Smeaheia Pressure increase after injection wells are closed off

[flammmes]

So I have been trying to run the Smeaheia Gassnova dataset in flow and I have noticed this behavior.

The pseudo brine producers close around 2060 and pressure expectedly increases more rapidly since injection stops at 2070. However, once injection stops, pressure keeps increasing in a logarithmic profile up until 2200. Furthermore, it keeps slightly increasing up to 2450 despite expecting a slight drop due to convection.

What could explain such behaviour? I've tried reducing and increasing the rates, stoping injection earlier or at the same time as brine production but still pressure seems to keep increasing. I should possibly mention that initial reservoir pressure is at 150 bar and my case starts after restarting from the base case in 2022 but I don't think this is relevant.

Keep in mind that I am using 2024.04 due to issue I have encountered with Restart files in later versions.

Gassnova.zip

[Alv-Arne]

If some of the the injected CO2 is still mobile in 2060, which I believe will be the case, there will be an overall shift of the CO2 distribution to shallower depths. Since the pressure and thus CO2 density decreases with shallower depth, it will displace more water, which could explain the overall pressure increase that you notice. On the longer term, as more CO2 dissolves (if you have this option turned on), the pressure will start to decline.
Perhaps you could make a 'free gas in place' vs. depth plot to investigate this further. Or look at the reservoir volume of free CO2, if this is reported somewhere.