Determining initial formation temperature considering radial temperature gradient and axial thermal conduction of the wellbore fluid

It is crucial to verify how to accurately determine the initial formation temperature by investigating the heat exchange of wellbore fluid. The heat transfer models of initial formation temperature were established considering the effect of radial temperature gradient and axial thermal conduction, which were solved using the implicit finite difference technique, and the calculated results from two temperature measurement methods, including the cable and measurement while drilling, were compared. Results reveal that fluid radial temperature gradient leads to a change of the initial formation temperature in the upper and lower sections of the wellbore of 0.03 degrees C and 0.32 degrees C, respectively, and the axial thermal conductivity of drilling fluid had little effect on the initial formation temperature. The identical initial formation temperature was calculated from both measurement methods after a long shut-in. Most relevant is that the model results matched actual field data better than other heat transfer models.