文昌海相水驱砂岩油藏驱油效率新认识

驱油效率是表征油藏驱油能力的重要参数，传统方法是利用短岩心驱替实验结果来标定油藏的驱油效率，并进一步评价油藏的开发潜力，文昌13-2油田Ⅱ油组目前采出程度为56.8%，已经远大于早期短岩心测试水驱油效率47.08%。这表明传统标定方法存在不合理性，必须重新研究文昌13-2油田的水驱油效率。此文利用分形维动态相渗、RPM饱和度测井、密闭取心饱和度测试及长岩心水驱油实验方法对Ⅱ油组水驱油效率进行了综合研究。分析表明长岩心驱替实验结果更适合标定文昌海相水驱砂岩油藏的驱油效率，最终标定文昌13-2油田Ⅱ油组驱油效率为84.27%。这在水驱油效率研究方面有了颠覆性的认识。通过将水驱油效率研究成果应用到油藏数值模拟研究中，提高了油田剩余油认识精度，能更好地指导油田后期调整挖潜工作的开展。

New Understanding of Water Displacement Efficiency in Water Flooded Sandstone Reservoirs of Wenchang Oilfield

The water displacement efficiency is an important parameter for characterization of reservoir displacement capability. Traditionally, short core is used in the displacement experiment to calibrate the water displacement efficiency, and further evaluate the reservoir development potential. However, this method is not suitable in Wenchang 13-2 Oilfield because the present reserve recovery of 56.8% in the second oil zones of this field has exceeded the displacement efficiency of 47.08% previously calculated by the experiment with short core in the early years. This indicates that the traditional calibration method is not reasonable for Wenchang 13-2 Oilfield, and it is necessary to re-determine the water displacement efficiency of Wenchang 13-2 Oilfield. Based on the fractal dimension relative permeability curve, production log, and saturation test and water displacement efficiency with long core experiment, the authors conducted the study of the water displacement efficiency in the second oil zones of this field. It indicates that the parameter of displacement experiment with long core is more suitable for calibrating the water displacement efficiency of water flooded sandstone reservoir of Wenchang 13-2 Oilfield. The update water displacement efficiency 84.27%, brought a new understanding about the water displacement efficiency. Also, its application in the numerical reservoir simulation results in great improving in the estimation of the residual oil, and can be used to guide the adjustment and tapping potentials of the oil field in later stage.