A new biogeochemical method for the monitoring of possible seeps in marine CCS fields.
Spagnoli F; Borgognoni L; Campanelli A; Ciceri G; Martinotti V; Giordano P; Giuliani G; Penna P;
The sub-seabed deep saline aquifer CO2 injection for CCS
purposes requires a reliable monitoring of possible CO2 seeps
from the bottom sea. A biogeochemical monitoring method of
CO2 seeps in marine environments has been set up by the
manufacturing of new in situ and laboratory instruments and
their use in the marine environment. The new monitoring
method consists in the determination, before the CO2 geological
storage, of benthic fluxes of dissolved inorganic carbon species
(pCO2 and DIC) and of other connected parameters (alkalinity,
pH and ?13CDIC), in order to characterise the marine carbonate
system, and by investigating the early diagenesis processes, i. e.
the processes originating the benthic fluxes. The knowledge of
the natural benthic fluxes, before the CO2 injection, will allow the
comparison with data obtained after the storage operations so
that possible occurrences of unexpected leakages of the CO2
injected in the geological formations under the sea bottom can
be verified. This method could also be useful employed as an
“early warning” system in case of possible failure of the CO2
storage. For the set up of this biogeochemical monitoring
method two new autonomous and automatic benthic flux
measurement instruments (the Lander AMERIGO and the
Camera Bentica Automatica) and two new laboratory apparatus
for laboratory chemical analysis (pCO2 and DIC analyses) has
been realized. The biogeochemical monitoring approach is
particularly sound in the Northern and Central Adriatic Sea where
numerous previous DIC and other carbonate system chemical
benthic flux measurements and early diagenesis studies have
been carried out, where the new monitoring technology is being
applied and where CO2 sub-seabed storages can be carried out.
Previous researches allowed the definitions of nine different
diagenetic environments in the northern and central Adriatic Sea;
each environments is characterized by: 1) homogeneous
particulate matter and dissolved nutrient continental inputs; 2)
distances from main sediment sources; 3) bottom sediment
composition; 4) organic matter; 5) depths); 6) oxygenation of
water column. In each diagenetic environment a background
value of DIC, alkalinity and pH benthic fluxes has been assigned.
These background values can be used as baseline in the CCS to
monitoring possible seeps after the injection of CO2 in depth. At
present, various researches are in progress in the Adriatic Sea for
the acquisition of new data of DIC and other chemical dissolved
benthic fluxes by the use of the new technology and for the early
diagenesis studies that origin the fluxes.
2013 - Abstract in rivista
Epitome (Udine) 2013 (2013): 1.
Keywords: CCS monitoring