Gironde Estuary & Atlantic Coast Fieldtrip

This training presents the reservoirs that deposited in modern environments, ranging from fluvial to estuarine (tide- and wave-dominated) and coastal marine, at exploration and production scales.

You will visit world-class shallow water environments of deposition and acquire an in-depth knowledge of the reservoir geo-bodies formed in these environments:

- In the Gironde estuary, a worldwide reference model for tide-dominated incised valleys, reservoirs will be examined at exploration scale along a 200 km long facies transect, from fluvial point bars to heterolithic estuarine point bars and tidal bars, and to the tidal inlet channel-fill located at the estuary mouth. The exceptional core and very high resolution seismic database allow describing the reservoir geo-bodies at production scale (geometries, heterogeneities).

- In the Arcachon estuary, a wave-dominated incised valley, tidal channel reservoirs and tidal flats will be examined along a 40 km long facies transect, from the inner estuary where small-scale meandering tidal channels incise a mud flat, to the outer estuary where larger tidal channels incise a sand flat and amalgamate seaward to generate a large-scale tidal inlet channel-fill at the estuary mouth. Here again, the exceptional core and very high resolution seismic database allow describing the reservoir geo-bodies at production scale (geometries, heterogeneities).

- In the Atlantic wave-dominated oceanic coastline, adjacent to these embayments, beach, shore face and aeolian coastal dune deposits will be presented thanks to spectacular trenches in the backshore and foreshore, cores and GPR lines.

By the end of this course, participants will be able to:

1. Characterize the facies of the reservoirs formed in shallow water environments of deposition:   fluvial, estuarine (tide- and wave-dominated), coastal marine (beach and shoreface) and aeolian.
2. Assemble detailed facies core description, in order to identify the reservoirs formed along an updip-downdip facies transect (from fluvial to shoreface).
3. Assess the range of reservoir geometry formed in each environment and understand the specific processes controlling the range of reservoir geometry within wave- and tide-dominated incised valleys.
4. Evaluate the heterogeneities of the reservoir geobodies formed in each environment and assess the specific processes controlling the range of reservoir heterogeneity along an updip-downdip facies transect (from fluvial to shoreface).
5. Reconstruct incised valley large-scale reservoir architecture within a sequence stratigraphic framework, with the help of cores and seismic lines.

Learning-by-doing, based on extensive exercises during the field trip. The teaching material is composed of field guide books, power point presentations, poster sessions (before and after each field stop), core descriptions (high-quality cores, preserved in epoxy), very high resolution seismic lines, and production geology exercises.

Each participant is required to provide a yearly medical certificate before attending this field course. Participants must be in good health and physical conditions to attend.
Attendees must also wear adapted shoes (suitable for sandy and wet shore) and bring clothing for hot day time temperatures (sun hat, sun glasses, etc.).

• Introductory lecture presenting the environments of deposition of the Aquitaine basin.
• Fluvial meandering channels with sandy-conglomeratic point bars.
• Criteria to recognize the Fluvial-Estuarine facies transition.
• Estuarine meandering channels, with heterolithic point bars.

• Estuary funnel sandy tidal bars (estuarine bay-head delta), ichnofacies.
• Internal architecture of the estuarine bay-head delta: reservoirs and internal seals.
• Production geology exercise: tidal bars well correlations, with integration of production data.

• Coastal marine oceanic beaches: backshore, foreshore and swash bars deposits.
• Shoreface deposits: storm graded beds, ichnofacies.
• Sequence stratigraphy of the interfluves of the Gironde incised valley (adjacent to estuary mouth).
• Sequence stratigraphic model and reservoir architecture of the tide-dominated Gironde incised valley.

• Inner estuary meandering tidal channels and muddy tidal flats, ichnofacies.
• Outer estuary tidal inlet channel-fill and sandy tidal flat.
• Sequence stratigraphic model and reservoir architecture of the wave-dominated Arcachon incised valley. Comparison with the tide-dominated Gironde incised valley.
• Aeolian coastal dune field, with internal architecture of Europe’s tallest dune (Pyla dune).