水驱稠油非线性渗流数值模拟研究与应用

发布时间：2018-03-21 02:26

本文选题：稠油油藏　切入点：非线性渗流　出处：《长江大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着常规原油储量的逐渐减少,稠油资源越来越受到人们的重视。目前稠油开采规模的逐步扩大,人们对它的研究也越来越多,国家已将部分稠油油藏列为重点开发项目,稠油丌采将日益显示出重要的战略地位。但稠油由于其自身的特点,在地下渗流时表现出与常规原油不同的渗流特征,它对油藏的开发、工艺技术的选择及开发指标等都有影响,所以正确认识稠油的渗流规律是有效开发稠油油藏的必要条件。稠油是一种复杂的、多组分的有机混合物,由于稠油是由一系列较大分子组成、存在某种形式的超分子结构,这使得稠油具有高粘度、高密度以及非牛顿流体的特点。稠油的非牛顿流体特点主要体现在其具有启动压力梯度,即当驱替压力梯度小于启动压力梯度时稠油不流动,当驱替压力梯度大于启动压力梯度后稠油按拟线性渗流段流动。稠油的启动压力梯度目前主要从多孔介质孔道的复杂性、流体的非牛顿性、流体边界层性质异常进行解释。大量实践证明,达西规律所描述的仅仅是整个渗流过程的一小部分,许多渗流过程都不符合达西定律,通常将这些渗流称为非牛顿、非线性流体渗流。非线性渗流大致包括以下几种：(1)非牛顿流体渗流,这时流体粘度为剪切速率的函数；(2)高速下的非线性紊流,这时惯性力作用不可忽视,紊流附加阻力对流动产生明显影响；(3)变形多孔介质渗流,这时多孔介质渗流参数为渗流条件的函数；(4)非等温渗流；(5)低速渗流,这时多孔介质物性参数为渗流条件的函数。对于水驱稠油油藏,就是一个典型的非线性渗流的例子。目前,数值模拟技术已成为人们认识和描述油气藏开发生产规律的有力工具。但非牛顿流体非线性渗流的数值模拟研究尚处于初级阶段,截止目前,国内外尚无比较系统的方法、技术和模拟系统。目前关于非线性渗流的研究大多数都是针对单相流,形成共识的有如下三个方面：(1)原油性质对渗流的影响：在稠油油藏中,原油粘度很高,使原油呈现非牛顿流体特性,主要表现为粘弹性或拟塑性；(2)介质的渗透性对渗流的影响：介质与流体相互作用,严重阻碍流体流动,使流体渗流具有启动压力梯度；(3)介质的非弹性：在开发过程中,储层孔隙度与渗透率随地层压力变化而变化,并且这个过程往往是不可逆的。这三个方面都会使原油在油藏中的渗流呈现非线性流。本文首先对稠油启动压力梯度形成机理、启动压力梯度的研究历程、稠油启动压力梯度测量方法、非线性渗流数学模型与数值模拟方法研究现状等方面进行广泛调研。然后依据SZ36-1油田与QHD32-6油田原油的非线性渗流实验规律,从渗流曲线形态、启动压力梯度形成机理、流度与启动压力梯度关系这3方面考虑,建立了变启动压力梯度的运动方程。随后详细推导了变启动压力梯度下的数学模型,用MPES方法建立其数值模型,并编制了非线性渗流模拟器。通过大量测试在保证模拟器可靠的前提下,应用非线性渗流模拟器对反5点、反9点机理模型与QHD32-6油田典型井组模型进行了非线性渗流计算。模拟结果表明,启动压力梯度对油田开发产生了3个方面的影响：(A)加快最小渗流阻力通道的形成,此后注入水便会大部分或全部的沿该通道前进,使波及范围大大减少；(B)加剧水油流度差异与指进现象,致使非活塞现象愈加严重,驱油效率大大降低；(C)加剧层间渗流阻力差异与层间矛盾。通过对这些规律的深入挖掘,将为稠油水驱的合理开发提供理论与技术支撑。
[Abstract]:With dwindling reserves of conventional crude oil, heavy oil resources has attracted more and more attention. At present, the scale of heavy oil production gradually expanded, and the studies of it are more and more countries have been part of heavy oil reservoir as a key development project, will increasingly shows the strategic importance of heavy oil exploitation of heavy oil. But because of its own characteristics the show features different from conventional crude oil seepage in underground seepage, the development of the reservoir, have effect on technology selection and development index, so the correct understanding of the seepage law of heavy oil is a necessary condition for effective development of heavy oil reservoir. The heavy oil is a complex mixture of organic groups, because of heavy oil, is composed of a series of larger molecules, supramolecular structure exist in some form, which makes the heavy oil with high viscosity, high density and characteristics of non Newtonian fluid. Non Newtonian viscous flow Body characteristics are mainly reflected in its starting pressure gradient, i.e. when the displacement pressure gradient is smaller than the heavy oil does not flow starting pressure gradient, when the displacement pressure gradient is greater than the threshold pressure gradient after heavy oil according to the quasi linear seepage flow. The starting pressure gradient of heavy oil is mainly from the complexity of porous medium pore, non Newtonian fluid. The nature of the fluid boundary layer anomaly was explained. It proved that the Darcy's law described is only a small part of the entire seepage process, many seepage process does not meet the Darcy's law, are called non Newtonian flow, nonlinear fluid flow. The nonlinear flow generally include the following: (1) non Newtonian fluid flow. When the viscosity of the fluid as a function of shear rate; (2) nonlinear