Sagan, Justine¹, Bruce Hart¹ 
(1) McGill University, Montreal, QC

ABSTRACT: Seismic and Structural Analysis of a Hydrothermally Dolomitized Trenton-Black

Trenton-Black River reservoirs in the Appalachian Basin are typically associated with fault related hydrothermal dolomitization, but the details of how faulting and fluid flow have interacted remain poorly documented. Integration of 3-D seismic, wireline and production data from Saybrook Field in northeastern Ohio has shown that the productive trend there is controlled by a 5 km long, NW-SE oriented basement fault that was probably reactivated during the Taconic Orogeny in the Mid- to Late Ordovician. The far-field stresses of this compressional activity resulted in strike-slip movement of the pre-existing fault to create a complex positive flower structure that branches upward at least 1350’ into the Trenton-Black River interval. Relatively small (<15 acre) collapse structures between splays of the flower structure are the primary drilling targets. Faults were mapped using amplitude and coherency versions of the seismic data. Curvature analysis of horizons mapped in the seismic data allowed us to further constrain the location and orientation of subtle structures. Fault morphology provides insights into the path of the dolomitizing fluids, whereas the distribution of porosity, and thus the location of the reservoir, has been mapped in 3-D using a seismic attribute study. We integrated wireline log-based measurements of porosity with seismic attributes to predict the distribution of porosity throughout the 3-D volume. Advanced visualization technologies allowed us to integrate faults and porosity predictions, thereby gaining fundamental insights into the relationships between faulting, fluid flow and reservoir development. Our results, and the methodology that we employ, have application in analog settings elsewhere.

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