Normalization of Temperature Effect at Geothermal Well Drilling

Abstract

Regulating drilling fluid temperature in drilling deep geothermal wells in many cases becomes the condition that limits not only the effectiveness but the possibility of the drilling itself. The aim of this regulation is to keep the temperature of the drilling fluid within some limits that provide normal conditions for all drilling operations, to normalize the temperature regime in the wellbore. Theoretical study of the heat exchange processes in the wellbore has shown that the temperature distribution in it can be found as the solution of the second order linear differential equation with constant coefficient based on commonly used in mining thermophysics assumptions. Analysis of the factors influencing the temperature has shown that the drill pipe thermal insulating is the most effective means to normalize the temperature regime in the wellbore when drilling fluid flow rate is restricted to small values. As the additional agency the cooling of the drilling fluid at the surface can be considered. Experimental tests of these recommendations carried out at Mutnovsky geothermal field in Kamchatka have shown their efficiency.