Topographically-driven fresh groundwater flow in offshore carbonate platforms.

Project Information

OFF-GROUND

Grant agreement ID: 101038076

DOI

10.3030/101038076

Project closed

EC signature date 13 April 2021

Start date 2 May 2022

End date 4 August 2024

Funded under

• SPREADING EXCELLENCE AND WIDENING PARTICIPATION

Total cost

€ 160 049,28

EU contribution

€ 160 049,28

Coordinated by

UNIVERSITA TA MALTA
Malta

Periodic Reporting for period 1 - OFF-GROUND (Topographically-driven fresh groundwater flow in offshore carbonate platforms.)

Reporting period: 2022-05-02 to 2024-05-01

Summary of the context and overall objectives of the project

This research was aimed to study Offshore bodies of Fresh Groundwater (OFF-GROUND/OFG), in carbonate aquifer, which represents a common geological setting along the coast of many Mediterranean countries.
OFG systems may represent an important global source of potable water in the future, considering that groundwater resources are rapidly declining in terms of quantity and quality as a result of over-exploitation, population growth, urbanisation, pollution and climate change. Industrial sectors involving seafloor engineering, petroleum exploration, carbon dioxide sequestration and ore deposit have also a direct interest in the evolution of OFG systems because their understanding could be key to a better understand fluid migration mechanisms.
The characteristics and dynamics of groundwater remain however poorly constrained, and the main effort of the research will be dedicated to build representative 3D geological and hydrogeological models of OFG associated to buried carbonate platforms reservoirs of the Malta Plateau, to specifically address the following questions: What is the 3D geometry, scale and rate of fluid circulation in carbonate platforms, at present and during sea level lowstands? What are the main controlling factors? What are the key processes driving fluid circulation in carbonate platforms, at present and during sea level lowstands? What is the role played by topographically-driven meteoric groundwater?

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

Activities mostly did follow the original plan.
- Technical and scientific effort has been mostly dedicated to: i) Well data analysis (more than 150 deep wells have been analyzed in detail); ii) 2D/3D static and dynamic Modelling.
- Field works (in southern Sicily and in the Apennines)
- Workshop / training: Short-Term Scientific Mission
- Knowledge transfer between the researcher and the host institution
- Teaching contribute at GSC2100 course at Malta University and at the course off: “3D subsurface interpretation and modelling” at Rome3 University
- Training: Modflow course, groundwater modelling class.
- Networking and collaboration: COST-ACTION n. CA21112 on OFFSHORE FRESHENED GROUNDWATER: AN UNCONVENTIONAL WATER RESOURCE IN COASTAL REGIONS? (OFF-SOURCE).
- Dissemination of project results: participation to several conferences; publication of the article “Extensive freshened groundwater resources emplaced during the Messinian sea-level drawdown in southern Sicily, Italy” published in November 2023 on Communications Earth & Environment. Following the publication of the article, a strong public interest from TV, Journals and online channel arise. As a result, several TV and online interviews followed, as well newspaper and online article and many mentions.

As main results and conclusion of the OFF_GROUND research project, it was possible to simultaneously identify in southern Sicily (Italy), the presence of fresh/freshened groundwater in the offshore (in the Ragusa carbonate aquifer), as well as discover an extensive, deep and freshened groundwater aquifer onshore (in the Gela Fm.). In particular:
- It was demonstrated the presence of deep fresh/freshened groundwater offshore southern Sicily in the Ragusa carbonate aquifer, by applying a petrophysical approach and inversion to well logs. Results demonstrate that the Ragusa carbonate formation have been invaded by fresh water also in the offshore, specifically in two deep Oil&Gas wells, 5 and 10 km from the coast, to depths down to 1000 m. Moreover, a "proof of concept" initial Dynamic Groundwater Model was built, allowing to investigate the effect of sea level changes on present-day distribution of fresh or freshened groundwater in the subsurface;
- it was possible to discover and document an extensive (17.3 km3) fresh/brackish groundwater body preserved in a deep (800-2100 m) carbonate platform aquifer (the Gela Formation) onshore southern Sicily, by integrating a comprehensive well data-set with 3D hydrogeological modelling. The distribution of this fossil groundwater is attributed to topographically-driven meteoric recharge driven by the Messinian sea-level drawdown, which we estimate to have reached 2400 m below present sea level in the eastern Mediterranean Basin, about 6 million years ago. Moreover, a regional 3D hydrogeological dynamic model was built, allowing to simulate groundwater’s movement in the geological time, both during the Messinian, as well as during glacial-interglacial sea level lowstands. Dynamic modelling appear to confirm and support reconstruction, and the main mechanism of topographically-driven meteoric infiltration during the Messinian sea-level drawdown.

As a result, study also effectively show that oil and gas industry techniques and data can be used to identify deep freshwater units, demonstrating these methods' applicability for Groundwater Exploration. In particular, it was demonstrated that:
- Repurposing geophysical/petrophysical methods originally designed for the oil and gas industry allows a streamlined approach in the exploration of deep aquifers.
- This approach maximizes the utility of existing resources and data for researchers by leveraging the extensive datasets and valuable information already collected during Oil&Gas exploration endeavors.

The research finally demonstrated the potential of offshore and deep freshwater in supporting sustainable development in region with limited water resources.

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)

The groundwater discoveries obtained through this research have significant implications as an unconventional future resource of water for Sicily as well as other Mediterranean coastal regions, which share similar geological setting and water scarcity issues.
The project has been listed as an ‘action’ at the UN Water Conference in March 2023, and later on kept updated with progresses.
The published article was particularly well received by a wide audience, including Media, TVs, news, in Sicily and Malta and at European scale.
In general, following good feedback received after publication of part of the results of the research, and presentations given at the conferences, positive feedback were received about the scientific quality of results, and the research gave a good contribution to the state of the art, as it regards offshore and deep freshened groundwater bodies hosted in carbonate aquifers.
From a scientific standpoint, the discover of the impact of the Messinian Sea-level Crisis over deep and possibly offshore preserved fresh-brackish groundwater in Sicily was not known, and it opens a new idea that could be investigated in the future in the whole Mediterranean area, opening a new “deep groundwater exploration phase”, with a high positive potential of new discoveries and socio-economic impact.

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