BOZEMAN — A team of Montana State University researchers has demonstrated the potential for biofilm and mineral-producing bacteria to stop tiny, hard-to-reach leaks in underground oil and gas wells.
In a recent successful experiment, researchers from MSU's Center for Biofilm Engineering used Sporosarcina pasteurii bacteria to seal microscopic fissures in an Alabama test well's casing, which consists of 9 5/8” metal piping reinforced by cement. Because such fissures can compromise similar wells used to extract hydrocarbons, the field test results suggest widespread industrial application for the technology.
"It was a very successful test," said researcher Al Cunningham, professor emeritus of civil engineering in MSU's College of Engineering. "It was very well received by our industrial collaborator." Collaborators include Schlumberger, the world’s largest oilfield services firm and Montana Emergent Technologies, a Montana-based engineering firm.
The technology uses a process called microbially induced calcite precipitation. In the presence of calcium and urea, a nitrogen-based substance widely used in fertilizers, Sporosarcina pasteurii can rapidly create a deposit of calcite, the hard mineral that constitutes limestone and marble.
In April, the team, led by Adrienne Phillips, MSU assistant professor in the Department of Civil Engineering and principal investigator of the DOE-sponsored project, injected solutions containing Sporosarcina pasteurii into a section of the test well located approximately 1,020 feet underground. By monitoring the pressure of the well, and by using ultrasonic imaging to observe known fissures in the well casing, they confirmed that the calcite produced by the biofilm had sealed the microscopic cracks.
"It's been a wonderful process of taking an initial idea and scaling it up to a technology that seems very relevant to transforming oilfield practices," said researcher Robin Gerlach, professor in the MSU Department of Chemical and Biological Engineering.
In an industrial setting, leaking well casings can result in hydrocarbons, drilling fluids and other substances being released into adjacent rock strata and groundwater. Leaked gases, including methane, the main component of natural gas, can migrate to the surface and become airborne. Methane is a powerful greenhouse gas that contributes to climate change, so methods to contain it are increasingly sought after, Phillips said.
"It's exciting to work on a problem that people care about," Phillips said. "We're addressing an environmental problem of international concern."
The technology could also benefit efforts to capture and store, or sequester, climate-altering carbon dioxide, a process that requires airtight wells for transferring the pressurized gas to underground reservoirs.
Industry experts like Schlumberger are able to stop many well leaks, mainly by using cement. But sealing small fissures is difficult because of cement's high viscosity.
"When we talk to oilfield service providers who do this kind of work, they claim the success rate for this kind of leak is between one and 10 percent," said Lee Spangler, who directs the research project as well as MSU's Energy Research Institute. "The MSU team was able to seal this leak in their first attempt. I think that's of huge consequence.”
The research team is now investigating ways to make the technology more widely applicable. By cultivating similar biofilm-producing bacteria that can withstand the high temperatures found deep underground, the researchers hope to produce a tool for plugging even the most hard-to-reach leaks.
For that effort, the researchers have received funding through the Montana Research and Economic Development Initiative, a $15 million statewide research program enacted by the 2015 Montana Legislature to solve Montana problems and spur economic growth.
"We're very appreciative of that support," said Gerlach. "It has allowed us to venture into areas that would be difficult to venture into otherwise.”
Gerlach thinks it will pay off.
"We see immense application (for this technology)," he said.
Contact: Adrienne Phillips, (406) 994-2119 or firstname.lastname@example.org; or Robin Gerlach, (406) 994-1840 or email@example.com