Microbes may prolong Marcellus shale production, NETL research finds

March 6, 2017
The prolific Marcellus shale may be a rich source for microbial life, which could help refill the important domestic natural gas reservoir by producing methane, scientists at one of the US Department of Energy’s National Energy Technology Research Laboratories have found.

The prolific Marcellus shale may be a rich source for microbial life, which could help refill the important domestic natural gas reservoir by producing methane, scientists at one of the US Department of Energy’s National Energy Technology Research Laboratories have found.

NETL research in the 1980s began to lay the foundation for hydraulic fracturing, which helped open previously inaccessible supplies in the geologic formation in parts of Pennsylvania, New York, and West Virginia.

An effort there now suggests that some species of tiny worker microbes known as extremophiles, living in the extreme conditions of the Marcellus, may also be methanogens, meaning that they produce methane.

This study shakes the general assumption that methane gas from the Marcellus is completely thermogenic, or the result of decomposition reactions triggered by extreme heat and pressure, according to DOE’s Fossil Energy Office, of which the NETLs are a part.

It said that the discovery of these unique microorganisms suggests that at least some of the Marcellus gas is biogenic, resulting as a metabolic byproduct of the microbes. Laboratory tests confirmed that the microbes can produce methane with shale as their sole source of nutrients or combined with fracing fluids as a source of nutrients.

NETL researchers’ new discovery has important implications for natural gas production because biogenic methane has a much more rapid generation rate than methane generated by inorganic thermogenic processes, which take place over millions of years. A biogenic source of methane would mean faster regeneration of natural gas in these shales and offers the potential for secondary gas recovery, FEO said.

Putting the methanogens in shale to work offers another benefit, it added. Most methanogens can consume gas carbon dioxide, a greenhouse gas that can be stored underground to prevent negative environmental impacts. In this sense, CO2 acts as a feedstock for methane production, it explained.

“We’re really encouraged by our results,” said Dr. Yael Tucker, an NETL researcher. “If not all of the gas is thermogenic, then it gives hope that there may be a faster recovery time than expected for the renewal of gas reserves in these reservoirs.

“If an economical way to increase the rate of methane production is found, then recoverable quantities could be produced in only a few years and therefore could make natural gas, which is currently considered to be one of the cleanest fossil energy sources, much more abundant,” she suggested.

The work is not limited to shale. Researchers are now investigating methods to increase methane production in coals using native microorganisms, and are exploring concepts such as adding nutrients to microbe populations to increase their methane-producing reactions, FEO noted.

Contact Nick Snow at [email protected].