Investigation of gas and gas hydrate accumulations in the Western Black Sea continental slope

In order to investigate gas and gas hydrate accumulations in the Western Black Sea continental slope, approximately 355 kilometer of high resolution multichannel seismic data was collected in 2008. The data was processed using conventional processing flows. Anomalous reflections of gas accumulations were determined on the final migrated sections using seismic attribute analysis (instantaneous polarity, phase and frequency as well as reflection strength). Distribution of shallow gas accumulations was mapped along the study area. Shallow gas accumulations have generally been determined under the ridge structures forming anticline-type formations. Normal faults were generally observed below these structures. It is concluded that the gas produced from deeper sediments migrates into the shallower sediments along these fault planes. A conceptual model indicating this fault-related gas migration and trapping were produced. Shallow gas accumulations are generally 40-510 millisecond below the seabed, and the high amplitude reflections from top of these reservoirs are distinguished by their distinctive negative polarity.A Bottom Simulating Reflection (BSR) indicating gas hydrate formations was also observed in a limited area. A shallow reef structure was also observed in the area with gas related structures. A new model for the formation of this reef struture and fluid migration in the sediments below the reef was introduced. Furthermore, in order to define the general stratigraphic framework of the study area, Miocene, Pliocene and Quternary interfaces were picked on the final seismic sections, and depth and thickness maps for Pliocene and Miocene times were computed.