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Three-Dimensional Reservoir and Simulation Modeling of Hyperpycnal Systems: A Case Study of LAG-3047, Block X, Misoa Formation, Maracaibo Basin, Venezuela

Helena Gamero1, Lucienne Laporte2, Jose Luis Perdomo1, Tami C. Rahn3, Christina Isakson3, and Freddy Rodriguez2
1 Schlumberger, Caracas, Venezuela
2 PDVSA Occidente, Maracaibo, Venezuela
3 Schlumberger, Houston, TX

The Eocene Misoa Formation is a prolific producer of hydrocarbons in the Maracaibo basin and traditionally has been interpreted as being deposited in a fluvio-deltaic depositional system. Sedimentological interpretation of 1,400 ft of core has led to the development of a new depositional model. The Misoa Formation has been reinterpreted as being deposited from sustained fluvial-derived hyperpycnal flows. The conceptual hyperpycnal model has been used to guide correlation of 21 wireline logs and to provide a high-resolution stratigraphic model of the Lower C Misoa Sands. A geostatistical approach was used to propagate the facies and the petrophysical properties in the geological model. However, some difficulties were encountered for propagating hyperpycnal channelized-lobe systems, since a standard object-modeling algorithm is useful only for fluvial systems. An alternative three-step methodology was developed to model channelized-lobe systems and proved to be very successful. Forty realizations of the geological model were generated to assess the uncertainty in the distribution of channelized-lobe systems between wells. An advanced software package was used to rank the realizations; the best realizations were chosen by historical pressure and production. Two upscaled grids were generated for simulation and prediction. The hyperpycnal depositional model aided in the simulation calibration process because reservoir compartments were easily modified to match the historical pressures and therefore connected reservoir pore volumes. At the end of the calibration process, these reservoir compartments could be used to define whether new wells would be likely to contribute to the proposed waterflood or to access new reservoir pools.