In the Paris agreement, countries agreed to limit the rise in global temperature by 2 degrees. One of the means to do so, is by technologies that capture and store CO2 deep underground, preventing its release into the atmosphere. To support these methods, robust and accurate modelling capabilities are needed, in particular to simulate CO2 flows in pipelines and wells. In a new project, CWI and Shell are joining forces to tackle this challenge, by appointing a PhD student to work on this topic for the coming four years.
Before storing CO2 under the ground, the gas has to be separated from other gases produced by large power stations or industrial plants and transported through pipelines. To be able to optimize this transport, mathematics is used to model and simulate it. A main difficulty in the models arises from phase transitions (for instance, from gas to fluid) and from a sensitivity to contaminations (impurities).
Benjamin Sanderse, head of CWI's Scientific Computing research group, explains: “When transporting CO2, it is typically not in a gaseous or liquid phase, but in an intermediate state known as ‘dense phase’. When this CO2 in dense phase is injected and stored in an underground reservoir, the pressure and temperature change, and the dense phase can change into a mixture of liquid and gas, just like you have in your favourite bubble drink. Such multiphase flows are hard to predict.”
At CWI, the PhD student in this project will develop and improve advanced mathematical methods for better simulations. In detail, she or he will derive a novel discretization scheme for the conservation equations that govern the flow of CO2 in pipelines. An important challenge is that it has to be able to cope with the fast phase transitions in CO2, by a reformulation of the energy equation in terms of pressure and enthalpy. Furthermore, new discretization techniques will be developed that are able to deal with narrow ‘phase envelopes’, addressing the stiffness induced by fast phase transition.
The project ‘Robust numerical modelling for transient multiphase CO2 transport’ is part of an ongoing CWI-Shell collaboration, continuing earlier projects on digital twins for leak detection and on discretization methods for slug capturing in two-phase flow. The current project is financed by Shell (at the Energy Transition Campus Amsterdam), will run for four years, and will be carried out in the Scientific Computing group at CWI.
Main photo: Reducing CO2 emissions by optimizing carbon capture, utilization and storage (CCUS) requires new mathematical modelling techniques, like the ones that will be developed by CWI in collaboration with Shell. Picture source: Alberta Carbon Trunk Line, by Wolf Midstream/North American Energy Pipelines.
