Hart, Bruce¹, Kamal al Atroshi¹, Justine Sagan¹, Juliana Tebo¹
(1) McGill University, Montreal, QC

ABSTRACT: Seismic Imaging of Diagenesis: A Tool for Studying Hydrothermal Dolomite Systems

Hydrothermal dolomite prospects are often defined seismically, using a combination of qualitative criteria that includes sags on key horizons, fault geometry, changes in amplitude or frequency of the seismic data, and other observations. Drilling results may be “mixed” and little insight is typically gained into the controls on porosity and permeability development. In this presentation we show how integration of seismic and wireline log data may be used to map porosity associated with dolomitization in carbonates. We use both seismic inversion and seismic attribute studies to map (in 2- and 3-D) the distribution of porosity in dolomitized reservoirs of the Appalachian Basin (Trenton-Black River Groups), Williston Basin (Red River Formation) and Jurassic of the Gulf Coast (Smackover Formation). By examining the distribution of porosity we have helped to resolve fundamental questions about the controls on diagenesis in each area. A critical aspect of these studies is the integration of porosity prediction with other types of analyses. Detailed structural and stratigraphic analyses need to be undertaken concurrently using seismic, log and other types of data. Our analyses indicate that hydrothermal dolomitization in the Trenton-Black River Groups is associated with complex basement-involved wrench faulting. Porosity “pods” in the Red River Formation are typically, but not always, associated with underlying structural elements. Porosity in the Smackover Formation is related to both stratigraphic (thrombolitic reefs) and structural elements. Each of these studies provides results that can be used directly in field management, or in the exploration for, or development of, analog fields elsewhere.

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.