Research on Wellbore Temperature Prediction Model and Cooling Method of Ultra-deep Well with Small Hole
The problem of bottom hole high temperature is prominent in the ultra-deep small hole drilling in Shunbei block.It is of great engineering significance to clarify the distribution law of wellbore temperature field and explore efficient cooling method to ensure the drilling safety in this area.Based on the ultra-deep small hole drilling process,this paper established a transient wellbore heat transfer model suitable for ultra-deep small holes using measured MWD data and commercial software Drillbench for comparison and verification,considering the effects of various heat sources such as drilling fluid viscosity dissipation,drill string eccentricity,rotation and bit rock breaking on wellbore temperature.The predicted value of this model is more consistent with the data while drilling,and the error is less than 2％.The results show that the thermal insulation of drill string can reduce the bottom hole temperature by 33 ℃,and other methods such as drilling speed and displacement can reduce the bot-tom hole temperature by 3～10 ℃.The cooling efficiency of surface cooling method shows a significant marginal decreasing effect,that is,the deeper the well,the more limited the cooling capacity.At present,the cooling effect of single cooling method is not significant enough,so it is suggested to combine multiple cooling methods to ef-fectively reduce the wellbore temperature.This study can provide theoretical guidance for accurate prediction of wellbore temperature and optimization of cooling method in ultra-deep wells with small holes.
temperature fieldsmall holecooling methodultra-deep well
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