Abstract: 3-D Seismic Reservoir Characterization for the Independent Producer, Sooner Unit, Weld County, Colorado

D. S. Singdahisen, M. T. Kramer, E. F. Jaynes

Geologic heterogeneity is known to be an important control on fluid flow in petroleum reservoirs. Interpretation of 3-D seismic data provides a technique for analysis of the spatial characterization of reservoir features and properties. In combination with detailed analysis of engineering and geologic field data, 3-D seismic can provide information on reservoir character on a scale not readily available from borehole information. Wellbores provide direct investigative reservoir data, but commonly at a scale (well spacing) greater than the scale of reservoir heterogeneity. 3-D seismic surveys provide a much greater sampling density of reservoir data (100 ft vs 40 acres). Integration. of these data sets is required to successfully characterize the reservoir.

As part of a DOE sponsored program on enhanced recovery in fluvial-deltaic reservoirs, a multidisciplinary reservoir characterization study of the Muddy `D' reservoir in the Sooner Unit of the Denver-Julesburg Basin has been undertaken. Reservoir characterization in the Sooner Unit has encompassed interpretation of 3-D seismic data, detailed stratigraphy- well log analysis, transient well testing, production flow testing, and reservoir flow simulation. Project goals include the identification of optimal infill drilling locations, relocation and optimization of injection patterns. and improved reservoir management through scheduling of production/withdrawal rates.

All seismic interpretation work on the approximately 7.7 sq mi Sooner Unit 3-D seismic survey was performed using the Schlumberger/GeoQuest Interactive Exploration System software package on an UNIX based Sun Sparc2 workstation platform. 2-D seismic modeling has shown that relative amplitude and instantaneous frequency can be used to delineate spatial variations in stratigraphic layer thickness. As a result, 3-D seismic attribute data can be used to delineate the lateral extent of potentially productive Muddy `D' reservoir. The relative magnitude of these attributes can be employed to characterize the relative thickness of geologic units and general reservoir properties.

3-D seismic data has become a valuable geophysical tool in applied reservoir characterization. 3-D seismic provides higher density sampling of reservoir heterogeneity than does conventional 2-D seismic or log data from standard well spacing. As a result, 3-D seismic commonly provides reservoir information that can not be observed or gathered by other means. When integrated with detailed geologic interpretation and reservoir engineering analysis, 3-D seismic reservoir characterization provides the necessary information to enhance reservoir description, develop more accurate reservoir models, reduce risk associated with project development, and provide improved reservoir management.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994