engleski

Dinarides, still unexplored opportunities

Petroleum exploration in the Dinarides has been carried out from 60’ to 80’ of the last century, encouraged by widespread occurrence of oil seeps and bituminous rocks. Despite 22 drilled wells no discoveries have yet been made, mostly because of structural complexity and lithological uniformity (carbonates) which limit seismic quality. Source potential (TOC, pyrolysis and kerogen type analysis) exists in Upper Permian (20% TOC, Type II oil-prone kerogen, post-mature), Middle Triassic (Type II oil-prone kerogen, late-mature), Upper Jurassic (about 10% TOC Type I/II oil-prone kerogen early-mature) and Upper Cretaceous (Type I oil-prone kerogen, low-mature to immature). The maturity studies have shown that Permian to Late Jurassic source rocks attained their maximum burial conditions/migration prior to Eocene main compression phase and Miocene relaxation. The originally trapped hydrocarbons escaped either by faulting or tilting of the structures. There is a little chance to locate original traps with negligible spillage. However, the perception of migration and entrapment history combined with play concepts (reservoirs and seals) leads to designation of two most prospective exploration zones in the Dinarides: a) imbricated thrust series in “ shallow” external zone (coastal Croatia), which are stacked at their tops and merging with the sole fault at the bases and b) subthrust structures, as footwall anticlines and duplexes, of interior part of the External Dinarides thrust (south-western Bosnia and Hercegovina).

Dinarides; petroleum exploration; coastal Croatia; source potential

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