The CMG STAR foam model is an empirical model where the effect of gas blockage in high-permeability channels is simulated by simply decreasing the gas relative permeability. It does not represent the actual physics, but similar to other EOR simulations, the gas relative permeability is adjusted as described above.

In our laboratory experiments, we attempted to model foam flooding results using the CMG STAR model. The model produced endpoint gas relative permeability values in the range of 10⁻² to 10⁻³, which appear very low. However, these values are supported by a significant increase in pressure drop across the core sample at a constant injection rate.

We reviewed the literature to determine whether other parameters should be adjusted to achieve a better match while keeping the endpoint gas relative permeability slightly higher. We found only 1-2 papers, and they also have predicted the same ultra low rel perm of gas in foam flood. ( attached figure 10 of the following paper).

Article Estimation of Local Equilibrium Model Parameters for Simulat...

It seems this should work, but reported data is very less and thus causing some uncertanity in history match obtained this way.

I am not sure weather results are common, and that the very low gas endpoint permeability predicted by CMG STAR can still model foam behavior accurately at the core, pilot, or even field scale.

At first glance, the concept makes sense—if gas blockage is considered, the gas relative permeability should indeed approach very low values. However, I am still uncertain about using ultra-low relative permeability values in simulations.

I am unsure we should change something else in our model to get a good history match or should proceed with the predicted value.