高粘度酸液在人工裂缝中流态规律研究

Study on flow rule of high viscosity acid in hydraulic fracture

关键词:  酸化压裂 高粘度酸液 流态 雷诺数 Z值稳定性

Key words:  acid fracturing, high viscosity acid, flow, Reynolds number, Z value stability

摘要:

随着油气田勘探开发应用技术的不断深入，高粘度酸液越来越多地应用到不同类型的复杂致密油气藏的储层改造中。高粘度酸液可以降低滤失量、减缓反应速率，实现酸液的深度穿透。研究高粘度酸液在人工裂缝中的流动状态对模拟其滤失和酸岩反应过程具有重要意义。运用幂律流体的雷诺数分析法和稳定性Z值法，对高粘度酸液在地层裂缝中的流动状态进行了研究。分析发现影响高粘度酸液流态的主要因素有酸液排量、裂缝高度、裂缝宽度、酸液稠度系数、流态指数。其中酸液的稠度系数为主控因素。当稠度系数小于0.015 Pa·sn时，常规施工中的地层酸液为紊流状态。因此普通酸酸化时的地层酸液为紊流状态，而常规酸压中高粘度的稠化酸和交联酸在地层中一般为线性层流状态。研究认为增加排量对酸液的流态影响不大

Abstract:

With the further development of petroleum exploration and exploitation technologies, high-viscosity acidizing fluid has been applied to reservoir stimulation of varieties of complex tight oil and gas accumulations, to decrease the filtration rate and the reaction rate, so as to achieve more penetration depth of the acidizing fluid. The research about fluid state of high-viscosity acidizing fluid in artificial fractures shows great significance in modeling the processes of filtration and acid rock reaction. In this paper, Reynolds number analysis and Z value stability methods of power law fluid are used,to study the flow state of high viscosity acidizing fluid in formation fractures. Results show that main controlling factors which affect flow state of high viscosity acidizing fluid include acid displacement, fracture height, fracture width,consistency coefficient and flow state index, in which the consistency coefficient is the most important factor. When the consistency coefficient is below 0.015 Pa·sn,formation acidizing fluid in conventional construction turns into turbulent state. Therefore the formation acidizing fluid is turbulent in ordinary acidify, while gelled acid and cross-linked acid with high-viscosity are always linear laminar flow under conventional acid fracturing. It is resulted that increasing the delivery volume has little effect on the flow state of acidizing fluid