Petrophysical Properties of Grosmont Bitumen, Alberta, Canada

Yi Zhao
Department of Earth and Atmospheric Sciences, University of Alberta Edmonton, Alberta, Canada; [email protected]

Natural bitumen is generally defined as hydrocarbon with viscosity greater than 10,000 centipoises measured at reservoir condition. On a global scale, the estimated volume of technically recoverable natural bitumen is 651 billion barrels, of which 81% is found in Alberta, Canada. Beneath the giant Cretaceous oil sand deposits in Alberta, the Devonian Nisku, Upper Ireton and Grosmont Formations together host nearly 500 billion-barrel initial oil in place, with Grosmont Formation being the single largest bitumen carbonate reservoir in the world.

Due to severe biodegradation, the bitumen in Grosmont is characterized by extremely high viscosities (more than a million centipoises on average), very low gravity, and complex distribution. In order to map out the vertical and lateral variation of bitumen properties, samples from 15 wells along a northwest-southeast cross section in the study area were selected for bitumen properties analysis, including viscosity measurement, asphaltene content test, elemental analysis, thermal gravimetric analysis and simulated distillation test. With the assistance of Gas Chromatography-Mass Spectrometry, aging effect on bitumen will be established by comparing the alterations of fluid properties and biodegradation levels between fresh samples and old ones. A correlation will then be introduced to correct old bitumen properties into fresh ones`, which are the closest estimation of their in-situ state.

The results from this investigation will contribute a necessary description of natural bitumen in Grosmont, which benefits future exploration & production.

AAPG Search and Discovery Article #90083 © 2008 AAPG Foundation Grants in Aid