network a That established a semi analytical model to calculate multi fracturing horizontal well productivity, the permeability distribution of potential of multi fractured horizontal well reservoir, the potential distribution function of multi fracturing horizontal well fracture network of single crack, combined with the flow characteristics of multi segment fracture network fracturing horizontal well, considering the mutual influence of oil gas seepage and fracture network, the two coupled simultaneous solution, using semi analytical coupled algorithm, obtained the multi-stage fracturing horizontal well deliverability and fracture pressure distribution network.

【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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