--> Abstract: Definition of Stratigraphic Traps in Exploration Using Stochastic Models and Seismic Multi-Attributes, by Miguel Nunez, Jesus M. Rodriguez, Saileth Cortez, Orlando Parra, Marcos Romero, and Alejandro Salas; #90039 (2005)

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Definition of Stratigraphic Traps in Exploration Using Stochastic Models and Seismic Multi-Attributes

Miguel Nuñez1, Jesús M. Rodríguez1, Saileth Cortez2, Orlando Parra2, Marcos Romero2, and Alejandro Salas2
1 PDVSA E & P, Maracaibo, Estado Zulia, Venezuela
2 PDVSA E&P, Maracaibo, Venezuela

The exploratory prospect Horcon is located between Barua and Motatan structural highs in the Maracaibo Basin. The prospect is defined as a stratigraphic trap. The targets to evaluate are the lower sands of Paují Formation and the upper “B” sands of Misoa Formation from middle Eocene.

This trap was observed as an RMS amplitude anomaly of high values. But the uncertainty was high because it is located in a dip south synclinal. Using data from near oilfields and defining electrofacies (Core & Well Log) we built a stochastic sedimentological model that led us to interpreted a coastal-transitional environment, with presence of different deposits and facies: off-shore, littoral bars, barrier islands and tidal channels.

To improve the trap visualization, seismic attributes were used to extrapolate this information (stochastic model) and obtain a relationship between them. After that, the “wave forms” (classes) were derivate from different instant attributes, previously calculated, that represent the seismic data (Dip, Third and Second Derivate, Phase Cosine). Finally, the seismic volume response was correlate with the seismic-facies maps generated, and then they were calibrated with the static model, obtaining and excellent correlation and integration.

The combination of seismic-facies and other attributes allowed us to observe rock quality lateral changes, possible tide channels and deltaic lobes, that correlate with the depositional environments interpreted, and a truncation that was observed toward north of the prospect where the rock quality degrades.

Finally this seismic attributes and the static model correlation help to define all the exploratory prospect limits accurately.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005