Présentations Colloques

Oral Presentation
Session 5.03: CO2 storage in deep saline aquifers and potential impacts on shallow aquifers
Pezard Philippe A.
Small scale gas injection experiments at the Maguelone shallow experimental site (Languedoc, France)
The Maguelone shallow experimental site for shallow CO2 injection (Mediterranean coastline, Gulf of Lions, France) has been developed to compare and integrate surface and in-situ (downhole) hydrogeophysical monitoring methods providing data on the safety and reliability of CO2 geological storage. The presence of two small reservoirs with impermeable boundaries provides an opportunity to develop gas storage experiments at small scale in a saline formation. More in details, the shallow depth of the porous and permeable reservoirs (R1- 13-16 m and R2- 8-9 m) provides an opportunity (i) to test at a reasonable cost a set of geophysical (resistivity, temperature, pressure, SP, seismic and gas measurements), hydrological and geochemical (pH, minor and major cation concentrations) methods, both downhole and at surface with a range of monitoring configurations and in a coordinated manner, (ii) to perform a series of injection under variable conditions (volume duration pressure), (iii) to inject different gases (either neutral such as N2 or reactive such as CO2) to measure and characterize the site response to gas storage, and (iv) to cross-calibrate the different monitoring methods.**Three N2 and three CO2 injection experiments were performed in 2012-2015 as part of the MUSTANG, PANACEA and TRUST FP7 EC projects. During each experiment, the gas plumes were successfully detected by all monitoring techniques. A number of limitations (e.g., subsurface gas leakage, identification of an appropriate baseline in order to exclude the impact of natural phenomena) should to be taken into account. Integrating the lesson learned from these experiments, the next stage is to propose guidelines for CO2 injection, post-injection monitoring and, in perspective, not only to detect and follow the CO2 plume but to quantify the CO2 migration.**