Research on Wellbore Temperature Control Method of Water-Based Drilling Fluid

When developing deep oil and gas reservoirs, the high temperature environment at the well bottom restricts the drilling efficiency to a great extent. Therefore, based on the energy conservation equation, the temperature gradient equation of the fluid in the wellbore is derived. The fourth-order Runge–Kutta algorithm is used to solve the model in this paper, and the sensitivity analysis of the temperature distribution law of the annulus fluid is carried out. The results show that the specific heat capacity and the thermal conductivity of drilling fluid are the main factors affecting the annulus temperature profile. Therefore, a borehole cooling technology based on nanoparticles to improve the thermal conductivity of drilling fluid is proposed. Subsequently, the cooling effects of various nanoparticles were compared, and it was found that the Nano Cu particles with a concentration of 9 wt% had the best cooling effect on the borehole, and the cooling effect gradually increased with the increase of the circulation time. The research results can provide a theoretical basis for controlling the borehole temperature of ultra-deep well and geothermal well and reducing the wellbore complex accidents caused by high temperature.