Exploring Gravitary Carbonates in the Tethys domain: Geological Assessment and Application to the Arabian Carbonate Systems

Jean Borgomano¹, Cecile Pabian-Goyeneche¹, and Jérome Sirgue¹

Abstract

Gravitary Carbonates (GC) consist of carbonate sediments, formed mainly in shallow marine conditions and transported by gravity-related processes in slope-to-basin environments. They include a large spectrum of sedimentary systems from mass transports, debrites, high and low density turbidites that can build different types of carbonate bodies including lobes, channels, fans and aprons of variable dimension and complexity. Compared to siliciclastic submarine fans, which are found tens of sedimentary basins and produce hydrocarbon from hundreds fields , GC form hydrocarbon reservoirs in less than 10 petroleum provinces and are not generally identified by the industry as a high potential play. One of the most prominent GC producing fields (Poza Rica, Mexico) represents the typical carbonate systems which are developed along the Tethys continental margins during the Jurassic-Cretaceous: highly prolific “tropical” carbonate factories constructing flat-topped platforms and exporting significant volume of granular materials to deeper adjacent basins, where the GC reservoirs/traps are developed. Similar trend has been recognized along the Apulian margin (outcrop-susbsurface), where one significant oil discovery has been made offshore Adriatic in a Cretaceous base-of-slope bioclastic apron, the Aquila Field in offshore South Adriatic , Italy. More than the reservoir’s petrophysics, the main risks when exploring this kind of stratigraphic- type reservoir remains the trap geometry definition, the sealing behavior assessment and the hydrocarbons column prediction. An exhaustive analysis of such GC examples along the Tethys continental margins, provide the basis for unraveling the main controlling factors of the GC petroleum systems: reservoir development, trapping mechanism, relation to source rocks and access to hydrocarbon charge. A key step is to estimate the GC intrinsic and extrinsic parameters that control the petroleum systems. This approach allows the definition of geological rules which can be applied to the Arabian carbonate systems developed on the same geodynamic/climatic context, the Tethys continental margins. GC hydrocarbon potential on the Arabian margins is generally not considered by the industry, despite proven occurrences of Jurassic-Cretaceous GC systems on outcrops and subsurface. A comparative analysis of Tethys GC systems is proposed in the perspective of the hydrocarbon exploration assessment.

AAPG Search and Discovery Article #90188 ©GEO-2014, 11th Middle East Geosciences Conference and Exhibition, 10-12 March 2014, Manama, Bahrain