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Falivene, Oriol1, Pau Arbués1, John A Howell2, Oscar Fernández1, Josep Anton Muñoz1, Mariano Marzo1
(1) University of Barcelona, Barcelona, Spain
(2) University of Bergen, Bergen, Norway

ABSTRACT: Facies Trends and Modelling Strategies within Slope Turbidite Systems: Insights from 3D Modelling of Outcrop and Subsurface Data from the Middle Eocene Ainsa System, South Pyrenean Foreland Basin, Spain

The Ainsa turbidite system is one of the worlds finest outcrop analogues for slope channel deposits. It is comprised of 3 cycles of channel development and abandonment. These cycles show a progressive southward, off-stepping relationship, controlled by the growth of structures within the basin.
An initial structural framework was built from outcrop and subsurface data. Mapped horizons and logged intervals were restored to paleohorizontal using an intraformational surface. Surfaces bounding the major channel complexes were reconstructed in the restored state based upon outcrop mapping, correlation and paleocurrent measurements. In addition to the major bounding surfaces a series of intra-channel-complex surfaces which represent the mean position for lateral and vertical facies changes were also reconstructed. Modelling grids were designed and built for each of the channel complexes. Population of the grid with facies was achieved through a partially deterministic and partially stochastic approach. Initial large scale features were placed deterministically, with smaller-scale heterogeneity being introduced from conditioned statistics derived from the outcrops.
Intra-formational breccias typically sit in the updip parts of the channel complex. These pass vertically-up and depositional-downdip into amalgamated sandstone bodies. The sandstones pass into heterolithic deposits which in turn pass to mudstones. The models illustrate the quantitative lateral and vertical trends that characterize structurally influenced slope-turbidite systems as well as forming the basis for understanding the fluid flow within similar sorts of reservoir systems. The models have also been used to compare modelling strategies and propose a best practice approach.

 

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.