3-D Restoration
Using Elasticity and/or Elastic Relaxation
Moretti, Isabelle C.1, Marc O.
Titeux2 (1) IFP,
Tools for 3D restoration are now
available. A complex meshing of the model takes into account heterogeneities
due to the layering and facies variation. By coupling geometric modeling
software and a mechanical finite-element code, the geologist is now able to
impose the displacement on the main faults, in order to get an adequate restored
geometry. Unfolding with a mechanical approach also allows computing 3D strain
and stress fields within the main blocks. The geometry at various time steps,
as well as the major fault offsets, is defined by the user using a geomodeler,
whereas the restoration within the main “blocks” will be computed by a
finite-element mechanical code. For the unfolding, one needs to define the
deformation mode: elasticity, under the hypothesis of large deformation, seems
reasonable as a first approximation. It allows easy reverse modeling. Facing
the same problems, approaches based on a dynamic-relaxation solution are also
possible. Resolution using dynamic relaxation is based on the determination of
the stationary solution of the transient problem. It aims at accommodating the
displacement and velocity fields along the main faults by computing iteratively
the solution to the problem with new interface forces or degenerated cinematic
constraints.
We will show 3D restoration in complex
areas using both methodologies and compare the results in terms of computed
initial geometry, dilatation, stress and strain
tensors. The differences will be highlighted on the computed zones of high
internal deformation that we use to interpret as zone of higher fracturation.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California