turbulence at high speed, the inertia force can not be ignored, the turbulent flow of additional resistance significantly affect production; (3) the deformation of porous media seepage, then the function parameters of porous media seepage for seepage conditions; (4) the non isothermal seepage; (5) low speed flow, then the function of physical properties of porous media seepage conditions. For water flooding in heavy oil reservoir is a typical nonlinear seepage flow numerical example. At present, the simulation technology has become a powerful tool for people to understand and describe the reservoir development and production rules. But the non Newton fluid numerical simulation study of nonlinear seepage is still in the initial stage, up to now, there is no systematic method, technology and simulation system. The current research on nonlinear flow mostly for single-phase flow, three the following aspects of consensus: (1) effects of crude oil properties on seepage in heavy oil reservoir, crude oil viscosity is very high, the crude oil showed non Newton fluid characteristics, mainly for viscoelastic or quasi plastic ; (2) influence the permeability of the medium to flow interaction medium and fluid, hinder fluid flow, the fluid flow with starting pressure gradient; (3) non elastic medium: in the process of development, the reservoir porosity and permeability of formation pressure changes, and this process is often irreversible. These three aspects will make the oil seepage in the reservoir. This paper presents the nonlinear flow of heavy oil starting pressure gradient formation mechanism, start the research course of pressure gradient, heavy starting pressure gradient measurement method, nonlinear seepage flow mathematical model and numerical simulation method to study the status quo and other aspects of extensive investigation. Then according to the nonlinear seepage the experiment of crude oil SZ36-1 and QHD32-6 oilfield, from the seepage curve, the starting pressure gradient formation mechanism, the 3 aspects of the relationship between flow and starting pressure gradient, the establishment of The change of starting pressure gradient equations of motion are derived in detail. Then the mathematical model of variable threshold pressure gradient, the numerical model established by MPES method, and the nonlinear flow simulator. Through a lot of tests under the premise of ensuring reliable simulator under the application of nonlinear seepage simulator against 5 points, 9 points against the mechanism model and QHD32-6 in a typical well group model of nonlinear seepage calculation. The simulation results show that the starting pressure gradient has 3 Effects on oil field development: (A) to accelerate the formation of minimum flow resistance channel, then injected water will most or all along the path, the scope is greatly reduced; (B) increased water oil mobility differences and fingering phenomenon, resulting in more and more non piston phenomenon is serious, the oil displacement efficiency is greatly reduced; (C) difference between flow resistance between layers increased and interlayer. Based on these rules. The deep excavation will provide theoretical and technical support for the rational development of heavy oil water flooding.

【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE312

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