The Role of Active Structural Growth in Controlling Deep-Water Reservoir Systems and Petroleum Prospectivity in the Confined Gulf of Lyons Basin, Western Mediterranean

Ianev, Roman S.¹, Nathalie Bordas-Le Floch¹, John R. Underhill², Richard J.W. Bunt¹ (1) Melrose Resources plc, Edinburgh, United Kingdom (2) School of Geosciences, The University of Edinburgh, Edinburgh, United Kingdom

The interpretation of a newly acquired regional 2-D seismic survey and its integration with onshore field exposures in neighbouring parts of Southern Europe has led to renewed exploration interest in Neogene (Mio-Pliocene) deep-water reservoir plays in the confined Gulf of Lyons Basin in the Western Mediterranean. It can now be shown that the basin originated in the Oligocene as a syn-sedimentary extensional back-arc system that included the analogous Sarcidano Basin of Sardinia. Subsequent Miocene-Recent post-rift subsidence was allied to increasing sediment supply due to increased run off from the developing Alpine and Pyreneean mountain belts. As a result the basin became increasingly dominated by turbiditic deposition as 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 dessication 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 evaporates and down-slope movement of the Plio-Quaternary sediments with the formation of a spectacular linked extensional-translation-compressional system of normal faults and folds with concomitant effects on sedimentation. Interpretation of seismic facies demonstrates how active structural growth of the mobile evaporite system controlled sediment dispersal patterns and petroleum prospectivity in the sub-salt and supra-salt turbidites. Furthermore, basin subsidence and modelling of the source rock maturation histories has provided a testable model of the newly identified play opportunities.