Print this page3-D Modeling of Discrete Fracture Networks in a Complex Fold and Thrust Belt in the Northern Portion of the Eastern Cordillera Foothills, Colombia: Implications for Petroleum Exploration and Production
Javier Andres Acevedo1, Freddy Corredor2, David
Richards3, and John Jairo Aristizabal4
1 Universidad Nacional de Colombia, Bogotá D. C, Colombia
2 Harvard University, Cambridge, MA
3 Midland Valley Exploration Inc, Golden, CO
4 Ecopetrol S. A, Bogotá D. C, Colombia
A recent discovery in the northern culmination of the Eastern Cordillera
foothills, Colombia tested hydrocarbons from highly fractured
Cretaceous-Tertiary reservoirs on eastward-verging, imbricated thrust sheets,
above ramps which cut through the Cretaceous La Luna Formation. From a
relatively closely spaced grid of 2D seismic lines, surface geologic
information, and well image data, we constructed a 3D 
model
of this fold belt
that was sequentially restored and forward modeled using different directions of
shortening based on two models of regional basin development. Model 1 proposes a
single episode of NW-SE directed shortening, and Model 2 proposes two different
events of deformation with an initial episode of SW-NE oriented shortening,
followed by an episode of NW-SE oriented shortening. For each restoration we
model the 3D discrete fracture network, including joints parallel to fold axis
and conjugate sets of fractures, based on the dilatation of surfaces between the
unfold and fold stages, and maximum stress direction respectively, which is key
for new exploration and production efforts in this region. In order to test the
two kinematic hypotheses and implicitly the most appropriate simulated fracture
network, we compare observed fracture data from a satellite image, surface
geologic mapping and two borehole image logs with the modeled fractures. The two
episodes model
yielded three main fracture patterns in common with observed data
(N5W, N29E and N81E). These results suggest that the northern part of Eastern
Cordillera may have formed by two shortening episodes of different orientation
during the uplift of this thrust belt.
AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005