Inversion Structures: Geometry and Petroleum Potential

Abstract

Inversion tectonics (or more generally reactivation of older structural elements) is a widespread structural phenomenon. From a petroleum exploration veiwpoint, it plays an important but very ambiguous part, since it may either create the favorable conditions for structural trapping or, on the contrary, destroy previous hydrocarbon accumulations. Therefore, it is important to analyze the mechanisms and geometry of such deformations. An extensive analog modeling program was designed for this purpose and implemented by sandbox experiments. Deformation was analyzed in real time by x-ray tomography. A special emphasis was put on studying the effects of strike-slip components of the displacement along the reactivated feature. Analog models with know experimental conditions were then compared with field and seismic examples. Once inversion geometries have been recognized, it becomes important to reconstruct the burial history of the postulated source-rock horizons, which are often located in the invented trough. In this case, the timing of maturation vs. structuration becomes a critical factor. This can be implemented through three-dimensional decompaction softwares. This paper is based on joint research projects by TOTAL, ELF, IEF, and AGIP.