【作者】 熊伟；

【导师】 雷群；

【作者基本信息】 中国科学院研究生院（渗流流体力学研究所） ， 流体力学， 2011， 博士

【摘要】 本文的研究针对低渗透油藏有效开发面临的三个主要基础问题：一是不同油区气测渗透率相近的低渗透油藏储量动用难度、开发效果差异大,现有的分类评价方法不能体现低渗透油藏储层特征,不能有效的对低渗透储量进行分类评价,指导低渗透储量合理、有序开发。二是低渗透油藏渗流基础理论。随着开采对象的渗透率越来越低,渗流的非线性程度越来越强,以启动压力梯度为核心的非达西渗流不能描述低渗透油藏渗流的弯曲段,而这个弯曲段恰好是低渗透油藏的主要渗流区间,因此有必要对低渗透油藏的渗流理论进行深层次的探索,建立低渗透油藏开发的数值模拟方法,形成低渗透油藏开发指标计算技术。三是低渗透油藏的井网优化原则没有考虑建立有效驱动压力系统,使得在开发时难以达到方案设计的产量,而且产量递减快,大大降低了低渗透油藏开发水平和效果。以建立有效驱动为核心的井网优化方法是低渗透油藏有效开发的重要基础理论。以恒速压汞、核磁共振和渗流实验等手段为基础,深入研究和分析不同油区低渗透油藏孔隙结构、固液作用和渗流特征变化规律,提出了低渗透油藏渗流能力和开发潜力评价的新参数即主流喉道半径、可动流体饱和度、启动压力梯度、粘土含量及类型和原油粘度五个参数,并给出了分级评价的参数界限。利用模糊数学方法,建立了低渗透油藏分级评价方法,编制了分级评价软件,形成了分类评价技术。在长庆、大庆、新疆等油田的应用效果较好,特别是长庆油田的产量特征与储层分类吻合程度很高,表明以体现低渗透油藏储层特征的参数形成的评价参数体系和方法是科学和合理的。毛细管实验和岩心实验表明微细孔隙和喉道影响流体的渗流,在低速段由于固液作用,边界层的厚度随着驱动压力梯度的增大而减小以及微观上流体在不同大小喉道之间的选择性流动是非线性渗流的两个主要机理。在宏观上表现为储层的水测渗透率不再是常数,而是随驱动压力梯度增加而增大的函数。在大量的实验数据基础上,建立了低渗透油藏非线性渗流的运动方程。结合现有的大型数值模拟程序,将非线性项线性化,编制了非线性渗流数值模拟软件,形成了非线性渗流数值模拟技术。以物理模拟实验为基础,分析了油田开发指标参数与有效驱动的关系,提出了低渗透油藏有效驱动压力系统的概念即能够维持预期产量的压力系统。影响驱动有效性的主要因素有油藏物性(渗透率、厚度、原油粘度)、井网、井距、人工压裂缝长、超前注水的压力等七个因素。建立有效驱动压力系统的井网优化方法即如何针对给定的油藏协调井网、井距、排距、压裂缝长和超前注水压力以达到并保持预期产量。以长庆超低渗透油藏白153井区为例,评价了矩形井网和菱形反九点的开发效果,发现在现行的两种井网下都没有建立有效驱动,达不到2t/d为预期产量。通过井网、井距和排距优化,480×200m的五点井网可以实现有效驱动,单井产量达到2t/d。而菱形反九点井网只能实现1.5t/d的产量,井距和排距为480×130m。更多还原

【Abstract】 This paper studies on basic theories on three main issues to effective development of low permeability reservoirs: first, the developement difficulty and effects of low permeability reservoirs with similar air permeability is very different, and the existing reservoir classification and evaluation method can not reflect the characteristics of low permeability reservoirs. So, it’s hard to guide rational and orderly development of it. Second, the basic theory of flow in low permeability reservoir is unclear. With the permeability of reservoir more lower, nonlinear flow becomes more strongly. Conventional non-Darcy flow model can not describe the nonlinear phenomenon. It is essential to study the flow theory of low permeability reservoir to establish numerical simulation and calculation method of development indicators. The optimization principle of low permeability reservoir is not well considering the effective driving pressure system, making it difficult to achieve in the development designing, and production declines rapidly. This makes the development level of the low permeability reservoir greatly low. To establish well optimization based on effective drivens is an important basis for effective development theory of low permeability reservoirs.By controlled mercury, NMR and seepage experiments, pore structure, solid-liquid interaction and flow characteristics of different areas of low permeability reservoir is studied. Five new parameters of reservoir evaluation are proposed, including main throat radius, movable fluid saturation, threshold pressure gradient, clay content and type, and oil viscosity. Fuzzy optimization method is used to form reservoir evaluation techniques and generate reservoir evaluation software. This technique is used in Changqing, Daqing and Xinjiang Oilfield. Results show that it is valid to evaluate low perservoirs, especially the Changqing oilfield.Capillary experiments and seepage experiments results show that tiny pore and throat effects seepage. The decreasing of the thickness of solid-liquid boundary layer as the driving pressure gradient increasing and the selective flow of the fluid in the throat with different size is the two main mechanisms of non-linear flow in the low permeability reservoir. So, the water permeability is no longer constant, but the function of driving pressure gradient. A new nonlinear flow equation of motion is proposed based on a large number of experimental data. Combined with existing large-scale numerical simulation program, new numerical simulation software considering nonlinear flow is developed.The relationship between the relevant development indicators and effective driven is analysed. The concept of the effective driving pressure system, the pressure system to maintain the expected production, is propesed. The main factors effecting effective driving system is the reservoir properties (permeability, thickness and oil viscosity), well pattern, well spacing, fracture length of manual crack and the pressure of intput water ahead. Establishment of an effective driving pressure system has to optimize these parameters to achieve expected production for a given yield.The development effect of the rectangular and diamond well pattern is evaluated in Bai 153 tight reservoirs in Changqing field. Results show that effective driving is not archeived under these two well patterns, failing the expected production 2t/d. Through the optimization, it’s found that five points pattern with 480x200m can be achieved effectively driven system, single well production 2t/d. While the inversed nine point pattern with 480×130m can only be achieved production 1.5t/d.更多还原