Datapages, Inc.Print this page

Robin A. Pearson1, Bruce S. Hart2
(1) New Mexico Institute of Mining and Technology, Socorro, NM
(2) New Mexico Bureau of Mines and Mineral Resources, Socorro, NM

Abstract: 3-D seismic attributes help define controls on reservoir development: case study from the Red River Formation, Williston Basin

The use of 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 to understand depositional and post-depositional 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 then mapped key reflection events in the 3-D seismic volume. We then measured the gross thickness of the porosity zone from sonic logs and correlated those data with 24 attributes. We derived a relationship between two attributes, spectral slope from peak to maximum frequency and ratio of positive to negative samples, and porosity zone thickness that yielded a 0.83 correlation coefficient between predicted and actual values. We then used this relationship to predict porosity throughout the 3-D seismic area. Good porosity development is localized along the flanks of structures. These areas are associated with visible faulting or steep dips at the underlying Winnipeg level, and the spectral slope attribute may be responding to fractures. All of these observations support diagenetic models whereby movement of dolomitizing fluids was strongly influenced by fractures. Although thick porosity zones are localized features, some relatively thin (6 - 10 m) porosity is predicted throughout much of the field. This is consistent with DST data that show depleted pressures in wells drilled in the early 1990s on otherwise isolated structures.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana