Joule–Thomson Effect on Bottom Hole Temperature in Ultra-High-Temperature and High-Pressure Gas Wells

Accurate calculation of temperature and pressure in the borehole of ultrahigh-temperature and high-pressure wells is essential for casing stress analysis. Typically, formation temperature is assumed to be equal to bottom-hole temperature, but this assumption deviates from actual conditions, affecting the accuracy of casing stress calculations. In ultrahigh-temperature and high-pressure environments, the Joule-Thomson effect can cause the bottom-hole temperature to exceed the formation temperature, further impacting temperature calculations throughout the wellbore. This study employs the BWRS equation of state to model the Joule-Thomson effect in ultrahigh-temperature and high-pressure gas wells. A predictive model for bottom-hole temperature in such wells is developed. The influences of production rate, wellbore diameter, and natural gas relative density on bottom-hole temperature are also analyzed. Results show that in these conditions, the bottom-hole temperature decreases as the perforation hole diameter, production rate, and relative density of natural gas increase, due to the Joule-Thomson effect.