This piece is about Excelsior's Energy Limited experimental situ combustion bitumen-recovery process called, "Combustion Overhead Gravity Drainage."
Excelsior has developed the COGD process in cooperation with Hot-Tec Energy Inc., a private company affiliated with members of the In-situ Combustion Research Group from the Department of Chemical and Petroleum Engineering at the Schulich School of Engineering, University of Calgary. The In-situ Combustion Research Group is a global leader in the application of in situ combustion recovery processes.
The company said it expects that the application of the COGD recovery process could result in significantly improved bitumen economics through both enhanced recovery gains and substantial reductions in the amount of required water, fuel gas and diluent.
As a result, the company will be focussing its resources towards an experimental in situ COGD pilot project. A project application will be submitted in the second quarter of 2009 with anticipated regulatory approval in approximately one year for the subsequent implementation and commissioning of the pilot in the first quarter of 2011.
The COGD process is expected to bring a significant reduction in water usage for steam generation by up to 80% compared to a similar sized SAGD process. It is expected to yield a significant reduction in fuel gas consumption for steam generation by up to 80% compared to a similar sized SAGD process, as COGD uses the in situ energy of the bitumen which would otherwise be unrecoverable.
It also involves a reduction in diluent demand as a result of potential in situ bitumen upgrading and a reduced environmental impact through decreased water draw and water recycling, decreased fuel gas and diluent demand.
All of these should significantly improve project economics as COGD recoveries are estimated to be as much as 50% greater than SAGD recoveries, and capital and operating costs are estimated to be considerably lower than comparable SAGD projects.
COGD employs an array of vertical air injector ignition wells above a horizontal production well located at the base of the bitumen pay zone. A short initial period of steaming prepares the cold bitumen for ignition and develops enhanced bitumen mobility in the reservoir. Upon ignition a combustion chamber develops above and along the length of the horizontal well with combustion gases segregated in the upper part of the reservoir and hot bitumen flowing by gravity into the horizontal production well.