水平井泡沫携砾石充填数值模拟

在进行疏松砂岩水平井砾石充填完井过程中,以往均采用牛顿流体作为携砂液。泡沫流体作为非牛顿流体,比牛顿流体具有更好的携带性能,并且具有低滤失性。针对水平井砾石充填作业发生提前堵塞和携砂液进入地层问题,借鉴水平管流的固液两相流动机制,建立水平井泡沫携砾石充填两层数学模型,并且对泡沫在水平井中流动的摩阻系数进行讨论。对偏心率、砾石直径、砾石密度及泡沫干度对砾石充填效果的影响进行计算分析,并以充填效率、砂床高度及综合评价指标表征充填效果。结果表明:随偏心率增大,充填评价指标趋于增加,但增加的幅度较小;随砾石直径、砾石密度及泡沫干度的增加,充填指标趋于降低;泡沫作为携砂液进行砾石充填比牛顿流体具有更好的充填效果。

Numerical simulation for foam as sand carrying fluid during gravel packing in horizontal wells

Gravel packing has been an important completion method for horizontal wells in unconsolidated sand reservoirs, and Newtonian fluids were normally used as sand carrying fluid. As foam to be a non-Newtonian fluid, it has better carrying capability and low filtration. In the horizontal well gravel packing, early blockage can occur, which can limit the sand carrying fluid into the deep formation. In this study, a two-stage mathematical model for gravel carrying by foam fluids was established based on two-phase flow mechanism for solid-liquid flow in gravel packing process in horizontal wells. The friction factor for foam flow in horizontal wellbore was considered. The influences of well ''s eccentricity, the size and density of gravels and the foam quality on the performance of gravel packing were investigated. A packing efficiency index, sand bed height index and a comprehensive evaluation index were defined as the evaluation parameters. It is concluded that well ''s eccentricity has a positive effect on the performance of gravel packing, while the packing efficiency decreases with the increase of the size and density of gravels and foam quality. The gravel packing efficiency and its performance can be significantly improved in horizontal wells using foams as non-Newtonian sand carrying fluid than normal Newtonian fluids.