Assessment of
Connectivity of Mass Transport Deposits in the Subsurface Using Seismic-Scale
Outcrop Analogues
Garyfalou, Katerina1, Benjamin
Kneller1, Mason Dykstra2, David
Macdonald1 (1)
University of Aberdeen, Aberdeen, United Kingdom (2) University of California,
Santa Barbara, CA
We present a new approach to the
assessment of the effectiveness of mass transport deposits (MTDs) as baffles or
barriers to fluid flow in the subsurface. We use data from outcrop analogues at
a range of length scales (100 to 102 meters]), and representing different
textural types of MTDs; >100 m thick mud-rich debris-flow dominated deposit
from the Guandacól Formation (Carboniferous, La Rioja Province, NW Argentina;
>200m thick slide complex from the Fossil Bluff Group (Jurassic, Alexander
Island, Antarctica); 5 m thick sand-rich debris flow deposits from the Grès de
Peira Cava (Oligocene, SE France).
Using meso-(core)scale
outcrop descriptions of parameters that affect connectivity (net:gross, domain
size, fragmentation) we are able to calculate the connectivity in 3D by
transforming outcrop data from 2D to 3D. Correlation of each of these
parameters with connectivity allows us to identify a range of values over which
occurs the transition from effectively disconnected to effectively connected
volumes. This transition can be described by percolation theory. If this range
of values is treated as a rough threshold, and taking a threshold for each of
the three critical parameters, allows us to define a diffuse surface in three (or
more) parameter space that separates connected volumes from non-connected
volumes. This allows us to differentiate between MTDs that are complete or
leaky barriers, baffles, or even potential reservoirs, in the subsurface.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California