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Accueil > Documents > Pages personnelles > GAY Aurélien

GAY Aurélien

Lecturer in basin geology : fluid migration structures, deformation and faulting related to fluids in sedimentary basins

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GAY Aurélien

Lecturer in Basin Geology

University of Montpellier

Laboratoire Geosciences

34095 MONTPELLIER Cedex 5

FRANCE

Contact :

Tel : +33 (0) 4 67 14 45 98

mail : aurelien.gay@gm.univ-montp2.fr

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RESUME :

Born : 1976

AAPG Member

ASF Member

http://www.researcherid.com/rid/D-2192-2013

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PARCOURS PROFESSIONNEL

2012-2013 : Head of Master “Géologie de l’exploration et des reservoirs”

2010-2011 : Co-head of Master « Réservoirs Géologiques » Univ. Montpellier 2, France

Since 2008 : Lecturer, Laboratoire GM, Université Montpellier 2, France

2006-2008 : Senior Geologist (NERC), National Oceanography Centre of Southampton (NOC), UK

2004-2006 : Junior Geologist, National Oceanography Centre of Southampton (NOC), UK

2003-2004 : Assistant professor, Université Montpellier 2

2002-2003 : Post-Doctorate, Université de Montpellier 2

PARCOURS UNIVERSITAIRE

2010-2011 : HDR (Agreement for PhD supervision), Univ. Montpellier 2 : "the role of fluids in sedimentary basins

1999-2002 : PhD Thesis, Sciences de la Terre, Sédimentologie - Lille 1

PROJETS SCIENTIFIQUES

> Leader of 6 national projects between 2003 and 2012

> Partner of 1 "ANR Blanche" in 2009

> Leader of 1 internal project, laboratoire Géosciences Montpellier en 2009

> Leader of 1 NERC Full Grant, University of Southampton, UK , in 2007

> Leader of 1 NERC Young Research Grant, University of Southampton, UK, en 2006

> Partner of 1 project of the "région Pays de la Loire" « fluid migration modeling" in 2007

CONFERENCES & COMMUNICATIONS

20 conferences as invited speaker since 2001

2 conferences as chairman at EGU in 2008 and 2011

RESEARCH ADMINISTRATION

> Co-Editor of a special issue in Marine Geology (2012)

> Reviewer of 22 scientific articles

> Member of the Peer Review College (2007-2008), NERC, UK

> PhD thesis reviewer, Lieven Naudts (2010). RCMG, Université de Gent, Belgium

> Reviewer for research projects of the belgium national agency in 2005

> Reviewer for research projects of the NSF (USA) in 2006

> Leader of the seismic imagery room at the university of Montpellier

SCIENTIFIC PRICES

> INI-Post-Doc price of the french ministry of research (2007)

RESEARCH SUPERVISION

> 1 thesis (ongoing)

> 2 thesis (2008 and 2013)

> 7 master internships

PUBLICATIONS

> 21 Articles, 10 as first author (see list below)

> 25 communications with committee

> 6 reports

CRUISES

3 cruises in West Africa (1999-2002)

1 IODP cruise in Gulf of Mexico (Exp 308, 2005)

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Research Highlights :

For over 50 years, sedimentary basins have been considered as the lithosphere’s surface film, belonging to the subsurface domain and containing the vast majority of accessible mineral and energy resources. Beyond their human use, sedimentary basins are more importantly the ultimate exchange interface between the earth’s main reservoirs (Figure 1).

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Firstly, between the upper lithosphere and the atmosphere-hydrosphere pair, exchanges are mainly vertical. Next, between the onshore reservoirs, i.e. on the continental part, and the offshore reservoirs, i.e. in the submerged part of the margins, exchanges are lateral and may take place over great distances.
Recent studies of fluid migrations in sedimentary basins have shown that these phenomena are ubiquitous (Berndt, 2003) and interact with the surrounding sedimentary rocks over the basin’s history, from its early opening stages, to the mature filling, or even the ultimate exhumation stages. Finally, these fluids act as major markers of the geodynamic events that structure the basins and their mobilisation is directly governed by allocyclic parameters such as climate and sea-level variations.
The end goal is thus to generate a concept of "fluid sequences" that, in a similar fashion to sequence stratigraphy, will be used as a direct approach to determine the migration paths, potential traps and to quantify the volume and nature of expelled fluids, and as a reverse approach to determine the evolutionary status of a sedimentary basis and to infer its geodynamic context at any given period of its history. We are beginning to gain a good understanding of tectonic-sedimentary couplings, sedimentation-fluid couplings through diagenesis and fluid-tectonic couplings through fault behaviour. The aim is thus to extend these concepts to a more highly integrated form of tectonic-sedimentation-fluids coupling, an approach that has never to date been implemented, or in a piecemeal fashion.

Currently, gaining an understanding of fluid transfers through sedimentary basins represents both a societal and fundamental issue (Figure 2) (Berndt, 2005). Due to their nature (CO2, CH4, H2S mainly) their expulsion onto the seabed could impact oceanic or even atmospheric chemistry. These fluids are thus directly involved in geochemical balances between the earth’s main reservoirs, from the lithosphere to the atmosphere, via the biosphere. Recent studies have thus shown that their massive expulsion could be responsible for global climate change, such as during the Paleocene/Eocene thermal maximum (Dickens et al., 1998 ; Dickens et al., 1997). Their expulsion also represents a risk to slope stability (Cochonat et al., 2002 ; Evans et al., 1996 ; Prior and Coleman, 1984 ; Yun et al., 1999) with ensuing consequences for human settlements (Elverhøi et al., 2002 ; Sultan et al., 2001). They also supply numerous ocean bed chemosynthetic communities (Boetius, 2000 ; Sibuet, 2003) that have revolutionized our understanding of the appearance of life on earth. Moreover, the volume of fluids trapped in sedimentary basins is of value in terms of resource, a major issue for the years to come.

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Many studies have attempted to establish a relationship between fluid seeps and their supposed source (Gay et al. 2007 and references). The architecture of the migration network, however, has long remained uncertain and neither the source of the fluids, nor the initiation processes (excess pressure for example), nor their mode of expulsion (episodic, catastrophic, cyclical), were clearly established.
The use, in academic world from the 2000s, of 3D seismic data and high-resolution seabed imaging, has led to significant breakthroughs by first defining a geophysical signature : fluid pipes (or chimneys), whose diameter may be of up to 150-200 m, can be identified on seismic profiles thanks to the gas they contain, or to carbonates that precipitate by biochemical interaction with host sediments (Figure 3). These pipes, when they reach the seabed, are generally "capped" by a fluid seep structure (pockmark or mud volcano), whose diameter may reach 800 m for a depth of 80 m (Baraza et al., 1999).

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It was then necessary to define a mineralogical and geochemical signature using in situ samples collected from fluid seeps or from bore holes. The analyses showed that the main elements conveyed by the fluids are methane and hydrocarbons (ethane and heavier compounds), carbon dioxide, sulphates (that precipitate to barite and celestite), sulphides (that precipitate to pyrite), bicarbonate ions (that precipitate to carbonates), along with a host of other elements determined by the source of the fluids, or by their interactions with sedimentary bodies or structural objects encountered during their migration. A first order fluid migration network (Figure 4) has been defined (Gay et al, 2007).

List of Publications

A22- Tribovillard, N., Armynot du Châtelet, E., Gay, A., Barbecot, F., Sansjofre, P. and Potdevin, J-L. (2013). Geochemistry of cold seepage-impacted sediments : per-ascensum or per-descensum trace metal enrichment ?.Chemical Geology, V. 340, p. 1-12.

A21- Monnier, D., Gay, A., Imbert, P., Soliva, R. and Lopez, M., 2013. Flow direction and genetic model of a fossil sand injection network in the Vocontian Basin, SE France. Journal of Structural Geology.

A20- Monnier, D., Gay, A., Imbert, P., Soliva, R. and Lopez, M., 2013. Fossil sand injections as marker of the paleo-stress field, the structural framework and the distance to the sand source : example in the Vocontian Basin, SE France. Journal of Structural Geology.

A19- Monnier, D., Imbert, P., Gay, A., Lopez, M. and Mourgues, R., 2013. Pliocene sand injectites from a submarine lobe fringe during hydrocarbon migration (and sal diapirism) : a seismic example from the Lower Congo Basin. Geofluids.

A18- Monnier, D., Gay, A., Imbert, P. and Lopez, M., 2013. Sand injections vs. sedimentary processes : geophysical evidences along the margins of a turbidite channel system, a case study from the Lower Congo Basin. Marine Geology.

A17- Anka, Z., Berndt, C. and Gay, A., 2012. Hydrocarbon leakage through focused fluid flow systems in continental margins Preface. Marine Geology, 332 : 1-3.

A16- Laurent, D., Gay, A., Baudon, C., Berndt, C., Soliva, R., Planke, S., Mourgues, R., Lacaze, S., Pauget, F., Mangue, M. and Lopez, M. (2012). High-resolution architecture of a polygonal fault interval inferred from Geomodel applied to 3D seismic data from the Gjallar Ridge, Vøring Basin, Offshore Norway. Marine Geology.

