超深水平井钻井水力参数优选

基于传热学理论和井筒流动特性,通过建立超深水平井的井筒物理模型和温度场模型,考虑螺杆钻具的工作特性,以钻头和螺杆钻具组合的最大水力能量作为优选目标,建立了水力参数优选模型,分析了温度、压力对最小携岩排量的影响,并计算了最优排量和其他水力参数。结果表明:与不考虑温度、压力影响时相比,考虑温度、压力影响时的最小携岩排量增加了1倍;最小携岩排量随着钻井液密度和塑性黏度的降低而增大,塑性黏度是其主要影响因素;不同时刻的最小携岩排量存在一临界点,在临界点上、下井段确定最小携岩排量时,应采用不同时刻对应的最小携岩排量。因此,在超深水平井复合钻井时,应充分考虑温度、压力对水力参数优选的影响,以保证井眼清洁,提高钻井效率。

Optimization of drilling hydraulic parameters for ultra-deep horizontal well

By establishing the physical wellbore model and temperature field model,a hydraulic parameter optimization model for ultra-deep horizontal well under compound drilling condition was established based on heat transfer theory and wellbore flow characteristics,and fully considering the influence of working performance of screw drilling tool on hydraulic parameters optimization.An iterative algorithm is proposed to analyze the effects of temperature and pressure on minimum cutting carrying displacement and pressure loss.The results show that the minimum cutting carrying displacement doubled compare with the temperature and pressure not considered.The minimum cutting carrying displacement increased with the decrease of drilling fluid density and plastic viscosity,the plastic viscosity is the main factor.In different cycle time,the minimum cutting carrying displacement has a critical point.The corresponding minimum cutting carrying displacement should be selected in different time at well section of higher or lower than the critical point.So it is necessary to consider the influence of temperature and pressure on the optimization of hydraulic parameters for ultra-deep horizontal well under compound drilling condition to ensure wellbore cleaning and improve drilling efficiency.