Recovery of the Thermal Equilibrium in Deep and Super Deep Wells: Utilization of Measurements While Drilling Data

Abstract

It is shown that in deep and super deep wells the temperature of the drilling fluid (at a given depth) depends on the current vertical depth, on drilling technology (flow rate, well design, fluid properties, penetration rate, etc.), geothermal gradient and thermal properties of the formation. It is demonstrated that minimum field data: records of stabilized outlet mud temperature, several values of bottom-hole mud temperature measured while drilling (MWD) are needed to construct an empirical equation which approximates the downhole temperature profile during drilling. An analytical equation is presented which describes recovery of the thermal equilibrium when the temperature of drilling fluid (at a given depth) is a linear function of time. Calculations of shut-in temperatures for two field examples are also presented.