In responding to Nancy Wood’s concerns, oil and gas wastewater injection causing earthquakes, it is unlikely to happen here in Idaho. Excessive volumes and pressures for injecting produced waters can trigger tension releases along fault paths. This has been known since the 1970s, when deep injected fluids in north Denver’s Rocky Mountain Arsenal triggered small earthquakes. Well over 150,000 injection wells in our country have never initiated renewed fault movements. The states involved with recent increased earthquakes have limited the volumes and pressures of injection fluids and resolved these problems.
In Idaho, injection wells would be at shallow depths and likely into the same rock layers from which the fluids were produced. Currently, Idaho has no Class II injection wells. Any future injections wells would be permitted through the EPA. Safely disposing of produced waters from oil and gas wells is important and a significant cost factor in determining ultimate economic volumes of oil and gas produced from a well.
Jim Classen, geologist, Boise
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