【摘要】 搞清地层流体物理性质是科学管理油藏的重要前提,注气开发也不例外。基于简化实际气驱过程的"三步近似法"、物质平衡原理和相态基本原理等概念,将"差异化运移"和"加速凝析加积"两种气驱"油墙"形成机制与挥发油藏和凝析气藏开发实际经验和相态实验评价方法相结合,首次得到见气见效阶段"油墙"的溶解气油比、泡点压力、密度、地下黏度和体积系数等关键物性参数计算方法。用于国内多个二氧化碳驱开发试验项目呈现了很好的适应性,发现混相/近混相CO₂驱"油墙"泡点压力比原状地层油的泡点压力约高4.0⁶.0 MPa,溶解气油比要比地层原油升高40⁶0 m³/m³;为注气开发油藏见气见效后油墙集中采出阶段生产井工作制度确定和采油工艺优化提供了主要理论依据。更多还原

【Abstract】 It is an important prerequisite for the scientific reservoir management to acquire physical properties of formation fluids. Gas flooding is no exception. Two mechanism forming gas flooding " oil bank" including" differentiation in migration of crude oil components’ and" accelerated accretion of condensation near gas flooding frontier"are described in detail,during which four steps of " oil bank" forming are indentified. The concept of " light liquid forming oil bank（ LLFOB） " is introduced through the analysis of complex phase change of the injection gas and formation oil mixture. It is discovered that LLFOB contribute to the difference physical properties between gas flooding" oil bank" and formation crude oil because the composition of LLFOB is between volatile oil and saturation condensate. Based on the " three-step approximation" method to simplify real gas flooding process,material balance principle,and basic principle of phase behavior,these two gas flooding " oil bank" forming mechanism,experience of volatile oil reservoir development and condensate gas reservoir development,and the new concept of LLFOB,experimental method of phase behavior evaluation are combined to form the systematic prediction procedure and calculation methods of key physical parameters of " oil bank",including dissolved gas oil ratio,bubble point pressure,underground density,surface density,viscosity and volume factor of " oil bank" for the first time. These methods present sound adaptability when applied to several carbon dioxide flooding projects. It is discovered theoretically that the bubble point pressure and the dissolved gas oil ratio of " oil bank" formed during miscible or near miscible CO₂ flooding process will rise by 4. 0 6. 0 MPa and 40 60 m³/ m³ respectively. However,viscosity of " oil bank"will always decrease by about thirty percent compared to original oil viscosity. These above research results provide the main theoretical basis for the determination of working system and the optimization of production technology during early gas emergence period or the centralized recovery stage of " oil bank" in gas flooding low permeable reservoirs.更多还原