Title: Digital Rock Methods for Multiphase Fluid Flows
On 30 January, CSSR hosted the first webinar of the 2026 Open Webinar Series, titled “Digital rock methods for multiphase fluid flows”, presented by Espen Jettestuen. He is a senior researcher at NORCE’s Energy and Technology division and leader of Work Package 1 in CSSR. He holds a PhD in solid-state physics from the University of Oslo.
The recording is now available for those who were unable to attend or would like to revisit the presentation.
Webinar Summary
CSSR Open Webinar Series 2026‑1 featured a presentation by Espen Jettestuen on a digital rock workflow developed within Work Package 1 of the CSSR project. The aim of the workflow is to compute relative permeability and capillary pressure curves from high‑resolution digital rock images, with particular focus on systems subjected to fluctuating flow conditions.
The talk began with an overview of Work Package 1, which studies how time‑varying injections affect reservoir behaviour, spanning scales from pore‑scale simulations to geological characterization. The core of the webinar detailed a workflow that:
- Takes 3D digital rock geometries,
- Performs capillary displacement simulations using a level‑set method,
- Generates two‑phase fluid configurations, and
- Computes flow functions using single‑phase fluid simulation.
Jettestuen compared this approach with direct multiphase lattice‑Boltzmann simulations, noting the latter’s high computational cost and numerical stability issues. The specialized workflow, in contrast, is highly efficient, avoids numerical diffusion, and handles hysteresis more robustly.
A complete example using a high‑porosity sandstone sample illustrated the drainage/imbibition cycles, hysteresis loops, and the resulting flow functions. The team also explored boundary conditions and found that zero‑velocity boundaries performed sufficiently well.
To prepare the results for reservoir‑scale simulators, the group applies an artificial neural network to smooth and generalize the flow functions, including multiple reversal points. The outlook includes validating the method against core‑scale experiments, extending models to three‑phase systems, and improving the treatment of heterogeneity and sample‑size effects—particularly relevant for CO₂ storage, gas production, and hydrogen storage.
For Everyone: What Does This Mean?
In this webinar, Espen presented a new digital method for understanding how fluids flow through rocks deep underground. By using detailed 3D images of real rock samples, the team can simulate how water, gas, or CO₂ move through tiny pores inside the rock. This helps them predict how reservoirs behave when conditions change, such as during CO₂ storage or energy production. The method is faster and more flexible than traditional laboratory experiments and offers new possibilities for studying complex behaviour that is otherwise difficult to observe directly.