3D Geological Modeling of a Karstified Carbonate Reservoir Supported on Seismic Attributes and Dynamic Well Data, Campos Basin, Brazil
A. Correa, Carolina R.1; Lykawka, Ricardo; A. Lourenço, Augusto T.; da Silva, Adriana P.; Reis, Felipe N.; and Leviski, Tiago F.
The main purpose of this paper is to present an integrated approach for the 3D geological modeling of an Oligocene-Miocene, karstified red algae-rich carbonate reservoir from Campos Basin, Brazil. The integration of seismic attributes extracted from high-resolution seismic data, wells logs from 24 wells, and continuous core data allowed the definition of the highstand systems tracts of four 3rd order stratigraphic sequences, mapped as clinoform sets in the amplitude seismic data. These sequences are mostly composed of red algae-rich wackestones, packstones, rudstones and bindstones, which comprise different facies associations in backreef, reef and forereef settings. Zones of vuggy carbonate facies with very high porosity (> 40%) and permeability (>50D) were recognized in cores, well logs, and mainly from an extended well test (EWT). These zones are interpreted as a product of epigenetic karstification processes. Clinoform geometries and the respective facies distribution in the different platform settings guided the modeling of the distribution of the reservoir porosities and permeabilities. The higher- permeability karstified zones were initially modeled as layers containing high proportion of vuggy facies located on the top boundary of each 3rd order clinoforms sets. These facies were interpreted as produced by dissolution by meteoric fluids along subaerial unconformities. However, the analysis of EWT data integrated with seismic amplitude attributes showed that the karstification process was associated not only to subaerial exposure, but also to sub-vertical fracture corridors. These sub-vertical very high-permeability karstic zones were incorporated into 3D geological models by using a value range discretization of the seismic amplitude variance data until an adjustment with the EWT bottom well pressure and water production data was obtained.
AAPG Search and Discovery Article #90166©2013 AAPG International Conference & Exhibition, Cartagena, Colombia, 8-11 September 2013