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Estimation of Petrophysical Parameters and Stratigraphy of Thin Reservoir Sand from Seismic Lithologic Modeling

Marc De Buyl, Tom Guidish

Reservoir description away from well control can be improved by supplementing wire-line log and core data by petrophysical parameters estimated with seismic lithologic modeling techniques.

Two independent reservoir models were constructed for an oil-bearing channel-sand reservoir in the Taber-Turin area, Alberta, Canada. The first reservoir description was based solely on log and core data from six producing and two dry wells drilled within a portion of the field on which a 3-D seismic survey was acquired. The second reservoir model was supplemented by petrophysical parameters derived from Seismic Lithologic Modeling (SLIM) of the 3-D seismic reflection data.

A detailed model of the stratigraphically complex reservoir was constructed using the results of a forward lithologic parameter estimation process that produces a thin-layer solution from the band-limited, noise-contaminated seismic data.

Based on the model results, and after calibration with log and core data, maps of reservoir thickness, porosity, and permeability are produced. Crossplots of seismically inferred parameters versus core-calibrated log interpretations exhibit a limited scatter in the data which, in turn, testifies to the accuracy of the seismic reservoir characterization. The improved accuracy in predicting reservoir variation attained by incorporating seismic control is also demonstrated by comparing the projections from the two separate models with the actual values observed at two new well locations that were not included in the modeling.

The increased detail and confidence in reservoir description provided by the information obtained from Seismic Lithologic Modeling of 3-D survey data can dramatically reduce risk (cost) in field development programs, improve results of model simulation and, in turn, enhance reservoir management.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.