Topseal Development within the Mesozoic-Cenozoic Carbonate Successions of the Greater Mediterranean

Mediterranean Mesozoic and lower Cenozoic Carbonate successions host prolific petroleum systems that are the focus of ongoing exploration activity, particularly in Greece and the Levant Basin. These thick carbonate sequences were initiated during the early phases of the development of the Tethys Ocean and range from Triassic to Eocene age. They include sediments deposited within epeiric and isolated carbonate platforms and in deepwater basins.

The reservoir and source rock units within many of these petroleum systems are an integral part of the carbonate succession. In contrast, seals are mainly younger clastic sediments or Messinian evaporites overlying the carbonate edifices. However, proven seals do occur within the carbonate sequence and this contribution aims to review their occurrence from the perspective of regional geology. Most intra-carbonate seals are evaporites deposited in sabkha/ lagoonal environments or shelfal carbonate mudstones deposited across shallow marine carbonate domains during drowning events of varying durations. Secondary intra-carbonate seals are fine grained carbonates deposited in either deepwater or intra platform basins. An appreciation of these intra-carbonate seals may serve to unlock deeper hydrocarbon potential and may also be of relevance to energy transition technologies, such as CCS, as these mature and are deployed across the region.