Boundary Dam proponents have been saying that 1 million tonnes annually of carbon dioxide will be permanently sequestered in the Weyburn Oil Field. However according to data from the  ICO2N - an industry association representing companies that wish to develop Carbon Capture and Sequestration across Canada - that figure is not correct. A more accurate number would be 700,000 tonnes annually.

When carbon dioxide is injected into the Weyburn Oil field, it combines with the crude oil that is in the field. The resultant carbon dioxide/crude oil mix is less sticky than the crude oil alone, as a result it flows to the various oil wells, is pumped to the surface and recovered. 

 
Source: California CCS Coalition

Source: California CCS Coalition

 

When the crude oil/carbon dioxide mix reaches the surface; an attempt is made to separate the two: recovered carbon dioxide is re-injected into the Weyburn field and crude oil is sold. However this separation process is not perfect and a certain amount of carbon dioxide is lost to the atmosphere during processing. 

According to a study (see page 8) undertaken for the ICO2N network, approximately 30 percent of every tonne of injected carbon dioxide is lost to the atmosphere during processing. 

 
Source: Net Greenhouse Gas Impact of Storing CO2 Through Enhanced Oil Recovery. ICO2N January 2013

Source: Net Greenhouse Gas Impact of Storing CO2 Through Enhanced Oil Recovery. ICO2N January 2013

 

In other words and for every tonne (1,000 kilograms) of carbon dioxide which is injected into the Weyburn Oil Field, approximately 300 kilograms are lost to the atmosphere. So rather than 1 million tonnes being permanently sequestered each year - a more realistic number is 700,000 tonnes.