Challenges in the Production of Heavy Oil

The deposits of tar-like bitumen found in central and northern Alberta are among the world‘s largest petroleum resources (see Quick Facts Fig 3) However, the viscous substance is too thick to flow through rocks, well bores and pipelines. Many technological and economic challenges have to be overcome in order to produce and transport bitumen and to process it into desirable products such as gasoline and diesel fuel.

Mineable bitumen deposits are located near the surface and can be recovered by open-pit mining techniques. New methods introduced in the 1990s considerably improved the efficiency and reduced cost. This led to multibillion-dollar expansions of the existing projects plus proposals for additional mining projects. The new systems use hydraulic and electrically powered shovels to scoop up the oil sand and load it into enormous trucks which can carry up to 320 tonnes at a time. In the plant, a hot water process completes the separation of the bitumen from sand, water and minerals.

Figure 4 - Open Pit deposit

In-situ production methods are used on bitumen deposits buried too deep for mining to be economical. These techniques include steam injection, solvent injection and firefloods in which oxygen is injected and part of the resource burned to provide heat. So far steam injection has been the favored method. In heavy oil and in-situ bitumen production, enhanced recovery generally involves the application of heat, most commonly by steam injection. Major improvements in heavy oil and bitumen recovery have been achieved by steam-assisted gravity drainage (SAGD) which uses parallel pairs of horizontal wells for (Fig. 5) steam injection (white arrows) and oil recovery(red arrows).

Figure 5 – SAGD In-Situ Production