压裂液返排期间放喷油嘴的磨损规律研究

压裂液返排期间,由于支撑剂的回流返吐导致放喷油嘴磨损严重,不仅增加了更换油嘴的成本,而且影响压裂施工效果。为了延长放喷油嘴的使用寿命,基于光滑粒子流体动力学(SPH)和有限元(FEM)的耦合方法,对压裂液返排期间放喷油嘴的磨损规律进行数值模拟研究。以磨损速率为判断标准,优化设计了放喷油嘴的内流道结构,优选了油嘴材料,探讨了支撑剂质量分数和粒径对油嘴磨损程度的影响。研究结果表明:放喷油嘴收缩段与直线段的过渡段和出口处的磨损最严重,优选油嘴的内流道结构为流线形,收缩段长度为25 mm,整体长度为42 mm,材料为陶瓷;随着支撑剂质量分数和粒径的增加,放喷油嘴的磨损速率均呈现先增大后减小的规律;优化的放喷油嘴耐磨性强,使用寿命长,可保证压裂液返排施工高效进行。研究结果可为高压高含砂条件下的耐磨油嘴设计提供参考。

Study on Erosion Wear of Discharge Nozzle during Fracturing Fluid Backflow

During the backflow of the fracturing fluid,the discharge nozzle is seriously worn due to the backflow of the proppant,which not only increases the cost and labor intensity of the nozzle replacement,but also affects the fracturing performance.To prolong the service life of the nozzle,based on the smooth particle hydrodynamics(SPH)and finite element modeling(FEM)coupling method,the numerical simulation of the wear of the nozzle during the backflow of the fracturing fluid is carried out.Taking the wear rate as the criterion,the internal flow channel structure of the discharge nozzle is optimized,and the nozzle material is optimized.The influence of proppant mass fraction and particle size on the wear of the nozzle is discussed.The results show that the wear of outlet and the transition part of the contraction section and the straight section of the nozzle is the most serious.The streamline inner flow channel of the nozzle is selected.The length of the contraction section is 25 mm and the overall length is 42 mm.The ceramics is selected as the material.With the increase of proppant mass fraction and particle size,the wear rate of the nozzle increases first and then decreases.The optimized nozzle has strong wear resistance and long service life,which can guarantee the efficient fracturing fluid backflow.The study results can provide references for the design of wear-resistant nozzle under high pressure and high proppant content.