水平井砾石充填可视化模拟及充填效果评价

水平井砾石充填过程是复杂条件下的固液两相变质量流动,存在携砂液向地层的滤失以及井筒环空、冲筛环空间的流体质量交换。根据井筒、冲筛环空两个独立流动系统的砂、液质量和动量守恒方程,以及各系统间的流动耦合方程,建立了描述α充填过程的时间相关数学模型。补充辅助方程后可数值求解,并提出了充填效果综合评价指标的计算方法。利用数值模型开发软件可对整个充填过程进行可视化模拟。结果表明,模型和软件对顺利充填和提前堵塞两种情况均可适用,并能预测是否堵塞、堵塞位置、充填率以及计算充填效果综合评价指标。分析了充填过程中的各动态参数的变化规律,在充填前沿位置,由于沉积砂床消失,系统间窜流最为明显,各动态参数在充填前沿前后均有剧烈变化。

Visual Simulation of horizontal gravel-packing and its effect evaluation

The process of gravel-packing in horizontal wells is really a solid-liquid two-phase flow in complicated conditions,which concerns the filtration flow of carrier fluid into the formation and the exchange flow through the screen slots between two flow system.That is,solid-fluid two phase flow in wellbore annular and single phase flow in wash pipe and screen annular.According to the mass and momentum conservation equations of gravel and fluid,with the coupling equations,the time-dependent numerical model for α step in horizontal gravel-packing is evolved.And the calculation method for the evaluation index of packing effect is put forward.The model and software can be used to simulate the entire packing process visually for full packing and premature plugging,predict plugging point and packing efficiency,and calculation evaluation index.The change characters of dynamic parameters during the packing process are also analyzed.At the packing forehead,because of the sudden disappear of sand bed,the exchange flow rate is relatively very evident and other flow parameters also change obviously across the packing forehead.