AAPG Geoscience Technology Workshop

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West Katakolo field. A Proven Hydrocarbon Play for Future Exploration in Western Greece

Abstract

The offshore West Katakolo field is an oil and gas fractured carbonate reservoir, currently the only hydrocarbon discovery in Western Greece. The field was discovered back in the early 80's; nevertheless development never commenced due to the following reasons; limited reserves estimation and low oil prices. However, in 2014 a re-evaluation of the field due to the re-processing of the legacy 3D seismic dataset resulted in a significant increase of 2P oil reserves to 10,7MMbbls and 2C gas resources to 6.2 BCF. Therefore the development of West Katakolo field was recognized as an economically viable project. Eventually the field is planned to be developed by four ERD wells aiming to achieve a daily production of 3000 bbls. The West Katakolo structure was delineated using the legacy 2D and 3D seismic data which were recently reprocessed resulting in an enhanced resolution 3D seismic volume. The West Katakolo reservoir is an Eocene to Cretaceous basinal carbonate interval, heavily fractured and locally karstified following of a prolonged subaerial exposure of the structure from the Oligocene to the lower Pliocene. The structure is charged by the Triassic evaporitic section which is a proven source rock in the region. The structure is sealed by on lapping Pliocene clastics predominantly shales. The West Katakolo field belongs to the Ionian geotectonic zone which spans Albania to Western Greece. It is predominantly a fold and thrust belt resulting from the subduction of the Apulian platform. The field is located in a geological setting equivalent to the Albanian producing fields towards the north, showing similarities in terms of both being fractured basinal carbonates reservoirs sourced by the Triassic source rocks. Three wells penetrated the West Katakolo structure discovering 130 m oil rim and a 115 m gas-cap mainly hosted within a densely fracture network. The reservoir was tested flowing approximately 1100-1400bbls/d of 28o API sour oil and 14-23 MMSCF/d gas. Moreover, gas shows were observed in the deeper carbonate section below the OWC in two of the wells, indicating a deeper interval with upside potential. The fact that recently ten onshore and offshore blocks in Western Greece have been or are in the process of being awarded to operating oil and gas companies shows the increasing interest in the region. The West-Katakolo field is an excellent analogue of a Triassic hydrocarbon play that comprises deep-marine thrusted Eocene to Cretaceous carbonate reservoirs sealed by Pliocene clastics. It is believed that similar prospects exist in the entire Western Greece region.