应力敏感性油藏油水两相渗流数值模拟

Numerical Simulation of Oil and Water Tow-Phase See-page in Stress Sensitivity Reservoirs

本文给出了应力敏感性介质油水两相渗流的数学模型,并采用有限差分方法进行求解。计算过程中,每个时间步的渗透率根据实验测得的无因次渗透率与有效应力关系曲线求得,根据新的渗透率分布求解下一时间步的压力分布。通过数值模拟方法分别研究了不存在应力敏感性、以及三种不同敏感程度的算例,并给出无因次渗透率的空间分布图、日产油量以及平均地层压力的对比曲线图。结果表明:应力敏感性越强,平均地层压力的变化范围越小,无水采油期内的日产油量越低;应力敏感性越弱,平均地层压力的变化范围越大,无水采油期内的日产油量越高。在生产井和注水井附近,渗透率分布变化较为急剧,远离井的区域变化较为平缓。

The mathematical model of oil and water two-phase seepage was derived and solved by numerical limited difference method in the paper. During the simulation, permeability values of every time step were calculated by relation curves between dimensionless permeability and effective stress obtained by experiment. Then the pressure distribution of next time step was calculated by the new permeability distribution. The situation of non-stress sensitivity and three different kinds of sensitive degree are studied respectively through numerical stimulation method. Figures of the dimensionless permeability space distribution, the daily oil production and the average reservoir pressure were drawn. Results show the stronger the stress sensitivity is, the variation range of the average reservoir pressure is small and the daily oil production is lower during the water free oil production period. While the weaker the stress sensitivity is, the variation range of the average reservoir pressure is large and the daily oil production is higher during the water free oil production period. Permeability distribution changes sharply around production and injection wells, while smoothly far from wells.