O. Zdanaviciute et Ja. Bojesenkoefoed, GEOCHEMISTRY OF LITHUANIAN OILS AND SOURCE ROCKS - A PRELIMINARY ASSESSMENT, Journal of petroleum geology, 20(4), 1997, pp. 381-402
A series of oils and potential petroleum source-rock samples has been
analysed from exploration wells on-and offshore Lithuania. Despite the
limited amount of data, the results indicate the possible existence o
f partly-exhausted source rocks within the Cambrian succession. Furthe
rmore, possible source rocks are present within the Ordovician success
ion, and excellent source rocks occur within the Silurian in several w
ells. The source rocks are all present within a few hundred metres of
stratigraphic succession and the thermal maturity roughly follows the
actual depth of burial, despite the fact that most of the subsidence a
nd maturation took place in the latest Palaeozoic. The most important
reservoir rocks are Middle Cambrian sandstones, but petroleum accumula
tions also occur in Ordovician limestones and Silurian reefal carbonat
es. Petroleum accumulations in Lithuania probably result from the pool
ing of oil derived from several sources, with the Lower Silurian (Llan
doverian) shales being the most important single contributor.