“A dozen earthquakes in northeastern Ohio were almost certainly induced by injection of gas-drilling wastewater into the earth,” Ohio oil and gas regulators said today.

Citizens respond to speakers during a community forum in Youngstown, Ohio, to discuss seismic activity related to deep wastewater injection wells. Source: AP.

These quakes weren’t caused by the original fracking — that is, by injecting a fluid mixture into the earth to release natural gas (or oil). It was caused by a Class II disposal well used to reinject the resulting brine deep underground. That reinjection is banned in some states.

The Ohio Department of Natural Resources (ODNR) has issued a preliminary report “on the relationship between the Northstar 1 Class II disposal well and 12 Youngstown area earthquakes” (news release here). They spell out what happened and the steps they will take to make sure it doesn’t happen again.
Specifically, ODNR found:

Geologists believe induced seismic activity is extremely rare, but it can occur with the confluence of a series of specific circumstances. After investigating all available geological formation and well activity data, ODNR regulators and geologists found a number of co-occurring circumstances strongly indicating the Youngstown area earthquakes were induced. Specifically, evidence gathered by state officials suggests fluid from the Northstar 1 disposal well intersected an unmapped fault in a near-failure state of stress causing movement along that fault.

As fracking has exploded onto the science, it has increasingly been connected to earthquakes — see my November 2011 post, Shale Shocked: “Highly Probable” Fracking Caused U.K. Earthquakes, and It’s Linked to Oklahoma Temblors.

Here are some of the steps ODNR is doing to prevent this from reoccuring:

Requires a review of existing geologic data for known faulted areas within the state and avoid the locating of new Class II disposal wells within these areas;

Requires a complete suite of geophysical logs (including, at a minimum, gamma ray, compensated density-neutron, and resistivity logs) to be run on newly drilled Class II disposal wells;

Requires operators to plug back with cement, prior to injection, any well drilled in Precambrian basement rock for testing purposes.

Requires the submission, at time of permit application, of any information available concerning the existence of known geological faults within a specified distance of the proposed well location, and submission of a plan for monitoring any seismic activity that may occur;

Requires a measurement or calculation of original downhole reservoir pressure prior to initial injection;

Requires the installation of a continuous pressure monitoring system, with results being electronically available to ODNR for review; •

Requires the installation of an automatic shut-off system set to operate if the fluid injection pressure exceeds a maximum pressure to be set by ODNR;

Requires the installation of an electronic data recording system for purposes of tracking all fluids brought by a brine transporter for injection;

In January, the Department of Energy set up a committee to examine the full range of environmental impacts of fracking. I testified to the members and, in addition to raising the issue about methane leakage and global warming, I brought up the earthquake issue.

The committee said that they were indeed aware of this issue and ultimately the seven-member panel released a report of environmental guidelines for the natural gas industry, which included call on more research on “Understanding induced seismicity triggered by hydraulic fracturing and injection well disposal.”

I don’t consider this to be one of the 2 or 3 biggest concerns around fracking, but it is now clear that more study and national standards are needed.