Abstract: During the gravel-packing process in horizontal wells,the alpha wave packing is always together with the filtration of fluid carrier into formation and mass exchange of fluid flowing through the screen slots.Considering these characteristics,the equations for mass and momentum conservation of gravel and fluid in two flow systems were established.One system is solid-fluid two-phase flow system in wellbore annular,and the other is single-phase flow system in wash pipe and screen annular.The coupling equations of the two flow systems and time-dependent numerical model for horizontal gravel-packing were evolved.By the model,a program package was designed to visually simulate the horizontal gravel-packing process in real-time,calculate the packing percent and predict occurrence of premature plugging.Full packing and premature plugging were simulated respectively,and the dynamic characteristics of all parameters were analyzed.It is indicated that the model is reasonable.The slurry pump rate,gravel concentration,fluid viscosity,diameter of wash pipe and filtration velocity all have some ef- fects on the packing efficiency.

Key words: horizontal well, gravel packing, numerical simulation, mathematical model, packing effect

摘要： 分析了水平井砾石充填过程及其特征,考虑携砂液向地层的滤失以及井筒环空、冲筛环空之间的流体质量交换,分别建立了井筒环空、冲筛环空2个独立流动系统的砾石、携砂液的质量和动量守恒方程以及各系统间的流动耦合方程,得到描述水平井砾石充填过程的时间相关数学模型。开发模拟软件对整个充填过程能进行可视化模拟,预测堵塞的发生及堵塞位置、充填率等。使用软件对完全充填、提前堵塞两种情况进行了算例模拟计算,分析了充填过程中的各动态参数的变化规律,模拟及分析结果符合水平井砾石充填的基本特征。砂浆排量、携砂比、携砂液粘度、冲筛比、滤失强度等因素对充填效果有一定影响。

关键词: 水平井, 砾石充填, 数值模拟, 数学模型, 充填效果