A15- Gay, A., Mourgues, R., Berndt, C., Bureau, D., Planke, S., Laurent, D., Gautier, S., Lauer, C. and Loggia, D. (2012). Anatomy of a fluid pipe in the Norway Basin : initiation, propagation and 3D shape. Marine Geology.

A14- Berndt, C., Jacobs, C., Gay, A., Elliott, G., Evans, A., Long, D., and Hitchen, K. (2012). Polygonal seabed deformation in the Hatton Basin, North Atlantic. Marine Geology.

A13- Mourgues, R., Bureau, D., Bodet, L., Gay, A. and Gressier, J., 2011. Formation of conical fractures in sedimentary basins : Experiments involving pore fluids and implications for sandstone intrusion mechanisms. Earth and Planetary Science Letters, 313 : 67-78.

A12- Mourgues, R., Gressier, J.B., Bodet, L., Bureau, D. and Gay, A., 2011. “Basin scale” versus “localized” pore pressure/stress coupling e Implications for trap integrity evaluation. Marine and Petroleum Geology, 28(5) : 1111-1121.

A11- Gay, A., Takano, Y., Gilhooly III, W.P., Berndt, C., K. Heeschen, Suzuki, N., Saegusa, S., Nakagawa, F., Tsunogai, U., Jiang, S.Y., & Lopez, M. (2010). Geophysical and geochemical evidence of large scale fluid flow within shallow sediments in the eastern Gulf of Mexico, offshore Louisiana. Geofluids. doi : 10.1111/j.1468-8123.2010.304.x

A10- Moore, C., Iturino, G.J., Flemmings, P., Hull I. and Gay A. (2007). Fluid migration and state of stress above the Blue Unit, Ursa Basin : Relationship to the geometry of injectites. OTC, Paper 18812.

A9- Gay, A., Lopez, M., Berndt, C. and Séranne, M., (2007). Geological controls on focused fluid flow associated with seafloor seeps in the Lower Congo Basin. Marine Geology, 244 : 68-92.

A8- Gay, A. & Berndt, C. (2007). Cessation/reactivation of polygonal faulting and effects on fluid flow in the Vøring Basin, Norwegian Margin. Journal of the Geological Society of London. 164, 129-141.

A7- Gay, A. (2006-e). Reply to comments on “Seafloor facies related to upward methane flux within a Giant Pockmark of the Lower Congo Basin”. Marine Geology. 232, 103-104.

A6- Gay, A., M. Lopez, H. Ondreas, J.-L. Charlou, G. Sermondadaz & P. Cochonat (2006-c). Seafloor facies related to upward methane flux within a Giant Pockmark of the Lower Congo Basin. Marine Geology. 226, 81-95.

A5- Gay, A., M. Lopez, P. Cochonat, M. Seranne, D. Levache & G. Sermondadaz (2006-b). Isolated seafloor pockmarks linked to BSRs, fluid chimneys, polygonal faults and stacked Oligocene-Miocene turbiditic palaeochannels in the Lower Congo Basin. Marine Geology. 226, 25-40.

A4- Gay, A., M. Lopez, P. Cochonat & G. Sermondadaz (2006-a) Evidences of early to late fluid migration from an upper Miocene turbiditic channel revealed by 3D seismic coupled to geochemical sampling within seafloor pockmarks, Lower Congo Basin. Marine and Petroleum Geology. 23, 387-399.

A3- Ondreas, H., J-L. Charlou, K. Olu, Y. Fouquet, P. Cochonat, A. Gay, B. Dennielou, J. P. Donval, A. Fifis, T. Nadalig, & M. Sibuet. (2005-a) Integrated "in situ" study of a deep giant pockmark on the Congo-Angola margin. Geo-Marine Letters. 25, 281-292.

A2- Gay, A., M. Lopez, P. Cochonat, & G. Sermondadaz (2004) Polygonal faults-furrows system related to early stages of compaction-Upper Miocene to present sediments of the Lower Congo Basin. Basin Research, 16, 101-116.

A1- Gay, A., M. Lopez, P. Cochonat, N. Sultan, E. Cauquil & F. Brigaud (2003) Sinuous pockmark belt as indicator of a shallow buried turbiditic channel on the lower slope of the Congo Basin, West African Margin, in P. Van Rensbergen, R. R. Hillis, A. J. Maltman, & C. K. Morley, eds., Subsurface Sediment Mobilization, Geological Society of London, Special Publications, 216, 173-189.