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Cutting emissions in natural gas processing

March 5, 2010

Keyera Energy has reduced greenhouse gas emissions by up to 19 per cent at five of its facilities in western Canada by using an acid gas injection process. The acid gas process not only reduces the company's CO2 emissions and cuts sulphur emissions, the system also has the potential to help sequester carbon dioxide deep underground in geological formations.

In the processing of natural gas, hydrogen sulphide (H2S) and carbon dioxide (CO2) are removed from the gas for a variety of safety and mechanical reasons. The process is called "sweetening" because once the impurities are removed; the resulting "sweet" gas is ready for further processing.  An amine solution - which reacts with the acid gas molecules - draws the components of the sour gas away from the raw gas stream, creating an acid gas.   

At Keyera's facilities, the acid gas is moved through a pipeline to an injection well where it is injected into a deep underground reservoir. The sulphur compounds and CO2 are not released to the atmosphere; they're permanently stored in the deep geological formation. 

Whenever possible, Keyera used existing pipe and pipeline corridors to move the acid gas and to help reduce the impact on the environment.  The pipelines are equipped with specialized corrosion detection devices for on-line monitoring and a metering system for leak detection.

It took plenty of research to find suitable depleted oil and gas reservoirs that could accommodate the acid gas that Keyera's facilities will produce over the coming decades. A reservoir becomes available as a result of the removal of oil and/or gas. This creates the ideal setting for the acid gas since this is essentially where the acid gas was originally located.  After extensive geological studies, the company identified a number of reservoirs located more than one mile below the surface that would be suitable.

Our Brazeau River gas plant acid gas injection system provides a good example of successful sulphur recoveries.  As soon as the system started running, sulphur recoveries improved from 92.1 per cent to a minimum of 98.4 per cent.  Once Keyera achieved full injection, 100 per cent of the sulphur was recovered. In aggregate, Keyera has reduced its sulphur emissions by 32 per cent since adopting acid gas injection at five of its facilities.

Over the past decade, Keyera has reduced its emissions while processing more gas -- and doing it better.