by Peter McKenzie-Brown
Once an obscure part of waste management, the injection underground of unwanted gases will soon become a huge part of Western Canada’s business. The industry has had plenty of practice at disposing of nastier materials than carbon dioxide.
Oil and gas operations produce two kinds of acid gases – hydrogen sulfide (H2S) and carbon dioxide (CO2). The former is usually stripped from the gas stream and converted into sulfur. Tom Byrnes, a reservoir engineering manager at the Energy Resources Conservation Board, says the sulfurous impurity is sometimes just stripped from the gas and re-injected underground. “It’s usually an economic question. There may be small volumes of H2S in the gas stream, or the infrastructure [to strip out sulfur] may not be in place to make it practical.” In Alberta, the board regulates all disposals through disposal wells and first approved an H2S re-injection project in 1989.
Both of these acid gases are routinely stripped from natural gas for re-injection, as appropriate. “But the smaller the concentration of H2S or CO2 there is in the gas stream, the more expensive it is to get it out. It’s a problem of diminishing returns,” Byrnes says.
If H2S can have commercial value as a source of sulfur, CO2 is frequently injected into operating oilfields to stimulate production. This is not new. Carbon dioxide has long been used for enhanced oil recovery, to urge additional barrels out of elderly oilfields. One such project has been operating in the 50-year-old Weyburn oilfield in southern Saskatchewan for nine years.
Balance of story at languageinstinct.blogspot.com/2009/06/pr...
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