Study on prediction of annular trap pressure in ultra-high temperature and high pressure gas wells

Accurate calculation of annular trap pressure in ultra-high-temperature and high-pressure (UHTHP) wells is crucial for ensuring the safety and integrity of tubular systems. Existing annular pressure prediction models often fall short due to inadequate consideration of key factors, resulting in reduced accuracy and, consequently, unreliable predictions for tubular safety assessments. This paper examines the underlying mechanisms of annular trap pressure in UHTHP wells and proposes a multi-annular pressure prediction model grounded in the compatibility principle. A gas-liquid two-phase multi-annular pressure coupling model is also developed, incorporating nitrogen injection into the A annulus and utilizing the BWSR equation of state to enhance the modelʼs accuracy. Additionally, a pressure prediction model for the annular space between dual packers is introduced, building upon the multi-annular pressure prediction framework. The results demonstrate that the proposed multi-annular pressure model significantly improves the accuracy of APB predictions for UHTHP gas wells. The findings provide valuable theoretical insights and practical guidance, facilitating more precise prediction of annular trap pressure in extreme downhole conditions and offering essential support for safe operations in these challenging environments.