cause a seismic event,” said Stowe — adding, however, that this
isn’t a common occurrence.
According to Andrew Place, interim director and president of
the Center for Sustainable Shale Development, seismicity is more
of a concern for EGS due to the ongoing nature of the technology,
whereas natural gas enters a site, fracks for the resource and
moves on. “[For natural gas] the strong concern is for disposal
wells, and if you don’t site them carefully and drill in a close
proximity to an existing fault that is highly stressed, you could
set off a substantial seismic event,” he said. This can be avoided
with pre-drill modeling to ensure the avoidance of fracture networks and monitoring for seismic events — similar to the precautions already being taken at the Newberry project site.
Fracking vs Slipping
According to Hollett, the fundamental difference between nat-
ural gas fracking and EGS fracking is the injection process.
The oil and gas industry injects water and a proppant (a mix
of sand and chemicals), at a
very high pressure of around
9,000 psi or more, which
breaks though the rock and
holds the cracks open; other-
wise they would close when
the fuid stops fowing.
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