Over the years, physical tests have been pivotal in evaluating the thermal performance of subsea Oil and Gas production systems. However, the substantial costs associated with these tests have consistently driven efforts towards more cost-effective alternatives. Consequently, numerical modeling has become an indispensable tool in the subsea oil and gas production sector.
A prevalent challenge in this field revolves around the risk of hydrate formation within subsea production systems (SPS) exposed to low temperature and high pressure. While Computational Fluid Dynamics (CFD) offers insights into production fluid cooling within the SPS, it remains computationally expensive. Conversely, Finite Element Analysis (FEA) lacks the ability to solve fluid movement, rendering it impractical for this purpose.
This paper introduces an innovative 'iterative-FEA' approach aimed at maintaining the accuracy of SPS cool-down simulations, typical for CFD, while significantly reducing calculation time to a level akin to FEA modeling.
To assess this method's effectiveness, the authors modeled flow system test cases using both CFD and iFEA methods. The CFD models were solved using Ansys Fluent, while iFEA simulations were conducted with the Ansys Thermal module alongside a set of original APDL scripts.
To validate the computational results, a full-scale experimental rig was constructed, incorporating a dummy SPS section immersed in a water container and equipped with a comprehensive data measurement and acquisition system. The rig simulated the system's operation and underwent experimental testing using three distinct working fluids: water, air, and diesel oil.
In analyzing the dynamics of fluid temperature change, the iFEA simulation results aligned with the experimental data as accurately as the CFD cases but within significantly shorter simulation times. This achievement represents a breakthrough in industrial SPS thermal simulations.