水驱厚层油藏纵向波及系数预测新模型

A New Vertical Sweep Efficiency Prediction Model for Water-Flooding Thick Oil Reservoirs

针对厚油层内部的强非均质性和窜流现象导致的纵向波及系数预测精度低的问题,考虑层内受瞬时窜流及渗透率非均质性的影响,引入渗透率对数正态分布函数,结合拟相对渗透率法和水驱油理论,建立了纵向波及系数预测新模型。研究结果表明:模型计算结果与矿场实际数据基本吻合,从而验证了模型的可靠性和较高的精确度;敏感性分析表明,渗透率变异系数和流度比越大的油层,纵向波及系数越小,原油主要在高含水时期被采出,此时需调整注采井网,合理划分层系,从而提高油藏纵向波及系数。研究成果为水驱开发厚层油藏纵向波及系数的预测提供了理论指导。

The strong heterogeneity and channeling inside thick oil layers can deteriorate the prediction accuracy of vertical sweep efficiency. To solve this problem, the logarithmic normal distribution function of permeability was in- troduced to analyze the effect of instantaneous channeling and permeability heterogeneity in the layers. Then, a new vertical sweep efficiency prediction model was built up according to pseudo relative permeability method and water flooding theory. It is indicated that the calculation results of this new model is basically in agreement with the actual data. It is verified that this new model is reliable with higher accuracy. Sensitivity analysis indicates that the oil lay- er with higher the permeability variation coefficient and mobility ratio has lower vertical sweep efficiency, and its crude oil is mostly produced at high water cut stage. At this stage, it is necessary to adjust injection/production well patterns and divide series of strata rationally so as to improve the vertical sweep efficiency of oil reservoirs. The re- search results can be used as the theoretical reference for the prediction of vertical sweep efficiency of water-flood- ing thick oil reservoirs.