SHALE GAS POTENTIAL OF THE ROMANIAN PLATFORM UNITS

Potentially gas bearing shales and argillites are connected to the foreland Carpathians, in the platform units, at depth exceeding 2500–3000 m (south of M oldavian Platform, Scythian Platform (Bârlad Depression), and Moesian Platform with its extension in South Dobrogea. The formations developed in the sediment dump of the Moldavian Platform, containing sequences of clay rocks which are richer in organic matter and implicitly those of gas shale (GS) type, are bituminous argillites and black clay rocks from the Paleozoic (Vendian – Silurian Period). Black clay formation from the M iddle Silurian exists at depths of 400–2300 m, was deposited under accumulation conditions corresponding to a dysoxic-anoxic marginal basin and its thickness exceeds 30–40 m. TOC values (0.35 and 1.6) and vitrinite reflectance (Ro between 0.35 and 1.6), reveal a remarkable potential. Bârlad Depression, which is part of the Scythian Platform, has formations of particular concern for shale gas production, dating back to the Silurian – Devonian sedimentation cycle. The relevant formations developed at depths between 900 and 3800 m, in a basinal-pelagic depositional environment, and the organogenetic parameters have average values between 1.0 % and 2.4 % for TOC and between 0.60 % and 3.5 % for vitrinite reflectance. Upper Cambrian – Westphalian, Permian – Triasic and Toarcian – Senonian cycles from the four sedimentation cycles of Moesian Platform overlay have an important shale gas potential. The main formations with a proven gas production potential are Ţăndărei Clay Formation, Călărasi Formation, Vlasin Formation and Bals Formation where of Silurian formations in the graptolite argillite facies have the most important shale gas generation potential (TOC = 1.0–1.9%, Ro = 0.40–1.40%).