Research will improve techniques for monitoring injection of CO2 underground

Researchers are testing new geo-electric techniques that could complement seismic tools in monitoring the injection of carbon dioxide (CO2) into reservoirs deep underground.

The current mainstream monitoring techniques measure seismic waves that travel underground because these waves are affected by the injection of CO₂ and these changes are used to track where the CO₂ is going says the project's lead investigator, Dr. Bernard Giroux, of Institut national de la recherche scientifique (INRS).

Carbon Management Canada (CMC), a federal Network of Centres of Excellence that supports game-changing research to reduce CO₂ emissions in the fossil energy industry as well as from other large stationary emitters, is providing Giroux and his team $450,000 over three years. In its 2012 round of funding, CMC is awarding $3.75 million to Canadian researchers working on eight different projects. The awards were made after a rigorous, international, peer-reviewed process.

"The rock contains water or oil or gas and we are replacing that with CO₂, which has different physical properties. The injection process also changes the pressure and that can have a strong influence on the overall properties of the rock. Thus, seismic properties are both affected by changes in fluid and pressure," says Giroux.

"So, when we're injecting CO₂ we're changing both fluid and pressure, and there's an ambiguity here. We're monitoring something, but we're not exactly sure in which proportion we should attribute measurements to changes in pressure or changes in fluid."

Giroux is leading an international team of researchers from the University of Alberta, the Geological Survey of Canada, the Technische Universität Bergakadmie Freiberg and the GFZ Centre for CO₂ Storage, Potsdam. Also contributing to the project are Natural Resources Canada, the Petroleum Technology Resource Centre, and Junex.

There are three components to the research that will improve monitoring of injecting CO₂.

In the lab, the researchers will fill in gaps of knowledge about the electrical properties of CO₂ as well as cross relationships between seismic and electric properties. "We want to understand the relationship between fluid nature, pressure changes and temperature changes to improve our fundamental understanding of how CO₂ affects the electrical properties of the rocks," says Giroux.

Using a saline aquifer in Saskatchewan and a reservoir in Quebec, the researchers will test different methods of measuring electrical properties underground. More specifically, the team will test how measuring the magnetic field instead of the electric field (as done usually) can be used to infer the electric conductivity of the rock.

The project will also develop numerical models that will help assess all the data gathered.

"We want, as much as physically possible, to give guarantees that we know where every drop of CO₂ is going," says Giroux, "and we want to increase the safety and public acceptance of these sequestering operations."

Provided by Carbon Management Canada