Bacteria and Bitumen
Like all crude
oil, Canada's bitumen and heavy oil resources started as living material.
Hundreds of millions of years ago, the remains of tiny plants and animalsmainly algaewere buried in sea beds. As the organic materials became more
deeply buried, they slowly "cooked" at temperatures between 50 and 150
degrees Celsius. Eventually, this process converted the materials into liquid hydrocarbons (compounds of hydrogen and carbon), as well as sulphur compounds, carbon dioxide and water.
then migrated up through sedimentary rocks until they reached the surface or
something blocked their progress. Conventional light crude oil is usually
trapped in porous rocks under a layer of impermeable (non-porous) rock. In such reservoirs, the oil is not in an underground "lake" but rather held in
the pores and fractures of rock like water in a sponge.
Oil sands are
different. Fifty million years ago, huge volumes of oil migrated eastward and
upward through more than 100 kilometres of rock until they reached and saturated
large areas of sandstone at or near the surface. Bacteria then feasted on the
hydrocarbons and slowly turned the oil into bitumen. While the Athabasca oil sands are the world's largest known hydrocarbon resource, geologists point out that the volume of original crude digested by the
micro-organisms was at least two or three times greater than what now remains as
eat the simplest hydrocarbons first and convert them into carbon dioxide and
water, while ignoring the big hydrocarbon molecules like asphalt and the
non-hydrocarbons, such as sulphur and nickel. As a result, there are more heavy
hydrocarbons, sulphur compounds, and metals in bitumen than in conventional
crude oil. This makes processing more difficult and expensive.
The challenge of
the future lies in continuing to develop these oil sands and heavy oil resources
to meet the fuel needs of North America in a way that is economical and
sensitive to the needs of regional residents and the quality of the natural
Petroleum Communication Foundation. Canada's Oil Sands and Heavy Oil. Calgary: Petroleum Communication Foundation, 2000. With permission from the Centre for Energy