What if we could boost the output of fracked shale wells while simultaneously sequestering greenhouse gases? Sounds too good to be true, right? Well, a group of three scientists from France and Australia published a study this week that suggests, on paper, it might be possible to do just that by using carbon dioxide instead of water to hydraulically fracture shale rock. Bloomberg reports:
The [study’s] three co-authors use sophisticated software that simulates how molecules interact. What they found in their simulation is that while water initially flushes out the gas, eventually it becomes a kind of molecular seal, trapping the gas in the deposit.
“Even if this effect remains to be established experimentally, it seems to explain a number of facts observed in shale plants, such as the rapid decline in productivity curves,” said Benoit Coasne, a materials scientist affiliated with the French National Center for Scientific Research and MIT and an author of the study.
Substitutes for water may do a better job at liberating the gas. Highly pressurized CO2 not only pushes out the methane molecules without creating the seal that water does, but also might stay underground and out of the atmosphere.
First, the caveats: the researchers were quick to point out that this is only theoretical at this point. The carbon dioxide being pumped into these wells would need to be at a high enough pressure to be what’s called “supercritical,” and while supercritical CO2 is already used in other industrial processes (like decaffeinating coffee beans), it adds another layer of complexity to drilling operations and—of course—more costs. Moreover, it would require a steady supply of carbon dioxide.
That said, there’s a lot of promise here. This would pair nicely with carbon capture efforts, as companies working on extracting CO2 from the atmosphere (and thereby mitigating climate change) would have a strong market in which to sell their product. That could go a long way towards making CCS profitable. Then too are the obvious benefits this could have for the shale industry itself: carbon fracking could effectively eliminate the problem of wastewater disposal (and the earthquakes to which that disposal has been linked) while simultaneously upping production rates—a very clear win-win.
It’s far to early to crown this as the Next Big Thing for the shale industry, but remember: it didn’t take long for industry to kick off an American energy renaissance once it figured out how to deploy horizontal well drilling and hydraulic fracturing in rock formations previously thought to be inaccessible. The pace of technological change is accelerating, and in carbon fracking we just might be getting a glimpse at shale’s next innovation.