Computer-aided maturity modelling predict hydrocarbon generation history of unrecovered formations in Dolna Kamchija region, Western Black Sea Basin

Abstract

The personal computer-aided basin modelling system (MAT 98) was applied to predict maturation and oil generation history of formations in areas at early stage of exploration in Dolna Kamchija region – Paleogene sequence in the Black Sea shelf zone and Mesozoic sequence offshore (borehole R-64, Longoza). The sequences represent different stages in development of the basin, providing good examples to show the importance of temperature history for the prediction of hydrocarbon generation history. Ten alternative burial histories, thermal histories and oil generation histories models are also demonstrated in order to evaluate the influence of possible errors on the predictions. Results suggest that Jurassic – Valanginian formations onshore had attained sufficient maturation during Early Cretaceous time with corresponding paleotemperatures of 130 to 180° C. The possible primary migration from these formations is also discussed. Present day oil generation zone onshore is evaluated to be located in a depth interval 2250 to 3250 m, including a part of Malm – Valanginian complex and Upper Cretaceous formation. In the offshore area of Dolna Kamchija depression, present day maturity levels of Paleogene formations are evaluated to be in the range 0.5 to 0.8 % Ro corresponding to an initial stage of oil generation. The present day oil generation zone offshore is suggested to be located at depths more than 3000 to 4000 m and mainly to comprise Cretaceous sequence. The Mesozoic formations onshore and offshore in Dolna Kamchija region are the most important petroleum source rocks which have sufficiently matured to generate hydrocarbons.