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Using Geophysical Well Logs to Estimate the Porosity System of Albian Carbonates of Campos Basin - Rio de Janeiro
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 78th EAGE Conference and Exhibition 2016, May 2016, Volume 2016, p.1 - 5
Abstract
Summary
Albian carbonates are important oil reservoirs on the NE coast of Rio de Janeiro. In this work, aiming to evaluate the porosity of these deposits, we used basic well logs, geological information and petrophysical laboratory data from two oil fields of this region. However, proposed models to study this kind of reservoirs consider combinations of porosities derived from density and neutron logs, but do not recognize the importance of sonic porosity in the identification of fractures that distort the porosity models when they are compared with experimental data. Still, joint analysis of porosities derived from these three logs is addressed in this study and a new regression is proposed, which showed high correlation with the petrophysical data in both fields, regardless the differences of diagenetic processes that every oil field was submitted. Furthermore, the linear regression model applied to the calculation of Archie’s cementation coefficient (m) demonstrated that in zones with not connected porosity the value of m will be greatly increased and should not to be considered to calculate the saturation. Finally, using porosity cross plots derived from density and sonic logs allowed to identify different kind of porosities and to visualize the effective porosity along the geological formations.
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