Gassco has been given the task by the Norwegian Oil Directorate to evaluate and design solutions for subsea pipeline transportation of captured CO2 from large CO2 point sources into suitable storage locations on the Norwegian Continental Shelf. As part of the underlying pipeline design work, numerical simulations of the fluid flow have to be undertaken.
In this paper the ability of a selection of pipeline flow simulators to calculate fluid temperatures and pressures during steady-state transport of CO2 has been investigated using different fluid representations.
Commercially available pipeline flow simulators were included in the benchmarking study, and two different simulation cases were defined:
Planned off-shore pipeline from Kårstø to the Utsira formation, operating in the CO2 liquid region
Existing on-shore US pipeline, operating in the CO2 super critical region with steady state measurement data.
The cases were set up and modeled using the different pipeline simulators. Sensitivities were quantified and analyzed, and the results were ranked according to the ability of treating CO2 as a transport fluid.
For case 1, all simulation codes can be used provided an Equation of State (EoS) with appropriate density prediction is chosen.
For case 2, only one simulation code could be used reliably, as all the other tools showed to have problems to calculate the flow accurately when the pipeline conditions approached the critical point of CO2. This commercially available code demonstrated to be able to predict pressure drop and temperature development with high accuracy.
Viscosity is considerably less important but starts to influence frictional pressure drop at lower Reynolds number
Correct prediction of viscosity will be more important in transient simulations, with low fluid velocities
Further study into the effect of accuracy of heat transfer modeling on pressure drop is recommended.
