Research by US university shows bacteria could plug oil and gas leaks
22 August 2016
Montana State University researchers have shown that biofilm- and mineral-producing bacteria can stop tiny, hard-to-reach leaks in underground oil and gas wells. In a recent experiment, researchers from MSU’s Center for Biofilm Engineering used bacteria to seal microscopic fissures in a test well’s casing, which consisted of metal pipe reinforced by cement.
Such fissures can compromise similar wells that are used to extract hydrocarbons, so the test results suggest the technology could be used widely in the industry.
According to a press release from the MSU News Service, Al Cunningham, professor emeritus of civil engineering at MSU, said “It was a very successful test.” Cunningham is a principal investigator on the project alongside Adrienne Phillips, assistant professor of environmental engineering, Robin Gerlach, professor of chemical and biological engineering, and Lee Spangler, associate vice president of research at MSU.
The researchers collaborated with oilfield services company Schlumberger 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 fertilisers — the bacterium Sporosarcina pasteurii can rapidly create a deposit of calcite, the hard mineral that constitutes limestone and marble.
In April, the team, led by Phillips, injected solutions containing bacteria into a section of a test well 1,020 feet beneath Alabama. By monitoring the pressure of the well and 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 Gerlach.
Leaking well casings can let hydrocarbons, drilling fluids and other substances out into adjacent rocks 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 pressurised gas to underground reservoirs.
Companies such as Schlumberger can stop many well leaks, mainly with cement, but sealing small fissures is harder because of cement’s high viscosity.