European training Network for In situ imaGing of dynaMic processes in heterogeneous subsurfAce environments

Project Information

ENIGMA

Grant agreement ID: 722028

DOI

10.3030/722028

Project closed

EC signature date 16 August 2016

Start date 1 January 2017

End date 31 January 2021

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 3 865 769,64

EU contribution

€ 3 865 769,64

Coordinated by

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
France

Periodic Reporting for period 2 - ENIGMA (European training Network for In situ imaGing of dynaMic processes in heterogeneous subsurfAce environments)

Reporting period: 2019-01-01 to 2021-01-31

Summary of the context and overall objectives of the project

The ENIGMA network trains a new generation of young researchers in the development of innovative sensors, field survey techniques and inverse modelling approaches.
This contributes to enhance our ability to understand and monitor dynamic subsurface processes that are key to the protection and sustainable use of water resources.
ENIGMA focuses mainly on critical zone observation, but the anticipated technological developments and scientific findings will also contribute to monitor and model the environmental footprint of an increasing range of subsurface activities, including large-scale water abstraction and storage, enhanced geothermal systems and subsurface waste and carbon storage.
ENIGMA gathers (i) world-leading academic teams and emerging companies that develop innovative sensors and hydrogeophysical inversion methods, (ii) experts in subsurface process upscaling and modelling, and (iii) highly instrumented field infrastructures for in-situ experimentation and validation.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Two years after the beginning of the Enigma ITN project, four workshops were organized and all ESRs participated to the 4th Enigma Cargèse Summer School in Cargèse, 25 June – 7 July 2018, where they presented a poster.
All the dissemination documents (presentations and posters) of the ESRs are available on their personal webpages on the Enigma website : https://enigma-itn.eu/people/research-fellows/
Some details about the work performed:

WP2: Explore coupled dynamic processes in targeted highly instrumented sites
• Scientific objective 2: explore in-situ flow, transport and reaction processes to address current open scientific questions based on highly instrumented experimental sites where the new results, data and open source codes
- ESR1 did numerical modelling on the impact of heterogeneity and connectivity on mixing and reactions in coastal aquifers
- ESR2 carried out high resolution time-series analysis of ground water levels and different tracer tests in the riparian aquifer of the Selke River
- ESR3 : three in-stream piezometers were installed in the Emme site for dissolved gas relative concentrations analysis.
- ESR4 completed two experiments at the SKB Äspö tunnel Hard Rock Laboratory.
• Technological objective 2: transfer the obtained knowledge of process dynamics in heterogeneous porous and fractured media to operational models for predicting the evolution of subsurface environments.
- ESR2 worked on a numerical flow model in HGS.
- ESR3 learnt how to use: HydroGeoSphere and OpenFOAM (CFD code) multi-phase solvers interFoam (IF).
- ESR4 created a 3D statistical Discrete Fracture Network (DFN).

WP3: Quantify temporal changes in subsurface water content and fluxes distributions
● Scientific objective 1: design novel in situ experimental strategies for quantifying subsurface process dynamics by coupling innovative experimental methods and inverse modelling approaches
- ESR5 tested rock physic models to infer their ability to describe VP and Vs seismic data acquired during experiments at Ploemeur hydrogeological observatory.
- ESR6 developed a new model to describe temperature profile in boreholes, dedicated to the high resolution measurement ability of Distributed Temperature Sensing (DTS) data.
- ESR7 monitored thermal dynamics in the subsurface using fiber optic distributed temperature (FO-DTS) sensing and thermal infrared (TIR) images from drone flights for the top part of the media and temperature profiling in boreholes for the groundwater temperature.
- ESR8 carried out monthly vertical gravity gradient survey with a relative gravimeter out at the geodetic observatory in Karstic environment on the Larzac Plateau, France.
●Technological objective 1: develop and validate innovative environmental sensing techniques with the required sensitivity, as well as spatial and temporal resolution to monitor dynamic processes
- ESR5 designed and carried out a controlled infiltration experiment using injected water and geophysical measurements at the Ploemeur site in France.
- ESR6 designed a framework for real time flow profiling in a wellbore using DTS temperature data to analyze fracture.
- ESR7 used combination of FO-DTS and TIR imaging for the upper part of the media in combination with the profiling in boreholes to have insights on the groundwater upwelling processes occurring on land.
- ESR8 developed survey protocols to monitor vertical gravity gradients for hydrological signal detection. The development and coupling of a hydrological model for the site with a gravity forward routine has been conducted for joint analysis. The operability and sensitivity at the level of 10nm.s−2 have been shown by Muquans in a publication this year (Ménoret et al., 2018).

WP4: Create new methods for tracking the transport and reactivity of chemical species in subsurface
•Scientific objective 1:
- ESR9 : Electrical Resistivity Tomography (ERT) :The relationship between the conductive phase distribution and the effective electrical conductivity is being investigated both theoretically and experimentally for a simple case of a 2-D layered medium.
- ESR10 carried out numerical study of time-lapse GPR full-waveform inversion to detect tracer plumes. GPR-FWI was tested for its potential to detect tracer plumes and to better plan the experimental setup. Detailed hydrogeological model was generated based on past measurements.
- ESR11 explored the roles of parameter uncertainty and spatial heterogeneity using Monte-Carlo simulations.
- ESR12 performed a soil column experiment with induced calcite precipitation in collaboration with Yuxin Wu of the Lawrence Berkeley National Laboratory in the United States.
•Technological objective 1:
- ESR9 performed conservative fluorescent tracer tests in the laboratory using the coupling of a 2-D millifluidic setup equipped with a fluorimetric setup, and a geoelectrical monitoring setup
- ESR11: An innovative multi tracer experiment using jointly a dye tracer, heat and a dissolved gas cocktail, (He-Xe) was performed in a chalk aquifer nearby Mons, Belgium.
- ESR12 developed a novel laboratory setup combining a millifluidic-cell and an SIP measurement system to quantitatively investigate SIP response and biochemical reactions.

WP5: Design inverse modelling strategies for dynamic processes in complex subsurface structures
•Scientific objective 1:
- ESR13 developed a modeling and inversion framework for monitoring solute tracer tests with the help of geoelectrical monitoring. Field experiments were conducted at the hydrogeological test site Lauswiesen.
- ESR14 conducted time-lapse cross-hole electrical resistivity tomography (CHERT) in the Argentona experimental site. The experiment captured short-term and long-term salinization events in the coastal aquifer.
- ESR15 proposed a probabilistic inversion framework to integrate realistic prior information on structure. A paper entitled “Updating structural uncertainty using features of geophysical data” is in preparation.
•Technological objective 2:
- ESR15 explored Bayesian evidential learning (BEL) as a method to integrate flow and transport simulations and geophysical forward models.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

ENIGMA will foster EU and international cooperation in the water area by creating new links between hydrogeological observatories, academic research groups, innovative industries and water managers for high-level scientific and professional training.

ENIGMA ITN Topics and methods