考虑低渗点启动压力梯度的中东孔隙型碳酸盐岩油藏波及系数修正方法

 根据中东地区孔隙型碳酸盐岩油藏渗透率分布范围大、低渗与中高渗渗流规律并存的特征，针对低渗点存在启动压力梯度而难以动用的问题，采用数值模拟方法分析低渗点启动压力梯度对油藏波及系数的影响规律，通过耦合低渗点启动压力与井间驱替压力分布，提出考虑低渗点启动压力梯度的孔隙型碳酸盐岩油藏波及系数修正方法。以中东地区M油藏为例进行应用分析，计算得到的渗透率为5×10^-3~35×10^-3 μm²、变异系数为0.6~0.8时，波及修正系数分布范围为0.75~0.99，证明了该孔隙型碳酸盐岩油藏波及系数修正方法的可靠性和实用性。

Correction of sweep coefficient for the porous carbonate reservoirs in the Middle East with consideration of start-up pressure gradient in low permeability points

Based on the characteristics of the large scope permeability distribution, and the joint action of the seepage law for both low permeability and medium to high permeability, aiming at the problem of the recovery restriction for low permeability points caused by the start-up pressure, the influence of the start-up pressure gradient of low permeability points on the sweep coefficient is studied by the numerical simulations. Also, by coupling the start-up pressure gradient and the displacement pressure distribution for the low permeability point, the correction method for the sweep efficiency is established. Result shows that the lower the reservoir permeability and the higher the permeability variation, the greater the influence of the start-up pressure of the low permeability points on the sweep coefficient. Taking the M oil reservoir in the Middle East as an example, the application analysis is carried out. When the reservoir permeability is between 5~35×10^-3 μm² and the permeability variation is between 0.6~0.8, the range of the correction coefficient is about 0.75~0.99, which in turn can correct the calculation of the sweep efficiency in the industry standards.