An Accurate Prediction Model of Wellbore Pressure in Deep Wells Considering Segmental Rheological Patterns
The wellbore temperature and pressure distribution range of deep and ultra-deep wells is wide,the rhe-ology of drilling fluid is also obviously affected by ultra-high temperature and ultra-high pressure,and the predic-tion error of wellbore pressure based on conventional rheological mode is big.After rheological tests of water-based and oil base drilling fluids with temperatures from 20℃to 220℃and pressures from 0.1 MPa to 200 MPa,a selection method of segmented rheological model of drilling fluid based on different temperature and pres-sure ranges was proposed,and an accurate prediction model of wellbore pressure considering multiple influences established in this paper.The results show that the variation law of rheological curve of drilling fluid is inconsis-tent with the variation of temperature and pressure,and a single rheological model cannot fully characterize the rheological properties of drilling fluid.Herschel-Bulkley mode has better applicability to the water-based drilling fluid rheological property below 100℃and oil-based drilling fluid below 140℃,the Ross mode has better appli-cability in other temperature ranges.The effect of the segmented rheological mode on the bottomhole pressure was obvious.Comparison of the model calculation results with the measured data shows that the prediction error of bottomhole pressure was less than 0.3 MPa,and the prediction error of the standpipe pressure was less than 0.6 MPa.The wellbore pressure prediction error in water-based drilling fluid was smaller than that in oil-based drilling fluid.This study can provide a theoretical analysis method for accurate prediction of wellbore pressure in deep and ultra-deep wells.
deep wellssegmented rheological modewellbore pressuredrilling fluid
NETL
NSTL
万方数据
维普
