Abstract: How Sequence Stratigraphy Impacts the Dynamic Modeling of By-passed Oil Accumulations in Two Upper Jurassic Carbonate Reservoirs, Berri Field, Saudi Arabia

HEIL, RICHARD, RICHARD PAVLAS and Members of the Berri Modeling Team,

In the mature stages of reservoir depletion, production of by-passed oil accumulations becomes a major concern. Reservoir simulation, used for evaluating development strategies, depends on a reservoir characterization that contains the spatial information necessary to predict the size and location of bypassed oil accumulations from production/injection rate data. The Hadriya and Hanifa reservoirs in Berri field, which have been on production for almost 25 years, illustrate the importance of proper geological modeling to reservoir characterization and, ultimately, successful exploitation of by-passed oil.

The impact of carbonate sedimentation on reservoir performance of the Hadriya and Hanifa reservoirs can be explained in a sequence stratigraphic framework. Both reservoirs are thick, high-stand systems tracts capped by thinner shelf-margin wedge and transgressive systems tracts of high permeability grainstones. Fluid flow in the Hadriya reservoir is controlled by depositional facies and diagenesis that both parallels and cross-cuts the depositional fabric. In the Hanifa reservoir, distribution of depositional facies and the inherent permeability contrasts between facies are the primary factors affecting reservoir performance.

Over the years, both reservoirs developed significant by-passed oil accumulations. These were predicted by reservoir simulation models using sequence-stratigraphy-based reservoir characterizations. Horizontal well drilling programs to recover this oil are being directed by analyses of simulation results.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria