Applications of 1-D Basin Modeling to Hydrocarbon Generation and Reservoir Filling History in Trutch Map Area and Adjacent Plains, Northeastern British Columbia and Northwestern Alberta

Ayse Ibrahimbas and Cindy Riediger
University of Calgary, Calgary, AB

Quantitative 1-D basin modelling is applied to the Paleozoic to Mesozoic stratigraphic section in 11 wells in the area bounded by 57°-58°N and 118°-124°W. The study constructs the thermal and burial history of this area in order to investigate the timing of hydrocarbon generation from known source rocks, migration fairways and timing of migration into Triassic traps. Known source rocks include Exshaw, Montney, Phosphate Zone, Pardonet, Nordegg and Wilrich formations.

The amount of the Tertiary erosion increases dramatically from 300 to 2200 metres from east to west, with concomitant increase in thermal maturity towards the west. The Exshaw Formation enters the oil window 243 Ma in the west with expulsion starting as early as 113 Ma, and in the east the hydrocarbon generation starts 81 Ma but doesn't reach the threshold of expulsion. The Mesozoic source rocks are in the oil window west of 120°W, with hydrocarbon generation starting about 88-62 Ma.

Quantitative basin models are also used to infer temperature histories of known reservoir units, which in turn may be used to assess risk of thermochemical sulphate reduction (TSR) in deep carbonate reservoirs, and to assess biodegradation risk in shallower reservoirs. For example, all Elk Point reservoirs exceed the minimum paleotemperature of 80°C needed for paleopasteurization, consistent with the lack of biodegradation in the oils in these reservoirs. However, some stratigraphically younger reservoirs in the eastern part of the study area have never reached 80°C, suggesting an increased risk of biodegraded (lower quality) oils.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005