The current cases demonstrate the data set up to perform simulations capturing gas production in a reservoir followed by CO2 injection. Due to the extra chemical components required, the multiphase flow model used in Pflotran-OGS will differ from the models used in the previous cases. The simulations will consider 5 stages with the following set up:

 

1.Initialisation:

i.A hydrostatic pressure distribution

ii.Surface temperature of 10 ºC with a thermal gradient of 0.035 ºC / m

iii.Uniaxial stress burial conditions derived from the sediment column weight

 

2.Gas depletion:

i.Methane gas production will be simulated from t=1 year to t= 21 years (20 years of production)

ii.Production via a well located in a corner of the reservoir from depth of 1370 m to 1390 m

iii.A depletion target gas surface volume rate of 0.1 Mt/year (0.025 Mt/year for the quarter-model)

 

3.Post depletion

i.Period of 4 years ( from t=21 year to t= 25 years) after methane production ceased which precludes CO2 injection

 

4.Injection:

i.Injection of CO2 will be simulated from t=25 year to t= 45 years (20 years of injection)

ii.The injection is performed in the same well that was used to produce methane

iii.An injection target gas surface volume rate of 1.0 Mt/year (0.25 Mt/year for the quarter-model)

 

5.Post-Injection:

i.After injection the well is closed and the simulation is carried on for 5 extra years after well closure

 

 

Two cases using different flow modes will be considered:

 

▪Case02a: COMP3 multi-gas component mode (Gas/Solvent/Water)

 

▪Case02b: COMP multi-component mode

 

The user is assumed to be familiar with Case01 before undertaking the above two cases.