Abstract

The Kugmallit Formation in the Beaufort-Mackenzie Basin is a major progradational wedge of clastic sediments which ranges from Late Eocene to Late Oligocene in age. During the last decade, significant reserves of hydrocarbons have been discovered within the Kugmallit Formation, suggesting that it will eventually become a major petroleum producer.

From the examination of cores, wireline logs and the analysis of biostratigraphic samples, six facies have been defined. These facies were deposited within prodelta (Facies 1), progradational deltas (Facies 2 and 3) and nonmarine delta plain (Facies 4 to 6) environments. The two wells that penetrate the structure (L-19 and L-19A) were correlated by matching the major flooding surfaces which define the top of each shoreline parasequence. Several parasequences at the top of the Kugmallit Formation thin to the north, suggesting that progradation occurred in that direction. Seven additional surfaces were recognized. These surfaces were produced by an apparent basinward shift in facies and could represent local erosion surfaces caused by autocyclic deltaic processes or regionally significant sequence boundaries. Comparison of the preliminary sequence stratigraphic framework established herein with similar studies in the published literature proved to be difficult, owing to differences in scale, depth of investigation and concepts employed.

The sands of the Kugmallit Formation are immature mineralogically and texturally and their composition suggests a provenance that includes sedimentary, igneous and metamorphic terranes. Diagenetic alteration of the unconsolidated sands of the Kugmallit Formation in the Nipterk area is minor; consequently, reservoir quality is largely controlled by depositional parameters such as texture and grain size. The best reservoir quality was observed in coarse grained channel deposits or the clean sands at the top of progradational shorelines.