Modelling and Verification of Transient Flow and Heat Transfer for CO₂ Injection Wells — Application to CCUS Project at H3 Block, China

The growing urgency to mitigate global warming has accelerated the development of carbon capture, utilization, and storage (CCUS) technologies, including promising field CO₂ injection techniques. In the H3 block of China, a large-scale CO₂ injection project was implemented for CCUS-EOR. This study focuses on creating a CO₂ wellbore flow and heat transfer calculation model for on-site construction guidance. The model utilized the Span-Wagner equation for CO₂'s unique physical properties and integrated fundamental principles like mass conservation, momentum theorem and energy conservation. Using the finite difference and iterative solving methods, a prediction model for transient temperature and pressure in the CO₂ injection wellbore was developed. Verification against on-site measurements showed less than 3% error in pressure and a 5% error in temperature. It was observed that increasing the injection rates led to variations in wellbore pressure and temperature due to the increased frictional pressure drop and enhanced heat transfer between the fluid and the wellbore. Since the physical properties of the fluid and its flow and heat transfer processes within the wellbore influence each other, adopting a temperature-pressure coupled calculation model can effectively improve computational accuracy.