固井用油井水泥颗粒干混特性的数值模拟

在固井作业中,湿混方式混合时间长、原料浪费严重、环境污染大,因此气力干混技术日益得到重视。为探究干混时油井水泥与外掺料混合均匀程度的变化规律,确定最佳操作条件,利用FLUENT软件,采用欧拉-欧拉多相流模型对混拌罐内油井水泥颗粒和外掺料颗粒的混合过程进行数值模拟,分析了进气速度、进气口数量、物料装填顺序以及颗粒物性等因素对混合情况的影响。结果表明：气流速度较低时油井水泥与外掺料混合不均匀,气流速度过高则会出现颗粒局部集中；对本算例而言,气流为1m/s时可获得较好的混合效果；增加进气口数量不能明显改善颗粒混合的均匀程度；初始装填时,密度最大的颗粒不应置于最底层；颗粒密度对混合情况有较大影响,而粒径的影响较小。

Numerical simulation of dry mixing characteristics of oil well cement particles in cementing operations

In cementing operations, oil well cement needs to be mixed with admixtures to improve its performance. The early wet mixing method has shortages of long mixing duration, serious waste of raw materials and heavy environmental pollution, thus pneumatic dry mixing technology has drawn more attention recently. In order to investigate the variation law of mixing uniformity of oil well cement and admixture in dry mixing and determine the optimal operating condition. In this paper, the mixing process of oil well cement particles and admixture particles in the mixing tank is numerically simulated by using FLUENT and Euler-Euler multiphase flow mode. The effects of inlet air velocity, air inlet number, materials loading sequence as well as particle properties on mixing were analyzed. The results show that when the air velocity is too low, oil well cement and admixture unevenly mix. On the contrary, when the air velocity is too large, there will be a concentrated distribution of the particles. For the given case, the optimal air velocity is 1m/s. Moreover, increasing the number of air inlets can not significantly improve the uniformity of particle mixing. When loading the materials, particles with the highest density should not be placed at the bottom layer. The mixing performance is significantly affected by particle density, while particle size has no marked influence on mixing efficacy.