Workflows for
Geomechanical Restoration and Forward Modelling in Fold and Thrust Belts:Comparison with Geometric Methodologies, Applications and
Limitations
Griffiths, Paul1, Laurent
Maerten2 (1) BG Group,
Fold and thrust belts represent an
important environment for world hydrocarbon exploration and production.
However, in these settings seismic imaging of subsurface features is often poor
due to structural complexity, with limited structural orientation data at depth
to constrain interpretations. The geoscientist is required to develop a
subsurface model that honours the available data but is often geologically
model-driven. Section construction and geometric restoration have a long
history of application in thrust belts, providing a consistent set of geometric
constraints which help to test the interpretation and geological model.
However, geometric techniques are often time-consuming and do not attempt to
incorporate any physical deformation of the rocks.
We present an alternative methodology for
restoration in fold and thrust belts using geomechanical elastic finite element
code that allows simultaneous restoration of all fault blocks to a convergent
solution that is repeatable. Using the geomechanical approach, potential
interpretation inconsistencies appear as anomalous stress or strain
concentrations and gaps and overlaps between the hangingwall and footwall.
Modifications to the present-day interpretation can be rapidly and consistently
restored to a unique geometry.
We compare the process and results of
restorations and forward models using geometric techniques (flexural slip and
fault parallel slip) and the geomechanical approach using synthetic and natural
examples. The comparison is used to examine the uses and limitations of both
geometric and geomechanical restoration approaches.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California