CO2 Sequestration: Long Term Effects

Chemical reactions in sandstone reservoirs?

1. In case, if we end up with a ‘significant’ “dissolution” of

both

‘primary silicate mineral’ (anhydrite)

as well as

‘common silicate minerals’ (potassium feldspar and anorthite)

associated with a sandstone reservoir –

following the injection of CO2,

whether, the dissolution morphologies

(associated with the interaction between CO2 fluid and sandstone)

of various sandstone reservoirs (feldspar sandstone; quartz sandstones; dawsonite sandstones; CO2-gas-reservoir sandstones)

deserve a special attention

as a function of reservoir temperature

in the long run?

2. Feasible to ignore the ‘effective diffusivity of CO2’

within the cap-rock –

following the injection of CO2 –

with time –

under all circumstances?

3. Won’t the stresses from the surrounding and

the local seismic disturbances -

try to increase the penetration depth of CO2 diffusion

within the cap-rock -

in the long run?

4. In case, if diffused CO2 reaches

the top most part (the other boundary) of the cap-rock,

could we expect ‘back diffusion’ to happen?

If not, would it become a permanent pathway for CO2 release from its stored site?