European Regional Conference and Exhibition

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The role of regional play based exploration in recent exploration success in the Dinarides

Abstract

A recent company re-entry into Albania and subsequent discovery of hydrocarbons in the Dinarides was underpinned by a regional prospectivity assessment of the Greater Adriatic region. The area of interest is located on the European Plate and has undergone a complex tectonic evolution which commenced with regional Mesozoic Tethyan extension and culminated in compression associated with the collision of Africa and Eurasia leading to the Tertiary Alpine orogeny. This region which extends from eastern Italy to the Balkans is a proven hydrocarbon province that contains some of the largest onshore oil fields in Europe, such as the Val D'Agri field in the southern Apennines and the Patos-Marinza field in Albania.

The present day structure of the region consists of two NW-SE-trending fold and thrust belts that are separated by a narrow underfilled foreland basin, which is partially overlain by the present day Adriatic Sea. The variation in current basin architecture was mapped using a broad grid of regional seismic and potential field data tied to the available well data and onshore geological mapping. This revealed new insights into the nature and timing of the sedimentary fill and structural evolution of the region. Dry hole analyses using well and seismic data isolated structural deformation caused by halokinesis from that caused by regional compressional stresses.

Regional charge is provided by a suite of prolific Mesozoic source rocks. A re-interpretation of the available geochemical database led to the division of the region into a suite of play domains. Thrust geometries, in some cases using weaknesses inherited from the Mesozoic rift architecture, and the position of the basal decollement exert a fundamental role on charge access. Reservoirs consist mainly of Triassic to Paleogene platformal to basinal carbonates and Oligocene to Pleistocene siliciclastics. Within the fold and thrust belt significant effective porosity is associated with the presence of pervasive fracture networks. The region shows a wide range of trapping geometries including both structural thrust and sub-thrust traps and stratigraphic trapping configurations in younger sequences. Regionally mappable first order unconformities control in large part the distribution of sealing sequences.

The study identified a suite of distinct play elements and petroleum systems which vary in their presence and importance across the region. This new interpretation of the petroleum potential of the region identified multiple distinct plays and enabled the company to customize the subsequent re-entry into the country.