【作者】 王殿生；

【导师】 姚军；

【作者基本信息】 中国石油大学 ， 油气田开发工程， 2009， 博士

【摘要】 碳酸盐岩缝洞型油藏存在着孔、缝和洞,且结构复杂多样,尺度大小分布范围非常大,具有较大的各向异性和非均质性,导致流体在缝洞型介质中的流动复杂。开展缝洞型介质流动机理的研究,对于此类油藏的高效开发具有重要意义。论文以物理模拟实验为主,结合理论分析和数值模拟,开展了缝洞型介质流动机理的研究。首先,根据物理模拟的相似理论推导了缝洞型介质物理模拟的相似准则数群,结合缝洞型介质的特征,确定了物理意义明确、简单实用的7个主要相似准则;针对基质岩块储渗能力极弱的特点,提出了重点考虑简单且主要因素的概念化模型设计思想,开发了缝洞规格和结构的精确控制技术,以大理石为模型材料设计制作了不同缝洞结构的物理模型38个。采用传感器测量技术和计算机数据自动控制和采集技术,建立了物理模型实验装置和实验系统,开发了实验控制和数据测量处理系统软件,实现了压力、注入流量、产出液流量(质量流量和体积流量)、产出液总量(质量和体积)、产出液密度、产出液温度等实验数据的实时测量、采集、存储和处理。形成了一套缝洞型介质流动实验的方法和技术,为开展单相和两相流动的物理模型实验奠定了基础。其次,通过单相流动实验的结果分析,建立了缝洞型介质渗透率与缝密度、缝张开度、缝粗糙度、缝连通度、洞隙度、空隙度、介质厚度等7个参数相关的拟合公式,发现了缝系统是影响渗透率的主要因素,洞系统的影响一般不会使渗透率增加一倍;揭示了缝与缝之间以及缝与洞之间的结构关系对线性流动转变为非线性流动的临界速度的影响机制;建立了缝洞型介质线性流动达西方程,非线性流动二项式方程、指数式方程以及雷诺数方程。第三,根据两相流动实验结果,分析了缝洞型介质结构与油水相对渗透率曲线特征、水驱油效率和含水率变化规律的相关关系:水相相对渗透率曲线一般呈下凹型,单裂缝且张开度大于100μm时可呈直线。裂缝张开度越小,网络结构越复杂,随着含水饱和度的增大水相相对渗透率增加越缓慢;缝洞网络结构复杂,水驱油效率低,而结构复杂性对水驱油效率的影响程度随洞隙度的增大而减小。缝洞网络结构复杂,无水采出程度高;但见水后含水率上升快,最终采出程度低。最后,建立了缝洞型介质单相线性流动和非线性流动以及两相流动的有限元数值模拟方法,通过对典型物理模型实验的数值模拟分析,验证了数值模拟方法的可靠性;通过数值模拟方法,研究了缝洞型介质中压力、速度、饱和度的变化规律,揭示了各因素的影响机制,即洞的存在是影响流动规律的重要因素,重力对洞中水驱油有重要影响。论文研究成果为缝洞型油藏的试井解释、油藏数值模拟、开发决策等奠定了坚实的基础,具有广阔的应用价值。更多还原

【Abstract】 Fractured-vuggy carbonate reservoir with matrix, fracture and vug is well known as extremely anisotropy and heterogeneity, where pore structure is complex and pore size has a large scale. Therefore the fluid flow in fractured-vuggy carbonate reservoir has special properties. Study on fluid flow mechanism in fractured-vuggy porous media has important signification to optimization of oil recovery from such reservoirs. In this dissertation, physical modeling experiment study attaching theoretical analysis and numerical simulation on fluid flow in the artificial fractured-vuggy is presented.First, a group of similarity criterion of physical simulation was derived based on the similarity theory of physical modeling, and simple and practical seven main similarity criterions with specific physical meaning were defined on considering characteristics of fractured-vuggy porous media.The design method of conceptual model considering the simple but concernful factors was put forward according to the property that fluid is almost incapable of permeating and storing in matrix of many fractured-vuggy carbonate reservoirs. Thirty-eight models with different fracture-vug structures were made from marble materials through the self-developed technique of controlling accurately size and configuration of fracture and vug. A set of experimental apparatus for physical modeling experiment was built being equipped with sensor measuring technique and computer automatic control and data acquisition technique. A systems software offering experimental control and data measurement and processing was developed, in which the real-time measuring, acquirement, memory and processing of data were implemented, which include pressure, injection and output flow rate, accumulated mass and volume production, and density and temperature of produced fluid. On account of the experimental process of fluid flow in porous media and on the basic of much experimental practice, a suit of experimental methods and techniques for fluid flow in the fractured-vuggy media was generated, and the physical modeling experiments of one- and two-phase fluid flow were systemically carried out as following.The next, by the experimental results analysis of single phase flow, an empirical formula between permeability of fractured-vuggy media and seven parameters, including fracture density, fracture aperture, fracture roughness, fracture connectivity, vug porosity, porosity and media thickness, were fitted. The results indicate that fracture system is the main factor affecting on permeability and vug system generally wouldn’t make the permeability double. At the same time, the effects on the critical velocity of linear and non-linear flow between fracture and fracture, fracture and vug, were respectively analyzed, and the Darcy equation of linear flow and binomial equation, exponential equation and Reynolds equation of non-linear flow were given.Third, the relationships between structure of fractured-vuggy media and the characteristics of oil-water relative permeability curve, water-oil displacement efficiency and water cut variation was respectively analyzed by the experimental results of two-phase flow. Relative permeability curve of water generally shows down concave and it will also show line when the aperture of single fracture is greater than 100μm. The smaller is the fracture aperture and more complex is the net structure, the slower increases the relative permeability of water with water saturation. Water-oil displacement efficiency is low when fractured-vuggy networks are complex, but the structure complexity has smaller effects on the water-oil displacement efficiency with vug porosity increasing. Water-free oil production is high when fractured-vuggy networks are complex, but water cut rises quickly after water breakthrough resulting in low ultimate recovery.The last, the finite element method (FEM) for numerical simulation of linear and non-linear flow of single phase fluid and two-phase flow in fractured-vuggy media were constructed. By the numerical simulation to the typical physical model experiment, it is verified that the developing numerical simulation method is reliable. The variations of pressure, velocity and water saturation in fractured-vuggy media were simulated by FEM,on which influences of correlative parameters were discussed. The results suggest that the existing of vug affects seriously flow law, and gravity has impotent effect on water-oil displacement in vug.The research results lay a solid foundation for well test interpretation, reservoir numerical simulation and development decision of fractured-vuggy reservoirs, and have broad practice value.更多还原