Print this pageThe Eocene Carbonate System(s) of the Sirte Basin, Libya: Implications of Regional-Scale Observations
Uwe P. Baaske1, Jimmy Van Itterbeeck2, Helena Griffiths2, Paul Tricker1, Mohammed Mugheiry1, and Peter Burgess1
1Shell International Exploration and Production B.V., Rijswijk, Netherlands
2Shell Exploration and Production Libya GmbH, Tripoli, Libya.
The Eocene section of the Sirte Basin in Libya is characterized by extensive carbonate systems that house economically significant hydrocarbon plays. These plays focus on reservoirs located within a platform with the assumption that reservoir quality deteriorates in more distal, i.e. deeper water, areas. However, newly acquired regional 2D and 3D datasets allow development of more detailed understanding of the architectures and facies evolution of the carbonates, aiding development of new exploration concepts and new plays outside the proven. Based on seismic observations, and constrained with well information, we offer a more differentiated view on the Eocene carbonate systems and look to identify areas of under-explored and speculative prospectivity.
The main part of the Eocene in the Sirte Basin accumulated as a large-scale ramp system. Changes in available accommodation and antecedent tectonic elements modified the geometry of the ramp setting in space and time, leading to a more complex carbonate system architecture and hence more complex reservoir distributions.
The western and central parts of the Eocene carbonate systems were dominated from the early until the late middle Eocene by ramp architectures with wide depositional facies belts. However, the isochronous eastern part of the carbonate system, along the western Cyrenaica Terrace, has a flat-top platform architecture at this time probably due to tectonic influence on platform margin stacking. During the late middle Eocene changes in distribution of subsidence and perhaps also carbonate production created a flat-top platform architecture across the whole basin.
Based on this model, there is the potential to target new, speculative prospectivity in the Sirte Basin. New understanding of facies belt distribution derived from this model can also potentially be applied to other carbonate systems in other basins.
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