Table 1 Results of the sensitivity study.

LHFZ, thickness of HFZ; LNBZ, thickness of NBZ; dPI, distance between the seafloor and the front of the CO2 plume at the end of the injection; dmin, minimum distance between the seafloor and the front of the CO2 plume; Td, time spent for the CO2 plume to reach the minimum distance; dHFZ, distance between the front of the CO2 plume and the base of HFZ at Td; dup, distance of upward migration of the CO2 plume after injection ceases.

ParametersValueLHFZ (m)LNBZ (m)dPI (m)dmin (m)Td (years)dHFZ (m)dup (m)
Ocean depth (m)1000252287292742223258
20002952931074698188186
3500*3442252992813636318
Vertical permeability (mD)10*3442252992813636318
503442252992512679348
10034422529322727211766
Vertical permeability (mD) with ocean depth = 1000 m10252287292742223258
502522570189252257
100252227089252227
Geothermal gradient (K/m)0.03*3442252992813636318
0.0425915329923310382666
0.052061162991979709102
Seafloor temperature (°C)3*3442252992813636318
43151782992697714630
52801312992578182342
Carman-Kozeny factor3*3442252992813636318
5344225299292235527
734422529929879461
Porosity0.153442252812632688118
0.25*3442252992813636318
0.353442253112933945118
Injection depth (mbsf)35034422525123934410512
400*3442252992813636318
5003442254013351150966
Injection rate (metric tons/day)750*3442252992813636318
15003442252752516739324
225034422525723359511124
Injection time (years)10*3442252992813636318
5034422523320954313524
100344225191161100918330
Injection temperature (°C)15*3442252992813636318
203442252992754736924
253442252992696037530

*Base case.

†For the case of changing vertical permeability, the ratio of horizontal permeability to vertical permeability remains the same (5:1) to ensure the same anisotropy.