--> 3-D Visualization and Geological Analysis of Deepwater Geobodies, Potiguar Basin (Offshore, NE Brazil)

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3-D Visualization and Geological Analysis of Deepwater Geobodies, Potiguar Basin (Offshore, NE Brazil)

Abstract

Abstract

This study was carried out in order to individualize turbidites within deepwater channel systems by applying 3D seismic capture techniques for identifying geobodies as well as spectral decomposition. Then, the results were analyzed using a sequence stratigraphic approach seeking a better characterization of the reservoir types present in the area.

The study area was the offshore portion of the Potiguar Basin, located in the easternmost part of the Brazilian Equatorial Margin. The chronostratigraphic interval studied comprises rocks from the Miocene until the recent.

A vintage full-stack seismic cube was used for the execution of this study in a way that was possible to generate two different kinds of products.

The first product successfully isolated geobodies that may represent potential reservoirs. For doing that, three steps were performed: identification, isolation and extraction. In the first step RMS amplitude anomalies were identified which represent geological features. The body isolation step was based in the definition of a range of anomalies which represent the identified geobodies. Then opacity and transparency values were applied for all other amplitudes which values fall outside that range. The last step performed included the use of the variance attribute which superimposed a relief texture to the geobodies.

The second product generated aimed to represent detailed geological features present in the chronostratigraphic interval studied by using the spectral decomposition technique.

This technique has provided the identification of two main types of turbidites systems in the analyzed interval: linear channels on the base and meandering channels on the top. These two systems were well highlighted through the geobodies which were defined by the application of the RMS amplitude attribute. A “cut and fill” relationship as well as a lateral and vertical migration of the identified channels indicated that there is potential for the presence of reservoirs in both channel types identified.

By-pass zones and absence of good quality reservoirs are by-products of the application of the spectral decomposition analysis.

This work has shown that visualization techniques are powerful tools in the geological/geophysical interpretation of turbidite systems, allowing a better definition of potential leads and risk assessment of reservoirs.