考虑酸蚀蚓孔效应的酸液滤失模型及应用

碳酸盐岩高排量酸压施工过程中由于酸蚀蚓孔不可避免地生成,常常出现酸液过度滤失情况,严重制约了酸蚀主裂缝的延伸。因此,酸蚀蚓孔扩展机理研究和考虑酸蚀蚓孔滤失的酸压计算模型研究非常重要。在研究酸蚀蚓孔发育机理和酸液滤失机理基础上,将蚓孔沿长度方向分段,考虑每段蚓孔上酸液流动摩阻、流速、压力以及酸岩反应等对酸蚀蚓孔几何尺寸的影响,同时考虑基质中流体流动的影响,建立了考虑酸蚀蚓孔滤失的酸压数学模型。模型能够模拟和再现注酸过程中酸蚀蚓孔随注入排量、施工压力和时间而扩展的过程以及酸液的滤失量随时间的变化情况,与Frac PT10.1软件相比,计算结果更接近酸压实际情况。

NOVEL CALCULATION METHOD OF THE ACID LEAK-OFF CONSIDERING THE EFFECT OF ACID WORMHOLE

Compared with the matrix acidizing,wormhole is formed inevitably during the process of high pumping rate acid fracturing treatment,which leads to serious acid leak-off and short acid penetration distance and leads to a bad effect on the carbonate stimulation,or even brings the treatment into failure.Therefore,the acid wormhole propagation mechanism study and the novel calculation model for the acid leak-off in the acid fracturing is very important.In this paper,a novel model has been developed to analysis the initiation and propagation mechanisms of wormhole and the acid leak-off mechanisms during the process of the acid fracturing.The model can simulate the propagation process of wormhole,and also can shows the changes of propagation process and leak-off of acid with pumping rate and time.