Hydrocarbon Migration in Mackenzie Delta Sediments

Lloyd R. Snowdon

Macroscopic-scale hydrocarbon migration in Tertiary rocks of the Beaufort-Mackenzie basin has been investigated using three analytical approaches: (1) spatial constraints imposed by the physical distribution of oil source rock pairs defined by detailed chemical correlation, (2) determination of vertical migration by comparison of the level of thermal maturation of a crude oil with that of the host reservoir rocks, and (3) observation of the relative concentration of biomarker compounds that may be sensitive to the extent of migration. In the offshore of the Mackenzie delta, vertical migration is not evident, but no available data indicate the extent or importance of lateral migration. The stratigraphic and structural position of the source rock relative to the reservoirs ndicate that faults played a major and necessary role in the migration process. The level of thermal maturity of most Tertiary oils in this basin is too low to permit the application of the published direct-migration indicator.

Chemical properties of the oils indicate that two or more episodes of generation and migration have occurred and that extensive invasion by meteoric water has occurred at various times in this basin. The observed offshore decrease in the gas to oil ratio has not been explained but may be related to migration.

AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.