Realisticity of the biomineralization exercise
In the discussion on the use of the new CO2 tables (see !124 (merged)) for the biomineralization exercise in the dumux-course, we were reminded that the biomineralization exercise is not 100% realistic or physical.
Problem:
In the setup, the depth is only a few meters deep, but still CO2 is injected, which realistically would only be injected at supercritical conditions (much deeper => hydrostatic pressure > CO2 critical pressure. Thus, the example is somewhat unrealistic. However, the CO2 injection is not the main focus of the exercise, so having a realistic CO2-injection scenario at the end might not be a top priority. The CO2 injection mainly serves to visualize the effects of biomineralization on the leakage due to permeability (and porosity) reduction, and for this purpose, gaseous CO2 might even be better than supercritical CO2 due to its low density and, thus, high buoyancy.
Remedies:
I would propose three possible remedies:
- Increase the depth of the setup to realistic depths (hydrostatic pressure > CO2 critical pressure), prefereably with a safety margin => e.g. 1km instead of a few m. this would then also require to use CO2 tables with sufficient maximum pressure value.
- Using a different fluid/gas for the injection or even reframing in terms of leakage would also be an option to increase the realisticity. However, this would require to add a component to the fluid system, making the system (+ system of equations) more complex (and slower to solve), which might be a drawback in an exercise. CO2 (or rather total inorganic carbon) is anyway already an integral component of the biomineralization system and therefore using CO2 as a gas injected to visualize the effects of mineral precipitation is basically a "free lunch".
- Alternatively, live with the questionable "realisticity / meaningfulness" of the setup, but there should be an acknowledgement of it in the exercise's readme. This might be a sufficient solution as the CO2-injection is not the main focus of the exercise.