Cross-Section Balancing – Surface Restoration – Volumic Restoration: All These Tools Exist, Now What To Do With Them?

Isabelle Moretti
IFP, Rueil-Malmaison, France

The principles of the structural geology have been used for long time to propose the horizon and fault geometry. They are based on top-bottom relationship of the horizons and on the fault-horizon cut-off theoretical angles deduced from surface observations and laboratory experiments. Now the subsurface data acquisition is in a mature phase and commonly the need to invent the markers that do not appear on the seismic has disappeared. However structural geology and restoration process remain useful to improve the coherence of the subsurface data interpretation and to have an idea of the initial geometry and of the deformation versus time. Restoration could be done in cross-section, 2D, in surface, 2.5D and in volume, fully 3D. The 3D tools that we used, is based on a mechanical retro-deformation. If the preservation of area or volume is the main hypothesis, variations happen locally and are commonly interpreted in term of fracture probability. One way to preserve volume (resp. area) is to preserve area (resp. length) and thickness; other solutions exist that correspond to different deformation modes.

The main goal of this presentation will be to synthesize these methods and to discuss, on real cases, what the geologists may expect from a 2D, and 2.5D and a 3D restoration in term of improvement of the geometries, knowledge of the kinetic of the deformation and quantification of the strain tensor. Retro-deformation could be also seen as a first step for a direct mechanical modeling or for the petroleum system modeling. Up to which point?

 

AAPG Search and Discover Article #90066©2007 AAPG Hedberg Conference, The Hague, The Netherlands