Temperature field analysis on the highly-deviated wellbore in backwashing condition

Based on the measured borehole trajectory, a prediction model of temperature field of highly-deviated wells in backwashing condition is established. To verify the model, a test instrument to measure the temperature variations in the wellbore is developed and used to measure the temperature of two typical highly-deviated wells in backwashing condition. The comparative analysis shows that the wellbore temperature predicted by the model is close to that measured in field with the relative error less than 8%. The model was further used to analyze the influence of liquid-injection speed and injection time on the temperature distributions of oil pipe, annulus space and radial direction under the backwashing operation with original-temperature and hot washing liquid. It is found that for the backwashing operation with original-temperature washing liquid, the temperature at the lower part of the shaft is most affected by the displacement rate and backwashing time, whereas the curve section and the lower part of the shaft are most affected by the displacement rate and backwashing time in hot washing operation. Along the depth of the borehole, there is a constant temperature section which is almost unaffected by displacement rate and backwashing time. The radial heat transfer analysis shows that the heat exchange range is not large and near the wellbore.