CO2 Sequestration
[CO2 leakage rate]
1. When, reported leakage rates from natural CO2 stores
range between a few tonnes
to several hundred thousand tonnes per annum, whether,
the high rates of reported leakage
are all necessarily from tectonically and/or
volcanically active regions only?
Are they no more representative of in-situ geological conditions?
2. Also, whether the intermittent or seasonal-dependent leakage flux,
from the measured flow amounts @ localized gas vents
on a heterogeneous fault zone
would really help in
upscaling measurements
from individual point source leaks
to the entire length of the fault zone?
3. In the case of unpredicted and rapid plume elongation
associated with subsurface CO2 storage,
possibly, resulting from
uncertainty in fluid thermos-physical properties,
poorly imaged topography,
or
centimeter-to-meter scale heterogeneities,
how about the probability of
CO2 migrating beyond the boundaries of the storage complex
for a confined site, particularly, at the start of the operations?
In such cases, how to secure data
on the extent and transmissivity of the connected aquifer and
the presence of any natural gas
(even, if we have data on porosity, permeability contrast, aquifer topology, overall
permeability, injection rate, the length of well over which injection occurs, well orientation
and fluid salinity)?
4. How exactly to address the CO2 leakages
that might start to occur over geological times
(say, after 100 years)?
Or
What happens, when a CO2 plume
reaches an area
in which there is a connected pathway with high permeability,
through the entire thickness of the cap-rock
so that the CO2 leakage occurs on human time-scales?
5. Do we really have a control over the CO2 leakages
caused by increased fluid pressure on critically stressed fractures?
Of course we have very limited control over CO2 leakage and it will find its way slowly back to the atmosphere. A bigger concern for the world is Hydrogen storage and leakage as this will destroy the ozone layer.