Research on wellbore temperature control and heat extraction methods while drilling in high-temperature wells

During the drilling process, the downhole high-temperature problem has considerably limited the exploration and development of deep oil and gas reservoirs and geothermal resources in China. The aim of its oil and gas exploration and development has gradually shifted to deeper formations. In this study, a transient heat transfer model for high-temperature wells during the drilling process is built. Both heat sources and variations of thermophysical properties of drilling fluids and tubular string with temperature and pressure are considered. An iterative method is used to calculate annular temperature distributions by considering fluid composition, complex casing programs combination, and well structure.Based on the model in this study, a heat extraction-while-drilling technology approach is proposed by combining insulated pipe string and the phase-change heat storage drilling liquid. The results show that this method effectively reduces the bottom-hole temperature while using the geothermal energy of high-temperature wells. The study's results provide a theoretical foundation and technical support for resolving downhole high-temperature complications in deep oil and gas, as well as geothermal well drilling. The results will be a helpful supplement for the petroleum industry in achieving the national energy aim of carbon neutrality and peak carbon dioxide emissions.