基于冲蚀分析的双簇水力喷射器结构优化研究

发布时间：2018-05-10 20:26

本文选题：冲蚀 + 水力喷射器　；参考：《西安石油大学》2017年硕士论文

【摘要】：水平井水力喷射压裂技术是低渗透油气田增产的主要方法。相对于单级喷射工具,双簇水力喷射器可以同时对两个油气层进行喷射压裂,可提高压裂施工效率。但在其应用过程中,高速携砂流体会对双簇水力喷射器上、下两级喷枪造成不同程度的冲蚀损伤,导致喷射器整体损坏。基于双簇水力喷射器在应用过程中的冲蚀问题,利用自制的喷射式冲蚀实验台,完成喷射器本体材料35CrMo钢的冲蚀实验。研究了携砂压裂液的喷射角度和喷射速度对材料失重量的影响。结果表明,35CrMo钢的冲蚀失重量随喷射角度的增大先增大后减小,至喷射角度为45度时达到峰值;冲蚀失重量随喷射速度的增大而增大。根据实验结果拟合得到了适用于水力喷射压裂工况的冲蚀计算模型。采用离散相多相流数值模拟方法,分析了双簇水力喷射器初始结构时的液-固两相流场,并运用实验得到的冲蚀模型计算喷射器内壁面的冲蚀壁厚损失。发现流经双簇水力喷射器下级喷嘴的砂流量大于上级喷嘴;喷枪内壁面的冲蚀壁厚损失较外壁面大一个量级,下级喷枪内壁面的冲蚀壁厚损失大于上级喷枪,最大壁厚损失发生在下级喷枪内壁面。随着入口排量的增大,流经各段喷嘴的砂粒流量和喷枪内壁面的冲蚀壁厚损失同时增大。为改善双簇水力喷射器上、下两级喷枪流量及冲蚀损失的差异性,通过改变上、下级喷枪喷嘴数量、喷嘴直径和簇间距对双簇水力喷射器的结构进行了优化研究。通过相同工况下的数值模拟对比多种不同结构优化方案对流量和冲蚀的影响。结果表明,上级喷枪采用6个6mm直径喷嘴与下级喷枪采用6个5mm喷嘴组合的方案时,对初始组上、下级喷嘴砂流量和内壁面冲蚀损失差异性的优化效果最佳。而簇间距对流经各段喷嘴的液体、砂粒质量流量及内壁面的冲蚀壁厚损失影响微弱。创新性的提出了喷射器前端增加扰流短接的优化方案,并对扰流短接内螺旋槽结构参数进行了优化。通过合理组合喷嘴直径以及加装最优结构参数的扰流短接,能够明显改善上、下级喷嘴砂流量及砂含量,避免双簇水力喷射器上、下级喷嘴冲蚀壁厚损失的差异性。
[Abstract]:Hydraulic injection fracturing in horizontal wells is the main method for increasing production in low permeability oil and gas fields. Compared with single stage injection tools, double cluster hydraulic injectors can be used to spray fracturing two oil and gas layers at the same time, and the fracturing efficiency can be improved. However, in the process of application, the high speed sand carrying fluid will cause erosion damage to the next two stages of spray gun on the double cluster hydraulic ejector, resulting in the overall damage of the ejector. Based on the erosion problem of the double cluster hydraulic ejector in the application process, the erosion experiment of 35CrMo steel was completed by using the self-made jet erosion test bench. The influence of injection angle and velocity of sand carrying fracturing fluid on material weight loss was studied. The results show that the erosion weight of 35CrMo steel increases first and then decreases with the increase of jet angle, and reaches the peak value when the injection angle is 45 degrees, and the erosion weight increases with the increase of jet velocity. According to the experimental results, the erosion calculation model suitable for hydraulic jet fracturing was obtained. The liquid-solid two-phase flow field during the initial structure of a double-cluster hydraulic injector is analyzed by using the numerical simulation method of discrete phase multiphase flow. The erosion wall thickness loss on the inner wall of the ejector is calculated by using the experimental erosion model. It is found that the sand flow through the lower nozzle of the double cluster hydraulic ejector is larger than that of the upper nozzle, the loss of the erosion wall thickness of the inner surface of the spray gun is one order of magnitude greater than that of the outer wall, and the loss of the erosion wall thickness of the lower level spray gun is greater than that of the upper spray gun. The maximum wall thickness loss occurs on the inner wall of the lower spray gun. With the increase of inlet displacement, the flow rate of sand particles flowing through the nozzle and the erosion wall thickness loss of the inner wall of the spray gun increase simultaneously. In order to improve the difference of the flow rate and erosion loss between the upper and lower stages of the double cluster hydraulic injector, the structure of the double cluster hydraulic injector was optimized by changing the number of the lower jet nozzle, the diameter of the nozzle and the cluster spacing. The effects of different structural optimization schemes on flow rate and erosion are compared by numerical simulation under the same working conditions. The results show that when the upper gun adopts the combination of 6 6mm diameter nozzles and 6 lower 5mm nozzles, the optimal results are obtained for the difference of sand flow rate and erosion loss on the inner surface of the lower nozzles in the initial group. The effect of cluster spacing on the loss of liquid, sand mass flow and the erosion wall thickness of the inner wall surface is weak. An innovative scheme of adding scrambling short connections to the front end of the injector is proposed, and the structural parameters of the spiral groove in the scrambling short connection are optimized. By reasonably combining the nozzle diameter and adding the optimal structural parameters to the scrambling short connection, the sand flow rate and sand content of the lower nozzle can be obviously improved, and the difference of the erosion wall thickness loss of the lower nozzle on the double cluster hydraulic injector can be avoided.
【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE934.2

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