特低渗透油藏启动压力梯度研究

针对单相和油水两相流体启动压力梯度的产生机理和对渗流规律的影响问题,通过稳态"压差-流量"测定启动压力梯度法,分别用模拟油、地层水、注入水和蒸馏水对我国某油田119块典型特低渗岩芯进行驱替实验,得到了单相和油水两相渗流的启动压力梯度值,分析了启动压力梯度的变化规律.物理模拟和理论研究都表明,不同渗流介质测得的启动压力梯度与渗透率均成幂函数关系,并且幂指数近似为-1.同时,由于毛管力和贾敏效应作用,油水两相启动压力梯度远远大于单相渗流的启动压力梯度.结合油田实际,说明了启动压力梯度在特低渗透油气藏开发中的应用.

STUDY ON THRESHOLD PRESSURE GRADIENT IN ULTRA-LOW PERMEABILITY RESERVOIR

Aimed at the forming mechanism of the single phase and oil-water two phases threshold pressure gradient (TPG) and the influence on the law of flow through porous media, displacing experiment is done to the typical cores with ultra-low permeability from block 119 at a certain oilfield with simulated oil, formation water and injected water respectively through the method of stable "pressure difference-flow capacity" measuring TPG, and the TPG value of single phase and oil-water two phases flow through porous media, the changing law of TPG is analyzed. Both physical simulation and theoriodical research indicate that the relationship between TPG measured with eifferent media and permeability is power function, and the exponent sign is close to -1. Meanwhile, oil water two phases TPG is much greater than single phase one because of capillary force and Jiamin effect. Finally, the application of TPG in ultra-low permeability reservoir exploitation is described.