Publications

Finding good carbonate reservoirs is always a promising yet challenging endeavor. Recently, the search for new carbonate plays in Indonesia has led to the search for grainy shallow water carbonates re-deposited into the deep water areas surrounding the isolated carbonate platforms. These include carbonate mass gravity flows, turbidites and others hereafter called redeposited deep-water carbonates. These deposits are relatively easy to identify where there is good seismic data but it has been traditionally difficult to define the traps and the creation / preservation of porosity. Consequently, the number wells drilled to target from this type of play is relatively small and the number of oil and gas fields discovered from it is also small. As a result, redeposited deep-water carbonates are not well understood due to very limited resources and the rarity of hydrocarbon production from these deposits. This study provides a thorough assessment of analogous outcrop in the Apennines and a core from the coeval slope and basinal facies in the Adriatic offshore, Italy. The study includes sedimentological and petrophysical characterization of redeposited deep-water carbonates and their background sediment from the outcrop samples. In both the outcrop and subsurface areas, four redeposited deep-water carbonates facies occur in periplatform background sediment. These facies include debris flow breccias, turbidites, slumps and calcisiltite. Debris flow breccias and turbidites are the most porous and permeable rocks compared to the other facies. In addition to that, at the same porosity, both redeposited deep-water carbonates from both Cretaceous and Tertiary section are more permeable compared to the background sediments. Porosity of Cretaceous breccias and turbidites is up to 32% and permeability can reach 522 mD. Similar to the Cretaceous breccias and turbidite, the porosity of Tertiary breccias and turbidites is up to 30% and permeability reaches a maximum of 283 mD. Both breccias and turbidites from the Cretaceous and Tertiary can have a good porosity and permeability. Additionally, most of Tertiary breccias and turbidites tend to have lower permeability compare to Cretaceous breccias and turbidites. The porosity and permeability of the redeposited carbonares is related to its original mineralogy and the diagenetic processes. During the Cretaceous, calcite is the predominant carbonate mineral precipitating in the world’s oceans, while in the Tertiary most carbonate production is aragonite. The less stable aragonite has a high diagenetic potential and is subject to dissolution and re-precipitation. This process can produces a tight rock, or a more porous and permeable rock. In the studied Tertiary samples diagenetic processes produces a tight permeability (less than < 1 md) rocks, however, some rocks with good permeability were also observed. In summary, petrophysical data demonstrate that redeposited deep-water carbonates have potential to be hydrocarbon reservoirs because they consist of thick, porous, and permeable rocks which creates favorable conditions for exploration.