Reservoir Potential of Cretaceous - Tertiary Redeposited Deep-water Carbonates: A Core and Outcrop Study in the Apennines and the Adriatic Sea, Italy.

Redeposition of deep-water carbonates is poorly understood. As a consequence, quantifying their reservoir potential for hydrocarbon becomes extremely challenging. As such, this study aims provide a robust assessment of reservoir potential from Cretaceous – Tertiary redeposited deep-water carbonates. A comprehensive sedimentological description and petrophysical characterization includes sonic velocity, porosity and permeability from basinal samples adjacent to Adriatic carbonate platforms. The samples were collected from three areas; (1) Maiella platform margin, an isolated Mesozoic to Mid-Tertiary carbonate platform (2) Monte Conero, an isolated anticline of the distal section of the turbidite facies (3) Well 1, an offshore well in the Adriatic sea, which represents the subsurface analog of the basinal sediments in the Apennines. The redeposited deep-water carbonates are comprised of: breccias, turbidites, slumps, and blocks, contained in fine-grained background sediments. Analysis shows that breccias and calciturbidites are the two dominant redeposited deep-water carbonates facies. They are the thickest and the most common facies in both core and in outcrop. For the three locations, the Maiella deposits tend to be coarser and thicker compared to the others, which indicates that Maiella is situated in the proximal part of the basin. The petrophysical measurements from the three study sites exhibit a remarkably wide scatter in the data. The petrophysical measurements from the three study sites feature a wide range of data distribution. Overall, the petrophysical datasets show that Cretaceous breccias and calciturbidites from the Maiella are the most porous and permeable facies compared to similar facies from the Monte Conero and Well 1. The maximum porosity of the Maiella breccias and calciturbidites can reach up to 30.27% and 32.01%, respectively. The maximum permeability can reach up to 522.1 md for the Cretaceous calciturbidites and 129.151 md for the Cretaceous breccias. Velocity measurement shows that at any given porosity, the samples from Monte Conero and Maiella are the faster compared to Well 1. The maximum velocity of Monte Conero and Maiella samples reach 6554.38 m/s and 6325 m/s respectively and sit above the Wyllie’s time average line and create a positive deviation from the line. In addition to porosity and velocity, the influence of pore geometry to velocity and permeability of redeposited deep-water carbonates shown that the samples with the bigger and simpler pores (larger DomSize number and smaller PoA number) tend to have a higher velocity and permeability value, whereas, samples with the smaller and complicated pores tend to have a lower velocity and permeability value. Petrophysical data of redeposited deep-water carbonates demonstrate that these deposits have good potential as hydrocarbon reservoir’s thick, porous, and permeable. Furthermore, the juxtaposition of the redeposited beds with the background sediments would form an excellent stratigraphic trap and/or seal