Análogos de reservatórios de rampa de água profunda: sistemas ricos em lama (unidade de Apiúna-SC) e em areia (Formação Punta Negra, Pré-Cordilheira Argentina)

Abstract

Two main reasons justify the use of outcrops in petroleum geology. The former, almost obvious, is related to the outcrop study in sedimentary successions with potential hydrocarbon exploration. The second is the production of models of geometric reservoirs distribution. In this work we consider two deepwater system models generated from outcrop analysis. A mud-rich deepwater ramp and a sand-rich deepwater ramp, represented, respectively by: i) Apiuna Unit, pre- Cambrian, Santa Catarina State and ii) Punta Negra Formation, Devonian, Argentine Precordillera. The Apiuna Unit is 4,500 m thick mainly constituted by laminates mudstones crosscut by channel and sheet sand systems, irregularly distributed. The Punta Negra Formation is characterized by the predominance of sandy deposits, originated in long unconfined sand sheet bodies with a wedge geometry crosscut by confined sandstones. The presence of various channelized bedforms oriented approximately in the same direction, in an extensive area of 250 km, suggests a multiple sedimentary input ramp system to this unit. The depositional architecture reconstruction shows that in sand-rich systems the dimension, petrophysical properties and connectivity of the sandstones construct better potential reservoirs. The reservoir quality and distribution in mud-rich ramp systems show more risks in oil exploration. However, differently than mud-rich systems, the sand-rich systems does not have sealing rocks.