Journal of Petroleum Geology, vol. 20(4), October 1997, pp. 381-402
©Copyright 1997. Scientific Press, U.K. All rights reserved.
GEOCHEMISTRY OF LITHUANIAN OILS AND SOURCE ROCKS: A PRELIMINARY
ASSESSMENT
O. Zdanaviciute* and J. A. Bojesen
Koefoed**
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 of partly-exhausted source rocks within the
Cambrian succession. Furthermore, possible source rocks are present within the Ordovician
succession, and excellent source rocks occur within the Silurian in several wells. 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 and maturation took place in the latest Palaeozoic. The most
important reservoir rocks are Middle Cambrian sandstones, but petroleum accumulations also
occur in Ordovician limestones and Silurian reefal carbonates. Petroleum accumulations in
Lithuania probably result from the pooling of oil derived from several sources, with the
Lower Silurian (Llandoverian) shales being the most important single contributor.
