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A High-resolution Facies Model of Pre-salt Lacustrine Carbonates Reservoirs. Morro do Chaves Fm. Example, Brazil
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 78th EAGE Conference and Exhibition 2016, May 2016, Volume 2016, p.1 - 5
Abstract
Barremian lacustrine carbonates, essentially coquinas, are the reservoir rocks of the large pre-salt petroleum findings in deep to ultra--deep waters of Santos, Campos and Espirito Santo basins. The complicated geological setting of those discoveries, with the massive overburden of salt bodies, makes the seismic imaging of the carbonate reservoirs an expensive and challenging matter. In this setting, accurate facies models are a demand for the predictability of the carbonate reservoir intervals.
This work shows an analogue high-resolution coquinas facies model based on an interpretation of a pseudo--3--D Ground Penetrating Radar (GPR) survey. We rely not only on the trace amplitude analysis but mainly on trace attributes to diminish the ambiguity of the interpretation due to potential visual biases. We have used the dip and texture attributes to help us better understand the subsurface and to focus on the main stratigraphic features of the reservoir analogue. Then we have produced a joint interpretation, based on three trace attributes: i.e., amplitude, dip and texture to highlight the main radar facies. That resulted in a facies model in which three SW-NE striking coquina bars (reservoir facies), correlated with transgressive systems tract (TST) interbedded with shales (nonreservoir facies) of highstand systems tract (HST), are identified.