The economics look sound, judging from a 2009 study by Harvard’s Belfer Center for Science and International Affairs. The study found that using enhanced oil recovery revenues could cover the entire price premium for carbon capture on coal-fired power, assuming oil fetches about $75 a barrel. Oil was selling above $74 on Friday.
Research also shows that oil-field operators can keep the carbon dioxide from escaping to the atmosphere. Carbon dioxide that returns to the surface when the oil is produced is readily separated from the oil and reinjected underground. A decade of monitoring has found no net losses of postindustrial carbon dioxide injected into oil fields near Weyburn, Saskatchewan.
The University of Texas is confirming those findings at the world’s oldest and largest EOR operation: an oil field about a two-hour drive northeast of Penwell. Since 1972, a succession of owners have injected over 150 million tons of carbon dioxide into the oil-soaked fossilized reef, which lies 6,000 to 7,000 feet below Snyder, TX. The field is pierced by over 2,000 wells, but, according to Susan Hovorka, a senior geologist with the university’s Gulf Coast Carbon Center in Austin, TX, three years of searching has yet to reveal a trace of leakage.
Hovorka points, for example, to aquifers that begin just 300 feet above the carbon dioxide, which is injected at 2,200 pounds per square inch. The water shows neither the elevated acidity or pressure that a leak should induce. “The wells are sealing better than we’d anticipated. It’s cheering,” says Hovorka.
Whether such sequestration represents a net carbon reduction remains, however, a matter of interpretation, since the oil produced will eventually be burned as fuel. A life cycle assessment from Carnegie Mellon University last fall estimated that, when fuel combustion is factored in, such enhanced oil operations release 3.7 to 4.7 tons of CO2 for every ton of CO2 sequestered. EOR operations would have to use three times as much CO2 per barrel of oil produced to completely offset their tailpipe emissions.
Hovorka expects just that to happen if and when carbon pricing becomes a reality. She says that under current conditions, EOR operators maximize the oil-to-CO2 ratio to minimize costs, but can adjust operations to flip the ratio if carbon pricing means there’s value in offsetting emissions. “The carbon balance of EOR is market driven, not implicit in the technology,” says Hovorka.
Miller says it is unfair to pin the downstream emissions on Summit, since the resulting oil is likely to displace other, less desirable oil production. “It’s not realistic [to think] that we’re not going to pull oil out of the ground. I’d rather go into existing wells rather than offshore and into environmentally sensitive places to dig for oil,” she says.