Analysis of surface drilling fluid cooling combined with insulated drill pipe for wellbore temperature regulation in extra-deep drilling

Abstract:

Ultra-high formation temperature poses a core challenge for extra-deep scientific drilling. To address the bottleneck where existing single cooling technologies fail to meet the temperature control requirements of a 13000 m wellbore， this study employs numerical simulation to evaluate the cooling performance of a combined approach integrating surface drilling fluid cooling and insulated drill pipe， with bottom-hole circulating temperature， maximum wellbore drilling fluid temperature， and return drilling fluid temperature as evaluation indices. The results indicate that applying the combined technology from 11000 to 13000 m can control the bottom-hole circulating temperature， maximum wellbore drilling fluid temperature， and outlet drilling fluid temperature at 285 ℃， 291 ℃， and 63 ℃， respectively. Increasing the application length of insulated drill pipes can effectively reduce wellbore drilling fluid temperatures， and for every 0.1 ℃/100 m decrease in geothermal gradient， the bottom-hole circulating temperature and maximum wellbore drilling fluid temperature both decrease by 9 ℃. This research demonstrates that the combined technology can control key temperature parameters within a safe range for extra-deep drilling operations， providing a crucial theoretical basis for drilling engineering design and site selection， and offering technical support for the successful implementation of extra-deep scientific drilling projects.