Migration Models, So Many to Choose! A Comparative Study from the Ogaden Basin of Ethiopia

Puteri Maizura Razali and Peter Abolins
Technical Geoscience, Petronas Carigali Sdn. Bhd., Kuala Lumpur, Malaysia

As explorationists, we are tasked with finding new hydrocarbon reserves. As an aid to this, basin modeling has become increasingly ingrained into exploration workflows. As powerful hardware becomes more common place, software developers are providing us with more features, specifically with regards to hydrocarbon migration.

This paper investigates the differences that were observed when four different migration methods were applied to the same 2-D and 3-D basin models. The four migration methods studied were (i) Darcy, (ii) invasion percolation, (iii) flow path and (iv) a hybrid of Darcy and flow path.

The project was carried out as a 3-D model constructed for the Ogaden Basin of Ethiopia. Subsequently, 2-D models were extracted from this. Considering the size of the study area, only regional scale differences were investigated.

The Ogaden Basin has undergone at least two extensional phases, the Permo-Triassic and Tertiary rifts, developing a lacustrine depositional system, partially filled by the proven Calub reservoir sand. The substantial tectonic evolution of the basin promotes high heat flows, influencing the maturity of two main regional source rocks; these are the Triassic Bokh formation (lacustrine) and the Upper Jurassic Uarandab formation (marine). Appropriate kinetics and organic richnesses for these source rocks were incorporate into the model.

At a software level, considerable variation was observed in the run time required to complete each simulation. On a geological level, the four different methods produced noticeable differences in terms of oil and gas distribution, and volumes accumulated. These differences are discussed.

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