Objective The temperature of the drilling fluid has great significance of the selection of drilling tool feed and steering tools. In order to effectively guide the horizontal drilling process of deep shale gas and obtain accurate temperature distribution throughout the well section of the drilling process, deep drilling temperature field research has been carried out.
Methods A model was established with energy conservation and thermal resistance methods. The flow heat transfer model used the finite difference method to calculate the temperature profile of the entire well during the drilling process, and accurately predicted the temperature field of the drilling fluid during the drilling process with an error of less than 5%. The effects of drilling fluid flow, inlet temperature and circulation time on wellbore temperature distribution are analyzed.
Results The overall temperature of the drilling fluid in the circulation process decreased with the increase of the circulation time. Increasing the circulation flow of the drilling fluid can effectively reduce the temperature in the wellbore. The flow rate increased from 8 t/h to 16 t/h, and the bottom hole temperature reduced by 10 ℃. The inlet temperature had little effect on the long horizontal section of deep drilling. The inlet temperature changed by 20 ℃, and the bottom hole temperature only changed by 3 ℃.
Conclusion The methods of extending the circulation time and increasing the flow of circulating drilling fluid can significantly improve the cooling effect of the drilling process.
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