Exploration in the Rhone-Maritime License (French Mediterranean): Part I - Seismic Interpretation and Salt Reconstruction

Janine Zweigel¹, Roman S. Ianev², Are Tømmerås¹, Maik Inthorn¹, and Nathalie Bordas-Le Floch^2
1SINTEF Petroleum Research, Trondheim, Norway
²Melrose Resources plc, Edinburgh, United Kingdom

The interpretation of newly acquired regional 2-D seismic has led to renewed exploration interest in Mio-Pliocene deep-water reservoir plays in the confined Gulf of Lyon Basin in the Western Mediterranean. The basin originated in the Oligocene as a syn-sedimentary extensional back-arc system. Subsequent Miocene-Recent post-rift subsidence was allied to increasing sediment supply due to increased run off from the developing Alpine and Pyreneen mountain belts. As a result the basin became increasingly dominated by turbiditic deposition as a part of an upward-shoaling succession during the Miocene.
The basin fill subsequently records a dramatic shallowing episode during the late Miocene (Messinian) in response to desiccation of the Mediterranean Sea with the development of deeply-incised canyons in proximal areas and thick evaporite deposits in the offshore. Post-rift sedimentation resumed on the margin following Pliocene transgression. Burial and tilting triggered decollement on the mobile Messinian evaporites and down-slope movement of the Plio-Quaternary sediments resulting in the formation of a spectacular linked extensional-translation-compressional system of normal faults and folds with concomitant effects on sedimentation.
Reconstruction of palaeo-water depth and geometries using modified back-stripping methods suggest that the main salt movement occurred after 4Ma. Two salt window areas, providing potential hydrocarbon migration pathways, are mapped in the area; the first one is connected to slope processes to the north, and the second one is in the deep diapir zone. Between these two zones the salt works as an efficient migration barrier and potentially trapping hydrocarbon accumulations in a number of structural and stratigraphic traps in the early Messinian. Furthermore, basin subsidence and modelling of the source rock maturation history have provided a testable model of the newly identified play opportunities.

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece