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.