Three-Dimensional Seismic Attributes Help Define Controls on Reservoir Development: Case Study from the Red River Formation, Williston Basin
R. A. Pearson, B. S. Hart, 2004. "Three-Dimensional Seismic Attributes Help Define Controls on Reservoir Development: Case Study from the Red River Formation, Williston Basin", Seismic Imaging of Carbonate Reservoirs and Systems, Gregor P. Eberli, Jose Luis Masaferro, J. F. “Rick” Sarg
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The use of three-dimensional (3-D) seismic attributes to predict reservoir properties is becoming widespread in many areas. One of the most underutilized aspects of the methodology is that the property-prediction maps can help geoscientists understand depositional and postdepositional controls on reservoir development. We illustrate this point via a case study that examines partially dolomitized, restricted to open-marine carbonates of the Ordovician Red River Formation in the Williston Basin. We tied log and seismic data, mapped key reflection events in the 3-D seismic volume, calculated the porosity thickness (thickness × sonic porosity) for the porous zone, and then correlated those data with 21 attributes. We derived a relationship between two attributes (the spectral slope from peak to maximum frequency and the ratio of positive to negative samples) and porosity thickness that yielded a 0.88 correlation coefficient between predicted and actual values. This relationship was used to predict the porosity thickness throughout the 3-D seismic area. The resulting porosity distribution shows (1) good porosity development along the flanks of structures that are associated with visible faulting or steep dips at the underlying Winnipeg level, (2) thin (~17–28 ft [~5–8.5 m]) porous zones throughout much of the field, (3) a large, off-structure porosity zone in an area without well control, and (4) small, irregularly distributed porous zones (most likely the result of noise and/or error in the predictive relationship). In areas where faults and flexures are associated with enhanced porosity development, the slope of spectral frequency attribute may be responding to fractures, with more rapid attenuation of high frequencies occurring in these areas. These observations support a diagenetic model where faults and fractures acted locally as preferential pathways for dolomitizing fluids. Away from these zones, the porosity distribution shows some porosity thickness over the entire area that is consistent to drillstem test data that shows depleted pressures in wells drilled in the early 1990s on otherwise isolated structures.
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Recent advances in seismic acquisition, processing and visualization techniques image carbonate strata with unprecedented resolution. This volume documents the current state of the art in seismic imaging and interpreting of carbonate systems and captures the dynamics of the carbonate system on a large exploration scale and on a small reservoir scale. The book emphasizes the newest approaches in seismic visualization, seismic sedimentology and stratigraphy, seismic attribute analysis and their application for building improved 3-D reservoir models. Among the topics covered are the delineation of the complex histories of carbonate platform sequences from seismic data, the relationships between geometries and forming processes, the imaging of faults for improved mapping of potential fluid migration pathways, and use of seismic attributes for the extraction of rock properties in the sedimentary bodies. The book illustrates the power of integrating seismic and geological data to better predict of the architecture and heterogeneities in carbonate depositional systems. As such the book will be a useful reference for both geologists and geophysicists.