CO2 Sequestration – Capillary Trapping

1.  Whether the way CO2 gets displaced by the resident fluid – following its injection – would remain to be the same (a) laboratory-scale; (b) pilot-scale; and @ (c) field-scale?

If not, whether the way CO2 gets migrated - in response to buoyant forces and pressure gradients - for the above 3 cases – would remain to be different?

2.  Feasible to capture the way, the tiny isolated blobs of CO2 – getting trapped by capillary forces, when the aquifer/reservoir brine imbibes back into the pore-space (following the migrating of CO2 plume)?

Do we have laboratory/field-luxury that captures the way, the interfacial forces remains controlled @ such micron-scales?

In such cases, where, CO2 plume migration gets evolved with the immobilization of CO2 blobs, then, to what extent, will we be able to precisely estimate the CO2 storage capacity; and in turn, it’s associated, CO2 storage security, which requires, explicit details on (a) ‘the extent of CO2 trapping’; and (b) ‘the rate of CO2 trapping’?

Feasible to ensure, the existence and stability of residually trapped CO2, either @ laboratory or @ pilot-scale?

3.  Is there a way, to ensure that the injected CO2 preferentially gets filled only through a relatively larger pore-sizes of the concerned aquifer/reservoir, and thereby initiating the resident brine to be held in relatively smaller pores – when CO2 starts invading the pore space as the non-wetting phase?

In such cases, would it remain feasible - to precisely distinguish between (a) the wetting layer regime (where the resident brine clings to the corners and roughness of the pore space, which enhances CO2 trapping through snap-off) and (a) the frontal advance regime (that suppresses CO2 trapping) – in order to estimate the resultant amount of ‘capillary trapping’?

Whether snap-off could still occur, if the migration of the resident-brine remains only marginally impeded - by the relatively larger pores?

In the absence of sufficient data on (a) pore-sizes; (b) pore-size distribution (in particular, the ratio of pore to throat size); (c) CO2/brine flow rates (the hydraulic connectivity); and (d) the contact angle between CO2 and solid surface (wettability), can we still justify the estimation of resultant capillary trapping?

4.  To what extent, Land’s IR (Initial-Residual) Model would remain to be relevant, when only a relatively smaller fraction of pores remains filled with CO2, ‘initially’ (which essentially curtails the snap-off and trapping, upon the invasion of brines into the pore spaces)?

5.  If we have a dynamic wetting-state of a CO2-brine system, then, can we still consider (a) IR characteristics of an aquifer; (a) capillary pressure and (a) relative permeability – of such systems – to remain to be ‘invariant’ for a wide range of CO2/brine saturations; as well as, under a wide range of aquifer pressure, temperature and brine salinity conditions?