22-27 September 2019
Trade Fairs and Congress Center (FYCMA)
Europe/Madrid timezone

Aquifer Dynamic Characterization Tools System : the ADYCHATS industrial pilot site for better understanding of mass flux in groundwater

26 Sep 2019, 15:00
15m
Multiuse room 3 ()

Multiuse room 3

Oral Topic 5.1 - Dynamic Analogues Parallel

Speaker

Dr Beatrice Ducastel (TOTAL SA)

Description

In the TOTAL R&D Program on Environmental and Societal Stakes, ‘Soil and Groundwater’ is one of the primary environmental compartments of interest to better characterize and monitor for long-term and sustainable exploration, production, refining, manufacturing and services operations. Over the last few years, studies have been dedicated to creating a research and development platform to address the challenges of shallow and deep groundwater dynamic characterization and monitoring on industrial sites. The ADYCHATS industrial pilot (standing for Aquifer DYnamic CHAracterization Tools System) was launched in 2018 on a 6-ha experimental area of TOTAL R&D Lacq Research Center (PERL), within the historical industrial platform of Lacq in the southwest of France. The alluvial geology of the shallow unconfined aquifer is primarily comprised by unconsolidated coarse gravel deposited by the Gave de Pau (river of Pau) with spatially discontinuous interbeds of sandy and loamy gravels. Currently, 20 piezometers have been installed to an average depth of 6 meters and operate permanent or punctual probes for classical temperature, pressure, and conductivity measurements. Periodic exhaustive surveys are being performed several times per year to measure the physical and chemical parameters of the groundwater at the time of, or shortly after, sampling. Innovative tools have been also deployed to measure groundwater velocity. Multi-level Point Velocity Probes (PVPs) containing two probes per stand have been installed directly in the unconsolidated porous media to measure the groundwater pore-water velocity at five locations and two depths, corresponding to two distinct hydrostratigraphic facies. The first results of PVP measurements showed measurements of direction consistent with the global piezometric map of the site. These measurements reveal structural heterogeneities at or below the meter scale that have to be taken into account for a better understanding of preferential pathway for potential solute transport in groundwater. In parallel, In-Well Point Velocity Probes (IWPVP) have also been deployed in piezometers to estimate the Darcy velocity, direction and magnitude, in the surrounding aquifer and further validate the PVP measurement results. PVPs directly measure the porewater velocity but require dedicated boreholes that collapse against the probe. IWPVPs are multi-use instruments that can be installed and removed from monitoring wells. However, the IWPVP measures a groundwater velocity through a probe seated within the well screen which must then be calibrated to estimate the Darcy velocity within the surrounding media (or porewater velocity correcting for the effective porosity). In the future, near simultaneous groundwater velocity measurements will be conducted. The final aim of the studies performed on ADYCHATS pilot is to provide an in-situ, real time, continuous and cost-effective network of tools and methods for dynamic characterization and monitoring of groundwater flow and mass flux.

Primary authors

Dr Anthony Credoz (TOTAL SA) Dr Beatrice Ducastel (TOTAL SA) Mrs Nathalie Nief (TOTAL SA) Mr Trevor Osorno (University of Kansas) Dr John Frederick Devlin (University of Kansas) Mr Salvador Jordana (Amphos 21) Dr Marti Bayer Raich (Amphos21)

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