Safety and Thermal Analysis of CO2 Injection Pipeline During Electromagnetic Induction Heating

The transportation of CO2 used for CO2 enhanced oil recovery (EOR) is typically done through pipeline or truck. Pipeline transportation is usually in dense phase, and it is suitable for well groups that are accessible to the pipeline. Truck transportation is generally for remote single wells. The temperature of injected CO2 from the tank is relatively low, generally between −15 ℃ and −20 ℃. During the process of alternating gas and water injection, the pipeline can easily become blocked due to water freezing if it is not preheated. Currently, modular skid-mounted equipment is widely used for injection, and electromagnetic heating is the preferred method for pipeline heating due to its small size and high efficiency. Electromagnetic heating is based on the principle of electromagnetic induction for energy conversion. In this heating mode, the coil directly surrounds the pipeline conveying CO2 for heating. Through electromagnetic induction, the heated pipe wall conducts heat energy to the CO2 in the pipeline, increasing its temperature to the design temperature. As the CO2 pipeline is a high-pressure pipeline, studying the stress state change during the heating process is a prerequisite for the design and usage of electromagnetic heaters. In this paper, theoretical and experimental analyses were conducted on the heating process of high-pressure CO2 transport pipelines using coil-wound electromagnetic induction heaters. The stresses on the pipeline during the heating process were analyzed using fluid-solid-magnetic-thermal coupling analysis. Based on finite element calculation methods, the temperature profile of the heating pipeline and CO2 fluid was obtained, and the surface temperature and radial temperature difference of the pipeline were evaluated. The effectiveness of the heating process was analyzed from multiple perspectives, such as eddy current distribution, temperature distribution, preheating time, and heating performance. The critical conditions for local hot spots caused by uneven temperature distribution were discussed. Through extreme load testing of pipeline heating, the reasons for pipeline failure were verified, and the key points for heating design were summarized.