Study on influence of drilling fluids on temperature distribution over the borehole wall in geothermal wells

Abstract:

In geothermal well drilling, borehole temperatures increase with depths, making drilling more difficult. Therefore, it is necessary to study the circulation temperature distribution in the well. With analysis of the heat conduction process during drilling fluid circulation, and in view of various thermal well parameters in Xiongan New Area, the wellbore temperature control equation is adopted, and the fully implicit finite difference method is used to solve the equation to find the temperature distribution over each well section during drilling fluid circulation in the well. The influence of the drilling fluid density, viscosity and displacement on the wellbore temperature distribution is studied by equation simulation. Results show that the higher the drilling fluid displacement, density or viscosity is, the lower the wall temperature is; and the more the wellbore wall temperature near the bottom decreases. The displacement change of drilling fluid has the greatest influence on the borehole wall temperature distribution. The results of the simulation study provide some reference for the drilling design.

Key words:geothermal wall; drilling fluid; wellbore temperature distribution; discretization; engineering parameter; Xiongan New Area