摘要
油气钻井过程中,破碎的岩屑在井筒钻井液中存在着自由沉降的现象,为了防止和避免岩屑沉积造成沉砂卡钻等井下安全事故,需要研究岩屑颗粒的沉降规律、预测岩屑沉降的末速度。为此,基于Stokes定律和Newton-Rittinger模型,提出了黏性阻力占比系数与压差阻力占比系数的概念,应用最小二乘法对实验数据回归得到阻力占比系数方程,分别推导出岩屑颗粒在牛顿流体与幂律流体中沉降时非斯托克斯区域的阻力计算模型,并通过该模型依据沉积实验数据对岩屑颗粒的沉降末速度进行计算和分析。研究结果表明:(1)岩屑颗粒在幂律流体中沉降时,所受到的黏性阻力和压差阻力不仅与颗粒雷诺数相关,而且还与流性指数及稠度系数相关;(2)岩屑颗粒在牛顿流体中沉降,当颗粒雷诺数小于2.944 6时黏性阻力大于压差阻力,当颗粒雷诺数大于2.944 6时压差阻力大于黏性阻力;(3)颗粒雷诺数小于1.11时岩屑沉降主要考虑黏性阻力,颗粒雷诺数介于1.11~500时岩屑沉降受到黏性阻力与压差阻力的共同作用,颗粒雷诺数大于500时压差阻力在岩屑沉降中占主导作用。结论认为,借助于该计算模型,当钻井液为牛顿流体时,可以预测颗粒雷诺数介于0~105的岩屑沉降末速度;当钻井液为幂律流体时,可以预测颗粒雷诺数介于0~105、流性指数介于0.062 3~1的岩屑沉降末速度;上述范围能够满足钻井工程中对于岩屑沉降速度进行预测的需求。
In the process of oil and gas well drilling, the broken cuttings settle freely in the drilling fluid in the wellbore. To avoid downhole accidents caused by the cuttings settlement, therefore, it is necessary to study the cuttings settlement laws and predict the terminal cuttings settlement velocity. In this paper, a concept of resistance scale between viscosity and differential pressure was put forward based on the Stokes law and Newton-Rittinger model. Then, the equation of resistance scale was obtained by regressing the experiment data using the least square method. Finally, the resistance scale calculation model was derived for non-Stokes zone during the cuttings settlement in Newtonian fluids and power-law fluids. Furthermore, based on experimental data, the terminal cuttings settling velocity was calculated by using the new models. The following results were obtained. First, the viscosity and differential pressure on the cuttings during their settlement in power-law fluids are not only related to the particle Reynolds number, but to the flow behavior index and consistency index. Second, during the cuttings settlement in Newtonian fluids, the viscosity is higher than the differential pressure if the particle Reynolds number is less than 2.944 6. Third, the differential pressure is higher than the viscosity if the particle Reynolds number is higher than 2.944 6. Fourth, when the particle Reynolds number is lower than 1.11, the viscosity plays a dominant role in cuttings settlement; when the number is 1.11–500, cuttings settlement is under the joint effect of viscosity and differential pressure; when the number is higher than 500, the differential pressure is dominant. In conclusion, this calculation model can be used to predict the terminal settlement velocity of cuttings with a particle Reynolds number of 0-105 when the drilling fluid is a Newtonian fluid, and the terminal settlement velocity of cuttings with a particle Reynolds number of 0-105 and a flow behavior index of 0.062 3-1 when the drilling fluid
作者
孙晓峰
张克博
陈烨
曲晶瑀
汤捷
屈俊波
Sun Xiaofeng, Zhang Kebo, Chen Ye, Qu Jingyu, Tang Jie , Qu Junbo(School of Petroleum Engineering, Northeast Petroleum University, Daqing, Heilongjiang 163318, Chin)
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2018年第5期94-102,共9页
Natural Gas Industry
基金
国家科技重大专项"复杂结构丛式井钻井水力学与井眼清洁配套技术"(编号:2017ZX05009-003)
国家自然科学基金面上项目"液力-磁耦合自旋转井眼清洁工具的旋转传动机理研究"(编号:51674087)
"基于精细回压控制的地层-井筒多相流耦合机理研究"(编号:51474073)
关键词
油气钻井
井筒钻井液
岩屑沉降
速度预测
黏性阻力
压差阻力
阻力系数
牛顿流体
幂律流体
Oil and gas well drilling
Drilling fluid in wellbore
Cutting settlement
Velocity prediction
Viscosity resistance
Differential pressure
Resistancescale
Newtonian fluid
Power-law fluid
