Training a New Generation
The Gulf Coast Carbon Center (GCCC) was co-founded in 2002 by three scientists at the Bureau of Economic Geology: current director Scott Tinker, senior research scientist Sue Hovorka, and former associate director Jay Raney. One of the missions of GCCC is to “educate the next generation of carbon management professionals and regulators.”
“If carbon sequestration were to become commercial, we'd need more practitioners in the U.S.,” says Sue Hovorka, lead scientist at GCCC. She says energy companies, oil-field service companies, and electric utilities are increasingly looking for skilled carbon management professionals, but there are few places for workers to get training.
In the past year, GCCC has grown tremendously with the hiring of two research associates, three postdoctoral researchers, three visiting scholars, and eight graduate students. Reflecting the multidisciplinary nature of this new field, the researchers approach carbon sequestration from many different directions, including monitoring, modeling, environmental risks, economics, public policy, and regulation.
The new researchers hail from many parts of the world, including China, Korea, Iran, Ghana, India, and Venezuela, as well as different areas of the U.S.
“The problem of greenhouse gas emissions is international, and so the solution has to be too,” says Sue Hovorka. “So if we don't have people from many different backgrounds, we probably don't have a shot at a solution that will work globally.”
Jiemin Lu is a postdoctoral researcher from China, who joined GCCC this past year. He received a Ph.D. at the University of Edinburgh for his study of a North Sea oil field having a high concentration of CO2 that served as a natural analog to engineered carbon storage projects. He says that the prospect of working on real carbon storage projects attracted him to Texas to work at GCCC.
“This program is first class,” says Lu. “The injection project at Cranfield is big. We're aiming to inject 1 million metric tons of CO2 a year. There aren't many projects of this size in the world. Unlike my Ph.D. work with an analog, this is the real business, so we can learn a lot more in terms of injection and monitoring.”
Its high-profile research projects and ability to attract top young talent from around the world attests to the strength of GCCC's research. Still, most of the education at GCCC occurs as on-the-job training. Hovorka and Lu both say that if the Jackson School of Geosciences, which subsumes the Bureau and GCCC, offered a Master's program or even formal courses in carbon sequestration, GCCC would be better positioned as a leader in this potentially big new field.
The expertise of 15 organizations is tapped to conduct this experiment: site characterization, modeling, hydrology, and geochemistry (Bureau of Economic Geology); site host and CO2 expert (Denbury Resources); smart well engineering (Sandia Technologies); cutting-edge monitoring tools (Lawrence Berkeley National Laboratory); crosswell electrical imaging (Lawrence Livermore National Laboratory); geochemical analysis (U.S. Geological Survey, Mississippi State University, Oak Ridge National Laboratory); wireline logging (Schlumberger Carbon Services); modeling (QEA and Advanced Resources International); hydrology and near-surface sampling (University of Mississippi and U.S. Environmental Protection Agency); and geomechanical response (Pinnacle Technologies).
To answer the first question—about fluid containment in an area with many old wells—the research team designed a dedicated observation well. The well is perforated at 10,300 feet (in the lower Tuscaloosa injection zone and future production zone), as well as in the monitoring sandstone 400 feet higher. Temperature and pressure meters were placed at these perforations, isolated from one another by an impermeable packing material, and connected via cable to a satellite uplink. Pressure and temperature in both zones are recorded every minute and transmitted to an Internet system every 10 minutes, allowing team members to track the progress in near real time. Last July, Denbury began CO2 injection into the lower Tuscaloosa Formation in nearby wells.
“During the injection, CO2 and brine fluids flow through the injection horizon, and we want to demonstrate that it isn't impacting the geology or groundwater above,” says Tip Meckel, research associate at the Center. “That would prove geologic containment of injected CO2.”
Pressure in the lower Tuscaloosa Formation responds quickly to changes in injection. According to models of the subsurface, it might be several more months before the CO2 plume reaches the observation well. Over the past 6 months, pressure has increased more than 1,000 psi in the injection zone, but there has been no corresponding change in pressure in the monitoring sandstone 400 feet above, suggesting no “pressure communication” between the two zones. Researchers are waiting for indicators that CO2 has reached the observation well, an event known as breakthrough. Models suggest that it may take several more months. However, early indications are that the CO2 remains contained and injection pressure remains stable, even in an area with many old wells.
As this observation continues, the next larger phase injection is under way. Four new wells, located outside and deeper than the oil-producing area, will be used for CO2 injection. The injection rate will be increased to a million metric tons per year to simulate the output of a typical coal-fired power plant more closely. Two dedicated observation wells have been designed with a novel suite of instruments, which, combined with an array of far-field measurements, will allow the team to gain a more quantitative picture of high-volume injection.
Of particular interest is linking the magnitude of pressure change in front of the CO2 plume to the geometry of the plume and the rate of injection. The team will measure how CO2 distribution in the rock changes with time and how rapidly fluids move within the plume. A series of measurements will be used to determine how the rock is stressed and deformed in response to changes in pressure. Rock stress will help researchers determine safe injection pressures that will not create ruptures or otherwise cause geologic seals to leak.
Bridge to the Future
Many advocates of the practice see CCS not so much as a magic bullet, but more as a bridge to our energy future—a way to make current energy sources cleaner while scientists and engineers are developing something better.
“Carbon capture and storage allows current and near-term energy needs to be met using traditional sources until alternative sources are economic at the scales needed for long-term demand,” says Meckel.
“I think the major point to be made is that if a geological sequestration site is properly characterized and chosen, there should be very little chance of impact at the surface,” says Hovorka. “The technology exists through all the tools developed by the oil and gas industry to characterize the subsurface. So it's not a hard thing to do.