Alan D Gibbs¹

(1) Midland Valley Exploration Ltd, Glasgow, Scotland

ABSTRACT: Inversion - Interpreting the Deformation Path - Why does it matter?

Most models for inversion focus on understanding the 2D structural development of extension then compression, or occasionally compression then extension. Coupled with this are broad-based models to account for the stacking of depositional and erosional packages driven directly by the structural inversion. Inversion, whether driven by the extension - compression cycle, transtension or halokinetic movement is dominantly a 3D process. When modeled in 3D it becomes apparent that the 2D cross-sectional view underplays the importance of these coupled systems. As many of our basins of key commercial interest contain or are dominated by long-lived inversion components an understanding of the effect of these evolving geometries is of vital concern.

This paper illustrates the key influences on stratigraphy, hydrocarbon systems, coupled with structural control of the deformation path in 3D. Common situations are illustrated with reference to salt and frontal tectonic inversions situations. A methodology for the analysis of the coupled inversion process is described through the use of 3D modeling. Breaching of structural, sediment and fluid fairways is an integral part of the inversion process and the coupling of these elements provides the basis for a predictive approach to exploration in inverted basins. The overall inversion framework then provides a basis for detailed prospect and field scale analysis in inverted regimes.

The more traditional use of use of 2D cross-sections and maps to identify the key processes is contrasted with 3D analysis. Potential errors arising from a necessarily incomplete 2D approach can lead to invalid decisions in both exploration and production.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado