Third EAGE Eastern Mediterranean Workshop

Presalt seismic imaging and prospectivity in the eastern Mediterranean is challenged by the overlying complex Messinian salt. Using seismic examples, we present the different styles of salt (complexity and composition) that can be observed in the eastern Mediterranean as well as providing examples of the different presalt plays that may be targeted by explorationists in the region.

After the preparation of shale sample including polish and water equilibrium experiments, we take advantage of SEM technique to acquire original and dehydrated captures of chip shale processed under different moistures, count pore data and remarkable lengths with Image Pro plus visually and analyze statistical parameters on the basis of SEM pictures, then calculate changing ratio between original and processed parameter values under different moistures, in order to get a visual trend, curves of changing ratio with moisture are drawn, we discover complicated moisture influence pattern of organic pores and inorganic pores, two types of pores get influenced, this pattern can explain the increase of wellhole instability and earthquake risk.

The interpretation of offshore 2D seismic lines has here been integrated with onshore drone-based digital photogrammetry and fieldwork to shed new lights on the stratigraphic and reservoir properties of Eastern Mediterranean Miocene carbonate units.

A near-top Miocene carbonate platform seismic reflector has been mapped regionally in and around the Eratosthenes seamount. These shallow-water carbonate units are buried under Messinian evaporites in structurally lower positions; however, such seal layer is missing on the central Eratosthenes high. Pliocene-Quaternary pelagic carbonate layers record a recent history of fast subsidence and platform drowning.

Miocene shallow-water carbonates have so far proven poor reservoir units offshore, unlike the world-class Cretaceous reefal reservoir rocks of the Zohr and Calypso discoveries. The preliminary reservoir properties of an isolated Miocene reef outcropping in Cyprus have here been described. Hand-samples generally show low permeability and low-medium porosity; however dense open fracture networks have been mapped. Within the carbonate build-up, several depositional facies were discriminated, each with different reservoir and fracture parameters.

These observations suggest that Miocene reefs could serve as a commercial reservoir, although well placement should be optimized by targeting the best intra-platform facies belts through the integration of 3D seismic geomorphology and more detailed reservoir outcrop analogue studies.

This project attempts to extract information regarding the stratigraphy and source rock potential of the deeply buried deposits in the Mediterranean Ridge (South of Crete marine region). Due to the lack of deep wells in the region, the only avaliable material comes from mud volcanic (mud breccia) samples recovered from various scientific expeditions. Sedimentary cores from Gelendzhik, Moscow, Nice, Toronto and Dublin mud volcanoes were used. The actual samples of this study consists of consolidated clasts that were included in the mud breccia deposits of each core. The stratigraphic origin of the clasts were determined by studying its calcareous nannoplankton content and subsequently, rock eval pyrolysis and vitrinite reflectance measurements were performed. Combining the study’s results with seismic reflection profile images, leads to a higher-level understanding of the region’s stratigraphy and source rock distribution.

Shear wave velocity (Vs) is regarded as one of the most crucial parameters in reservoir geotechnics because of its employment in the determination of other petrophysical parameters. Two main sources of data, including laboratory data extracted from core examination and petrophysical logs, are used for Vs estimation. Petrophysical logs are the most common data to determine Vs, because of their availability and simplicity in recording and analyzing. Thus far, many empirical equations have been proposed to determine Vs applying petrophysical logs. However, these empirical methods remarkably suffer from the low degree of precision delivered when applied to a different field. Artificial intelligence models have been found to be efficient tools in addressing this lack of generalizability problem. Therefore, in this study, by combining least square support vector machine with genetic algorithm, a hybrid artificial intelligence model was developed to accurately predict Vs using six petrophysical logs as input variables. The accuracy of the hybrid model was then compared with five common empirical models previously proposed. The results achieved present that the newly configured model evaluated can make a much more precise estimation of Vs (R2= 0.9813, RMSE=0.411 km/s) when compared to all five empirical models reviewed in the present research.

The Mediterranean is characterized by a wide range of carbonate petroleum systems. In this work, we present a synthesis of these carbonate petroleum systems, based on data contained within CarbMed GIS, a tool for geological and E&P data synthesis and knowledge management that supports the full range of hydrocarbon exploitation activities. The GIS project consists of geological data (e.g. logs, wells, sections, maps, fields) associated with a comprehensive geo-database, which provides information on stratigraphy, sedimentology, diagenesis, fluid parameters and petroleum system elements.

In the Greater Mediterranean area, 26 proven petroleum systems that include hydrocarbons reservoired in shallow marine and basinal carbonate reservoirs have been identified and mapped. Within each one of these, a number of carbonate plays have been identified and described based on reservoir characteristics.

Results show an asymmetrical framework of petroleum systems and play across the Mediterranean provinces, with the northern area dominated by plays associated with the large and long-lived isolated carbonate platforms of Adria and sourced primarily by deep water and intraplatform basin carbonate source rocks and the southern and eastern areas characterized by plays associated with smaller sized carbonate systems that were deposited on mixed carbonate-clastic shelves.

An extensive potential source rock sampling survey was conducted in Ionian Zone, Epirus region, western Greece. Several samples were collected from the known potential source rock intervals (Triassic formations, ‘Lower Posidonia Shales’, ‘Upper Posidonia Shales’, ‘Vigla Shales’) as well as from new intervals showing promisin g source rock characteristics (dark color, clay content etc.). The samples were examined by organic geochemical means using the Rock-Eval 6 instrument by Vinci Technologies, France. Concerning the known potential source rock intervals, the ‘Lower Posidonia Shales’ show generally good petroleum potential, ‘Upper Posidonia Shales’ show no hydrocarbon potential, ‘Vigla Shales’ show fair to good petroleum potential but only in one locality. Several Triassic black carbonate samples are considered as ‘spent’ source rocks except from one sample showing fair petroleum potential and immature organic matter. A new potential source rock was discovered at the base of the Jurassic sequence showing very high amounts of TOC wt.% Type I/II immature organic matter with a ver y high remaining hydrocarbon potential. Oligocene-Miocene clastics show generally low TOC values with low gas potential, whereas contain very sparce, cm-thick organic-rich and oil-prone seams.

Carbonate reservoirs in the Greater Mediterranean are associated within a wide range of different platform settings, from mixed evaporite-carbonate epeiric platforms, to isolated platforms and reef systems.

In this work we present a new classification scheme based on literature review of 60 commercially exploited carbonate reservoirs. The classification is based on 1) control on poroperm system: diagenetic vs depositional; 2) Gross depositional environment; 3) carbonate factory type. 11 different reservoir types are identified on these bases and their distribution has been mapped out by the location of Mediterranean hydrocarbon fields in which the reservoirs are exploited.

The review highlights the limitations of the “reef” paradigm for understanding carbonate reservoirs in the study area and highlights the need for exploitation strategies to be based on depositional models that are appropriate to the “carbonate factory” of interest.

The classification scheme and associated database are intended for use during both the exploration phase of a project, and the appraisal/ development stage. It provides a tool to select appropriate depositional and diagenetic models, to understand the range of properties associated with different reservoir types and select analogues.

This study aims to investigate the presence of Cretaceous carbonate platform facies on the island of Kephalonia, which was previously thought to belong entirely to Pre-Apulian slope domains. Such presence may have a deep impact on the regional oil and gas exploration, since Mediterranean Cretaceous reefs have often proved to be excellent reservoir units (e.g., Zohr Field).

Micropalaeontologic, sedimentologic, microfacies and geochemical indicators all show that, on the westernmost part of the island, Campanian-age inner platform to platform margin facies are present (Area 1 or “Argostoli platform”), with a shift to progressively more distal time-equivalent Pre-Apulian units eastwards (Areas 2–4).

The Argostoli Platform, in western Kephalonia, is characterized by clear evidence of inner platform to platform margin facies, including possible peritidal cycles and redded palaeosol layers intercalated with thick-massive limestone beds, with above-background concentration of Fe2O3, Al2O3, TiO2, SiO2. In this area, microfacies are attributable to inner platform to platform edge, including wackestones/floatstones (FZ7, SMF9), grainstones- grapestones (FZ7, SMF 16, 17), oolitic rudstones/grainstones (FZ6, SMF15) and boundstones (FZ5, SMF7), with bryozoans, mollusks and miliolidae.

The Argostoli Platform may represent the easternmost edge of the Apulian Platform and may belong to the Apulian Domain rather than to transitional Pre-Apulian units.