Research activity
Geological storage of CO2
The stabilization of the
atmospheric CO2 concentration
requires CO2 emissions to drop
well below current levels. To reach this goal, several available strategies
have been identified, including demand reduction, efficiency improvements, the
use of renewable and nuclear power, and carbon capture and storage (CCS). This
latter consists in capturing CO2
on the spot, at concentrated sources like power stations, cement plants,
refineries, steels mills, etc…, and in storing it in the subsurface where it
will no longer contribute to global warming. Depleted oil and gas reservoirs, unmined coal seams and particularly saline aquifers (deep
underground porous reservoir rocks saturated with brackish water or brine), can
be used for storage of CO2. At
depths below about 800–1000m, supercritical CO2
has a liquid-like density and a gas-like viscosity that provides the potential
for efficient utilization of underground storage space in the pores of
sedimentary rocks.
Please, go to the METSTOR
website ( www.metstor.fr
) for more information.
Chemo-hydro-mechanical
analysis of wellbore cements under supercritical CO2 attack
Publications (preprint)
Figure 2
: Evolution of the AC and HC sample carbonation front versus the square root
of carbonation time. |
After being
injected into a deep saline aquifer or into a depleted oil/gas reservoir, the
CO2 plume should encounter abandoned wells, which are cemented
with conventional cements. Thus, although the CO2
injection well will be rather cemented with a cement resistant for CO2, the resistance of the cement
used for existing oil and gas wells is of main interest for the safety
assessment analysis of the CO2
geological storage. The interaction
between carbon dioxide and Portland cement mainly consists in the chemical
reaction of its calcium bearing mineral, which are mainly Portlandite (CH)
and Hydrated Calcium Silicate (C-S-H), with the carbon dioxide resulting of
the initial matrix leaching, and the formation of calcium carbonates and
water. Its consequences at atmospheric pressure and temperature conditions
are a relatively well-known. However, under downhole temperature and pressure
conditions, the interaction between cement and wet supercritical CO2
(wet scCO2) and/or CO2 dissolved in water is
drastically fasten up. The kind of minerals that is dissolved or precipitate
may change and the overall mechanical behaviour is expected to change
significantly. Under these
considerations, my research activities on this subject are to investigate,
experimentally and theoretically, the influence of the carbonation under
downhole condition on the wellbore cement behaviour. |
Related topic: Effect of the salt
crystallization on the hydro-mechanical behavior of the reservoir rock (PhD
Thesis of Florian Osselin).
Capture
and Storage of CO2 issued from biomass
Publications
(preprint)
Figure
1: CO2 balance of the Biomass-CCS system studied in the context of the CPER Artenay project. A:
capture and storage of both CO2 from biomass and from the natural gas power
plant and B: capture and storage of the CO2 from the fermentation process
alone. |
Capture and storage of CO2 from fossil fuel combustion is gaining attraction
as a mean to tackle climate change. This technology can contribute to a large
reduction of the atmospheric greenhouse gases (GHG)
concentration. In this study, we are dealing with a variant CCS system where
the stored CO2 comes from
biomass instead of fossil fuels. Several industrial sectors could be
investigated like the paper industry, the electric sector, or the biofuel sector.
According to (Kheshgi and Prince, Energy,
2005), this last option called BCCS
(Biomass & Carbon Capture and Storage) may be considered as a relatively
cheap solution, in favourable conditions, which can potentially contribute to
a net GHG emission reduction, seeing that CO2
from biomass is considered neutral. Moreover, although the amount of CO2
that is emitted by most biofuel distilleries is small (about hundred times
lower than steel mills for example), the IEA CCS
Roadmap (2009), emphasizes that this system has the global potential to store
about 2 Gt of CO2 by 2050, assuming that
biofuels account for 26% of the total transport fuel demand (BLUE map
scenario). Based on
these qualitative observations, the CPER Artenay project presents a real case study to quantify
the environmental benefits and the technico-economic
feasibility of the application of BCCS systems in
the biofuel sector. |