CO2 Sequestration [CO2 Transport]
1. With transport of CO2 in brine solution under fully saturated conditions;
(A) Can we characterize the diffusion of the dissolved CO2 species by the solubility of CO2 in brine solution by Henry’s law and caused by a concentration gradient in the pore fluid pressure by Fick’s law?
(B) Can we characterize advection in the liquid phase to be driven by a pressure gradient in the brine solution by Darcy’s law?
2. Which one of the following parameters predominantly affects CO2 transport in brine solution?
(A) The solubility of the CO2 species
(B) The aqueous diffusion coefficient of CO2
(C) The porosity and tortuosity of the aquifer/reservoir
(D) The permeability of aquifer/reservoir.
3. When characterizing the visco-capillary two-phase flow, following the invasion of CO2 into a brine-filled aquifer as a separate phase, how exactly CO2 enter the pore network?
(A) CO2 has to displace the brine solution under the complex interactions of gravity, viscous forces and capillary effects (instable invasion)
(B) As an immiscible displacement of the brine solution front (stable propagation)
4. What exactly controls the mobility of CO2, upon exceeding the CO2 entry pressure (the capillary threshold pressure, a gas must exceed for it to be transported into a brine-saturated solution)?
(A) The intrinsic permeability of aquifer/reservoir
(B) The relative permeabilities to CO2 and brine depending on the saturation (relative permeability curves)
(C) The variation of the capillary pressure with saturation (brine retention curve)
5. Can we expect dilatancy-controlled CO2 flow (which depends on the state of deformation of aquifer) in the absence of visco-capillary two-phase flow?
Since, there will be no transport of CO2 until a significant CO2 gets build-up, can such cases be considered as CO2 trapping?
During such CO2 trapping, won’t it lead to localized consolidation of aquifer rock materials?
Can it withstand long-term CO2 pressures with a magnitude greater than the minimum principal stress acting on the rock mass?
Won’t such build-up CO2 pressures lead to the creation of additional porosity in the form of micro-fractures – leading to the development of least resistive pathways, through which CO2 could escape with ease?
6. Can we expect CO2 transport by macroscopic fracturing, when the coupled effect of brine solution displacement and formation of small-scale fractures remains to be no more sufficient to counterbalance the continued CO2 pressure build-up under high CO2 injection rates?
7. What would happen upon the development of a macroscopic tensile fracture, when CO2 pressure exceeds the sum of the minimum principal stress and the tensile strength of the aquifer rock?
Suresh Kumar Govindarajan
Professor (HAG) IIT-Madras
https://home.iitm.ac.in/gskumar/
https://iitm.irins.org/profile/61643
25-July-2024
- Badges
- Science method
- Similar topics
- Methodology
- Crystallography
- X-ray Diffraction