quote:
A new method, developed in the United States, could help improve oil output from the tightly packed formations of shale rock. Developed by researchers at Pennsylvania State University, the new oil extraction workflow may improve shale oil recovery up to an additional 15%.

The efficient method could also provide long-term storage for carbon dioxide (CO2) emissions.

Researchers revealed that the workflow was successfully implemented for the Texas Eagle Ford Shale, where it demonstrated improvement in oil extraction, the researchers said, explaining that it can be expanded for application in other shale reservoirs.

The method focuses on improving cyclic CO2 injection, a process in which CO2 is pumped into the reservoir to enhance oil production. Also known as “CO2 huff-n-puff,” the decades-old injection method bolsters extraction from naturally occurring rock formations.

Researchers revealed that these rocks contain microscopic pores, called nanopores, where significant portions of hydrocarbons – the main component of oil — accumulate.

Published in the journal Fuel, the study indicates that a larger volume of injected CO2 leads to greater enhanced oil recovery by enabling deeper penetration into the reservoir and more effective mixing with crude oil.

Furthermore, deep reservoirs containing low gas–oil ratio black oil are especially favorable for cyclic CO2 HnP, as the injected CO2 substantially enhances oil swelling and improves production potential, according to researchers.

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“I would call this one of the best recycling systems in the industry,” said Hamid Emami-Meybodi associate professor of petroleum and natural gas engineering, faculty associate in Penn State’s EMS Energy Institute and lead author.

“Leveraging CO2 to bolster oil production eases environmental impacts, helps fulfill growing energy demand and contributes to the U.S.’ energy independence and security.”

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The lead researchers revealed that during injection, CO2 is fed into the reservoir through a well. Then the well is shut to allow the injected gas to soak for a sufficient period. The gas mixes with the oil, altering its properties and improving oil mobility and extraction, according to the researchers.

By introducing CO2 in oil mixtures at different pressures, the injection process helps force hydrocarbons out of nanopores and to the surface. But the method’s effectiveness varies widely with changing operational conditions, depths and oil types, according to a press release.

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Researchers revealed that the workflow was successfully implemented to optimize and screen cyclic CO2 injection in the Eagle Ford Shale. The workflow can be expanded for broader applications across various types of unconventional EOR projects, according to the study.

Oil produced from shale reservoirs drove record crude output in the U.S. over the past decade, but inefficiencies in extraction often leave as much as 90% of the oil behind.

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My non-engineering mind self finds this kind of stuff fascinating, and very encouraging for continued domestic production. Whether using water or CO2, secondary and tertiary oil recovery has been around for about fifty or so years. However, it's the advances, which have accelerated over the past decade, that the industry is making technology wise that could help recover the remaining oil (cited at as much as 90%) out of those shale reservoirs, at a rate that is still economically feasible.

Very cool!