ABSTRACT: Correlation of Foraminiferal Coloration (FCI) and Time-Temperature (TTI) Indices from Beaufort Sea Exploration Data

MCNEIL, D. H., and D. R. ISSLER, Institute of Sedimentary and Petroleum Geology, Geological Survey of Canada, Calgary, Alberta, Canada

A new technique for determining thermal maturity has been developed using color alteration of the mucopolysaccharide cement that binds and surrounds every individual grain in the wall of agglutinated foraminifers. This new scheme is referred to as the Foraminiferal Coloration Index (FCI), with values ranging from 0, representing Recent unaltered specimens, to 10, representing highly altered, black opaque specimens (equivalent to vitrinite reflectance values of 3.0 to 4.0%).

Agglutinated foraminifers are abundant in deltaic deposits of the petroleum-bearing Oligocene Kugmallit sequence in the Beaufort Sea of Arctic Canada. The Amauligak J-44 discovery well penetrates these strata to a depth of 4002 m where the bottom hole temperature is approximately 110 degrees C. The temperature history of Amauligak J-44 and other nearby wells was simulated using a thermal model constrained by geological and geochemical data. Calculated time-temperature index values are correlated with FCI values that range from 1.5 to 7.5. Graphs of FCI values versus time indicate the potential variation of FCI values for sedimentary sequences that have been subjected to constant heating rates.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)