Wierzbicki, Richard A.1, Nancy J. Harland1
(1) EnCana, Calgary, AB
ABSTRACT: Diagenetic Model: Deep Panuke Reservoir, Nova Scotia, Canada
The Jurassic aged Abenaki carbonate complex was deposited along the eastern margin of the North American continental shelf. The Deep Panuke reservoir was discovered in 1998 with the drilling of the PanCanadian PP-3C well. The PP-3C well encountered a thick vuggy limestone reservoir, subsequent wells encountered both vuggy limestone and dolomite.
Early work by Eliuk suggested that reservoir development on the carbonate margin was related to lowstand development of a meteoric lens, leaching of allochems, and mixing zone dolomitisation.
The services of Dr. Jeff Dravis and Dr. Ihsan Al-Aasm were retained to conduct a petrographic, isotopic, and fluid inclusion study of the reservoir.
The reservoir has been subjected to multiple phases of dissolution, calcite cementation, fracturing, and dolomitisation. Almost all of the diagenesis is post burial. Shortly after deposition calcite cementation occludes much of the primary porosity. Aragonite and high Mg calcite fossils were dissolved and infilled with blocky calcite. Subsequently matrix dolomitisation developed along the platform margin. Later, saddle dolomitisation occurred, lining vugs and fractures and recrystallising some of the earlier dolomite. Dissolution of dolomites and limestone created vuggy limestone porosity. Fractures are an important component of the permeability network of the reservoir. Fractures consist of micro-fractures and swarms of short length macrofractures, some of which have been enhanced by leaching. Reservoir distribution appears to be controlled by fault and fracture networks creating conduits for diagenetic fluids.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.