Geologiczne uwarunkowania identyfikacji perspektywicznych struktur wodonośnych dla składowania gazu zmiennego i CO2 w n-e Bułgarii

Metodykę oparto na ocenie kryteriów litologicznych, strukturalno-tektonicznych, sejsmotektonicznych, hydrogeologiczncyh, petrofizycznych, termicznych i ciśnieniowych. Zastosowano ją dla identyfikacji struktur wodonośnych perspektywicznych z punktu widzenia składowania gazu ziemnego i C02, na terenie północno-wschodniej Bułgarii. Zidentyfikowano i oceniono warunki geologiczne składowania dla poziomów wodonośnych, reprezentujących struktury od dewonu po górny ocean, leżących w zasięgu Monokliny Warny, obniżenia Dolnej Kamczy, wyniesienia północnobułgarskiego i obniżenia Aleksandrii. Głębokość występowania stwierdzonych poziomów waha się od 500 do 1700 m.

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The methodical approaches for identifying of perspective aquifer structures for natural gas and C02 storage indicated by the authors in previous works are applied for a part of North-Eastern Bulgaria. They are based on the main requirements for the suitability of the geological sites and are connected to preconditions ensuring lithologic, structural-tectonic, seismotectonic, hydrogeological; petrophysical, termobaric and other requirements. The regional reservoir systems defined for Northern Bulgaria are examined in the Phanerozoic section of the studied territory. They are characterized by specific lithological features and development and are of great interest for the natural gas and C02 storage. The structural-tectonic conditions in the Moesian Platform (The Varna Monocline, The North Bulgarian Uplift and The Alexandria Depression) and the Dolna Kamchia Depression determine the presence of different geological structures. Different types of natural traps are bounded to them. Some of these traps correspond to the requirements for natural gas and C02 storage. The seismic and neotectonic situation is variable (basically low to middle and in rare cases higher), which determines different earthquake activity and behavior of the fault breaks in the neotectonic development of the territory. The natural reservoir connected to the Upper Jurassic - Lower Cretaceous permeable complex, in spite of its high capacity and filtration potential, contains fresh water with active hydrodynamic regime and this fact makes it unsuitable for natural gas and C02 storage. The defined reservoir systems and sealing formations are characterized by too different structure and petrophysical properties and this influences their suitability of the natural traps natural gas and C02 storage. Perspective structures for natural gas and C02 storage, connected to Devonian, Triassic, Middle Jurassic and Paleogene reservoir systems, are registered on the basis of the geological conditions' analysis and the criteria parameters in the Phanerozoic section of the studied territory.