Title: Basin modelling study of potential source rock formations in North Ionian Sea
Τίτλος: Μοντελοποίηση ενδυνάμει μητρικών σχηματισμών πετρελαίου στο Βόρειο Ιόνιο Πέλαγος
Πασαδάκης Νικόλαος, Καθηγητής ΜΗΧΟΠ (Επιβλέπων)
This study will focus on the basin modeling of potential source rock formations in western Greece. Its main purpose is to evaluate the potential source rock formations in two wells within the Ionian basin using PetroMod (version 2017.1) software. The first one is the Agios Georgios-3, an onshore well in Epirus area. The second one is the offshore East Erikoussa-1 well drilled to the east of the island Ereikoussa (part of the Diapontia Islands complex) in the northern Ionian Sea. The main goal of 1D basin modeling is to simulate the basin evolution (burial history, thermal history, maturity history, potential hydrocarbon generation, expulsion). The 1D basin modeling software was used to reconstruct the temperature and maturity histories of the formations penetrated by the studied wells, giving attention to the maturity, transformation ratio (TR) and hydrocarbon potential generation of the source rock formations. In addition, a sensitivity analysis using various scenarios was conducted for the Agios Georgios-3 well in order to monitor the influence of erosion thickness and boundary conditions and to assess the results.
In Agios Georgios-3 well three source rock formations were identified of different stratigraphic levels (the Posidonia shales of Jurassic age, the Vigla shales A and the Vigla shales B, both of Cretaceous age). Posidonia shales is the most mature source rock formation of this well. Despite references in the literature on the extensive dolomitization in the area, a fact that may have seriously affected this source rock, our model showed that Posidonia shales presented the highest transformation ratio and potential oil and gas generation masses of all source rock formations of this well. Vigla formation developed very good quality hydrocarbon source rocks as well. It consists of two main source rock formation zones, Vigla shales A (upper horizon) and Vigla shales B (lower horizon). The second one (older) is more mature than the first, with higher transformation ratio and potential hydrocarbon generation mass than the other.
In East Erikoussa-1 well only one source rock formation (the Vigla shales) was identified. The transformation ratio and potential oil and gas generation masses of Vigla are very low, indicating an immature source rock formation.
Our models provided that neither of the two studied wells reached the peak oil expulsion in the specific areas although the Posidonia shales show to be more mature with higher transformation ratio than the Vigla source rocks in the Agios Georgios-3 well.
Sensitivity analysis applied on the Agios Georgios-3 well, due to the fold and thrust belt (FTB) of the western Hellenides, which is affecting the well area. Results displayed that the thickness of eroded surface at 0m depth affects positively the transformation ratio values and potential hydrocarbon generation mass values of the source rock formations, with standard heat flow. It is also shown that among the boundary condition parameters which applied, only the heat flow plays an important role to the temperature and maturity modeling.