--> Abstract: Delta-Front to Slope Channels in the Eocene Sobrarbe Deltaic Complex, Ainsa Basin, Spain: Analogue for Sediment Transport from the Chayvo to Arkutun Dagi Fields, Russia, by Jeffrey K. Geslin, Timothy Demko, and Ted Apotria; #90082 (2008)

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Delta-Front to Slope Channels in the Eocene Sobrarbe Deltaic Complex, Ainsa Basin, Spain: Analogue for Sediment Transport from the Chayvo to Arkutun Dagi Fields, Russia

Jeffrey K. Geslin1, Timothy Demko2, and Ted Apotria3
1ExxonMobil Development Company, Houston, TX
2ExxonMobil Exploration Co., Houston, TX
3ExxonMobil Oil Indonesia, Jakarta, Indonesia

The Eocene Sobrarbe deltaic complex, Ainsa Basin, northern Spain is composed of seismic-scale (~150-250m) clinoforms deposited in a small, tectonically active basin in the Pyrenean FTB. The Sobrarbe deltas comprise a composite sequence set partially equivalent to, and younger than, the well-studied slope channel complexes near the town of Ainsa.

Numerous small, sinuous channels encased in shales are documented in delta-front deposits of the Sobrarbe complex. These channels are generally non-amalgamated, contain abundant shale rip-up clasts, have low aspect ratios, and mark the tops of parasequences in HSTs. The channels are interpreted to transition basinward into slope channels that provided a conduit for transport of paralic sands to a deep-water slope setting. It is possible that the delta-front channels coalesce down depositional dip into larger slope channel complexes in the upper part of the stratigraphic section near Ainsa. Alternatively, the slope channel complexes near Ainsa could represent only LST deposits and the equivalent of the HST Sobrarbe channels have not been recognized in that area. The genetic and stratigraphic relationship between the Sobrarbe delta-front channels and the larger slope channels observed at Ainsa is the focus of ongoing research.

The Chayvo oil/gas field contains Upper Miocene mixed wave- and fluvial-influenced deltaic strata deposited in a transpressional setting. The clinoforms at Chayvo (~150-200m) contain delta-front slope channels that coalesce downdip and transition basinward into toe-of-slope fans at the Arkutun Dagi field. The seismically-imaged channels at Chayvo are geometrically similar to those in the Sobrarbe complex. Channels in the Sobrarbe and at Chayvo are examples of the connection between shallow and deep-water reservoirs, and further study could help in understanding their genetic relationship.

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery