Friday, 17 June 2011

Tar Sands 1

2 Update
I've been resisting the temptation to do an article on Tar Sands as it is so widely covered by environmental media and NGO outlets. But when you're constantly bombarded with images and footage of the wanton destruction taking place in Northern Alberta in Canada, you can't stop words such as outrage, insanity and sheer stupidity from popping into your head. It also makes you feel inclined to pose the question; would any reasonable normal person stand back and allow this to happen? The following video offers a possible perspective:

A brief history
It wasn't until 1967 that Commercial exploitation of tar sands became feasible. Since then production has fluctuated with world oil prices. More recently with the rise of prices due to increased demand from developing economies like China, coupled with unrest in the Middle East, production has soared. Current rates of production are estimated at 1.3 million barrels per day, rising to around 3 million by the end of the decade. Looking further ahead, output could rise to 5 million.

For a 'beginners guide' to tar sands - or the more 'politically correct' oil sands, the 'cleaner' description branded by the Alberta Government - visit the Alberta Government's website. 

Geological background
National Geographic Magazine describes the geological process that formed the oil sands in an article from March 2009, The Canadian Oil Boom - Scraping Bottom. Initially the oil deposits were similar to the light crude already present in Canada. But 'Tens of millions of years ago, geologists think, a large volume of that oil was pushed north-eastward, perhaps by the rise of the Rocky Mountains. In the process it also migrated upward, along sloping layers of sediment, until eventually it reached depths shallow and cool enough for bacteria to thrive. Those bacteria degraded the oil to bitumen'. As a result of millions of years of bacterial degradation, the bitumen is carbon rich and hydrogen poor. So upgrading is required (see below).

Processing
There are two main methods of extraction. The first uses strip mining. Huge hydraulic and electrically powered shovels dig up the tar sands and load them into enormous trucks that can carry up to 320 tons of tar sands per load.
The second method of extraction is In situ. Steam Assisted Gravity Drainage (SAGD) is the predominant process. This involves drilling two wells and pumping heated steam down one well to soften the bitumen down into liquid form. It is then forced up the second well, allowing a more conventional form of recovery.

In situ is used to recover deposits that are deeper underground and can't be recovered by mining. The SAGD process is illustrated here: