Crude oil and natural gas have been the building blocks for Alberta’s economy for the past 60 years and are sure to remain the economic cornerstone for decades to come.

But while conventional petroleum resources dominated the 20th century, the 21st century will see the rise of unconventional oil and gas driven by the innovation needed to develop these resources.

Oil and gas: what they are and where they come from

Crude oil and natural gas are fossil fuels made up of hydrogen and carbon, or hydrocarbons.

Most scientists agree that hydrocarbons began to form millions of years ago when marine animals and plant life were buried under mud, silt, and other sediments in ancient oceans. As time went on, more sediment continued to accumulate over the top, which in turn increased subsurface heat and pressure.

This heat and pressure subsequently “cooked” the organic remains, slowly converting them into hydrocarbons:

·         Bitumen (found in large quantities in northern Alberta) is located closer to the Earth’s surface and has been subjected to lower temperatures and less pressure.

·         Conventional oil (lighter than bitumen) is generally trapped deeper and has cooked for longer at higher temperatures of around 65^oC.

·         Natural gas was created as the organic material was subjected to even greater pressures and higher temperatures in excess of 148^oC.

Constant formation pressure forced the hydrocarbons to migrate from their source rocks to form “pools” in porous sedimentary rocks, such as sandstone, where they were trapped by impermeable cap rocks, faults, and other geological features.

Natural gas, which is far lighter than crude oil, can rise above an oil deposit and also act as a trap. Gas is sometimes trapped within the oil itself and released only when the pressure on the oil is lowered during production operations.

Unconventional hydrocarbons, such as bitumen found in northern Alberta oil sands and coalbed methane (CBM), are generating a lot of excitement within Alberta’s energy sector due to their huge potential.

Western Canada Sedimentary Basin

Spanning four provinces and parts of two territories, and covering more than 1.5 million square kilometres, the Western Canada Sedimentary Basin (WCSB) is the country’s most important oil- and gas-bearing region. Alberta is located in heart of the basin, boasting the greatest share of the oil and gas resources.

Vast hydrocarbon resources are found in the WCSB for a number of reasons, including the presence of:

·         Good source rocks (organic rich shales),

·         Suitable reservoir rock (porous sedimentary rock with good permeability), and

·         Impermeable beds to form cap rocks.

Geologists believe the basin formed as a result of tectonic activity that both shifted the North American continent westward and, after colliding with the micro-continents that now form British Columbia, caused the crust to warp downwards, creating the space needed to deposit the sediments.

In addition to the WCSB’s westward thrust, there has also been a slow northward advance. Alberta was in a tropical environment at the time the sediments were being deposited, and life abounded in the ocean and seas that covered the ancient sedimentary basin.

The early shales, later shales, and coals that formed during this period were rich in the organic material that would eventually be transformed into hydrocarbons. Tectonic activity caused much of the organic material to be buried at depths suitable for the forming of oil and gas.