基于组合式平板模型预测曲面裂缝数字岩心渗透率的方法

针对碳酸盐岩微裂缝系统中曲面裂缝特征复杂,流动模拟难以进行的问题,提出一种求解曲面裂缝数字岩心渗透率的方法。首先构建平板裂缝数学模型,并利用格子布尔兹曼方法,得到以开度和倾角为基本参数的微裂缝模型的流动规律;其次基于平板模型的流动规律和曲面裂缝的基本特征将平板模型进行组合求解曲面裂缝的绝对渗透率;最后进行实例验证。结果表明该方法准确有效,可在识别出裂缝相关参数后预测岩心绝对渗透率,避免了大量数值模拟,提高了计算效率。

Permeability prediction in digital core with curved fractures based on combined plate model

It is difficult to simulate the fluid flow in micro-fracture system because of the sophisticated characteristics of the fractures in carbonate reservoirs. A method was developed to predict the absolute permeability of carbonate rock samples using a digital or numerical rock technique, in which curved fractures were considered. Firstly, a numerical simulation model of fluid flow in a system with flat fractures was established, and the effects of its basic parameters (i.e. fracture dip and fracture opening) on the flow behavior were determined using a lattice-Boltzmann method. Secondly, the absolute permeability of curved fractures was predicted based on the combination of fluid low in the flat model and the basic characteristics of a curved fracture system. Experimental work was also conducted to prove the accuracy of the numerical method. The results show that this method is accurate and effective. The absolute permeability can be directly predicted when the fracture parameters are identified, and the calculation efficiency is improved.