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在石油工业中,纤维被广泛应用于提高钻井液和压裂液的固相运移能力,研究颗粒在含纤维流体中的沉降速度可以为纤维钻井液及压裂液性能评价与优化设计提供依据。本文针对球形颗粒在含纤维幂律流体中的沉降速度进行研究,拟建立一个考虑不同雷诺数与纤维浓度的颗粒沉降速度预测模型。开展了球形颗粒在含纤维幂律流体中沉降速度全参数实验,考虑的变量参数有:颗粒粒径、颗粒密度、基液流变性及纤维浓度。结果表明:在实验条件下,加入纤维使基液的表观黏度有少量增加;随着纤维浓度的增大,颗粒沉降速度逐渐降低,表明纤维对颗粒产生一个机械阻力作用,定义为纤维阻力。与黏性阻力系数类似,本文定义无因次纤维阻力系数来定量表征纤维阻力的大小;定义与颗粒沉降速度无关的阿基米德数为总阻力系数(纤维阻力系数与流体阻力系数之和)与颗粒雷诺数的函数。基于实验数据,发现在实验沉降速度下,颗粒雷诺数与无因次阿基米德数在双对数坐标系中符合线性关系,据此拟合得到了最终的颗粒沉降速度预测模型。与实验数据相比,该模型平均相对误差为12.39%,符合精度要求。该模型适用的雷诺数范围为(0.002~324),纤维浓度范围为(0.02%~0.1%)。本研究对纤维在石油工程中的应用具有一定的指导意义。
In the petroleum industry, fibers are widely used to enhance the solid migration ability of drilling fluids and fracturing fluids. Studying the sedimentation velocity of particles in the fluid containing fibers can provide a basis for the evaluation and optimization of the performance of fiber drilling fluid and fracturing fluid . In this paper, the sedimentation velocity of spherical particles in fiber-containing power law fluid is studied, and a prediction model of particle sedimentation velocity considering different Reynolds numbers and fiber concentrations is proposed. The whole parameters of the settling velocity of spherical particles in the fiber-containing power law fluid were investigated. The parameters of the variables considered were particle size, particle density, base fluid rheology and fiber concentration. The results show that under the experimental conditions, the apparent viscosity of the base fluid increases slightly with the addition of the fiber. With the increase of the fiber concentration, the particle settling velocity gradually decreases, indicating that the fiber has a mechanical resistance to the particles and is defined as the fiber resistance. Similar to the viscous drag coefficient, dimensionless fiber drag coefficient is defined to quantitatively characterize the fiber drag size. Define the total drag coefficient (the sum of the fiber drag coefficient and fluid drag coefficient), which is independent of the particle sedimentation speed. As a function of particle Reynolds number. Based on the experimental data, it is found that the particle Reynolds number and the dimensionless Archimedean number fit a linear relationship in the double logarithmic coordinate system under the experimental settling velocity, and the final particle sedimentation velocity prediction model is fitted. Compared with the experimental data, the average relative error of this model is 12.39%, which accords with the precision requirement. The model is suitable for Reynolds number range (0.002 ~ 324), fiber concentration range (0.02% ~ 0.1%). This study has certain guiding significance for the application of fiber in petroleum engineering.