A unique way to gather natural gas resources may offer a side benefit
AUSTIN—A research paper published this summer suggests that injecting air and carbon dioxide into methane-hydrate deposits buried far beneath the Gulf of Mexico could be a way to tap into expansive natural gas resources. The process also could ameliorate the effects of climate change by trapping carbon dioxide underground rather than releasing it into the atmosphere.
“Nitrogen-Driven Chromatographic Separation During Gas Injection into Hydrate- Bearing Sediments” was published in the journal Water Resources Research. The research was funded by the University of Texas Institute for Geophysics.
Researchers used computer models and complex algorithms to simulate the results when mixtures of air and carbon dioxide are injected into a methane-hydrate deposit, an ice-like, waterrich chemical compound that forms naturally in low-temperature/high-pressure environments, which includes such areas as the Arctic and deep in the Gulf of Mexico.
In their paper, the authors demonstrated that a process in which one type of molecule trapped in methane hydrate is exchanged for another (called “guest molecule exchange”) is a two-stage process—not a single, simultaneous process, as it was previously thought to be. That shift in understanding led to computer models that could more accurately simulate the chemical processes at work.
First, nitrogen breaks down the methane hydrate. Second, the carbon dioxide crystalizes into a slow-moving wave of carbon dioxide hydrate behind the escaping methane gas. Computer simulations suggest that the process can be repeated with increasing concentrations of carbon dioxide until the reservoir becomes saturated.
The implications of this research are significant. According to estimates cited by UTIG, methane released from hydrate deposits found beneath the Gulf of Mexico could fuel the country for hundreds of years.
While the researchers stress that “our results are theoretical and should be validated experimentally,” lead author Kris Darnell believes the findings could help solve the challenges of energy security and carbon storage. “Our study shows that you can store carbon dioxide in hydrates and produce energy at the same time,” he said. “We’re now openly inviting the entire scientific community to go out and use what we’re learning to move the ball forward.”
This is not the first time hydrate deposits have been proposed for carbon dioxide storage. Earlier attempts either failed or produced unimpressive results. The appeal of this study’s approach is that it proposes extracting natural gas from methanehydrate deposits and at the same time storing carbon dioxide in a deep environment where it is unlikely to be released into the atmosphere and contribute to climate change.
The Jackson School and the UT Hildebrand Department of Petroleum and Geosystems Engineering are currently testing the study’s method in a specialized facility in the Jackson School, one of the few facilities in the world that can store and perform tests on methane hydrates. The work is being led by Peter Flemings, a Jackson School professor and senior UTIG research scientist, and David DiCarlo, a professor in the Hildebrand Department. Both are co-authors, with Darnell, on the paper.