天然裂缝性碳酸盐岩酸化数学模型研究

当天然裂缝性碳酸盐岩地层在低于岩石破裂压力下进行酸化处理时,其酸化过程既不同于一般的基质酸化,也不同于酸压。为此,建立了一个新的天然裂缝性碳酸盐岩酸化数学模型,模型包括酸液的质量守恒,酸的传递与反应和裂缝宽度随酸溶蚀的变化。文中对裂缝壁面的酸滤失和酸岩反应处理也采用了新的方法。用新的酸化模型对数字生成的粗糙表面裂缝进行模拟,可以预测裂缝的酸刻蚀特征与裂缝宽度、裂缝表面粗糙度和酸滤失速度之间的关系。这个模型还可预测裂缝中的压力、酸液浓度和裂缝宽度随时间和位置的变化。

Study on mathematical model of the acidizing process in naturally fractured carbonate rock

When acid treatment of a naturally fractured carbonate formation is below fracture pressure, the acidizing process is neither different from common matrix treatment, nor from acid fracturing. As for this reason, a mathematical model of acidizing naturally fractured carbonates has been developed. The model includes mass conservation of acid liquid, as well as acid transmission and reacting, and the fracture width variance along with the change of acid dissolution. A new approach is also applied in acid leak - off and acid - rock reactions of fractured walls. With this new acidizing model for numerically generated rough - surfaced fractures, it can predict acid etching patterns and its relations with the fracture width, surface roughness, and leak-off rate. Beyond that, it also can predict the variance of pressure, acid concentration and fracture width along with the changing of time and space.