COGCC's Lepore: No 'Causative Determination' Yet On Second Greeley Quake
The Colorado Oil and Gas Conservation Commission has ordered a 20 day halt to wastewater injection at a well near the Greeley/Weld County airport. The order follows a second earthquake in the Greeley area, a 2.6 magnitude event June 23.
The first tremor was a 3.2 magnitude earthquake that struck the Greeley area at the end of May. As we've previously reported, a team from the University of Colorado placed a network of seismometers across Weld County to listen for additional shaking and to collect data on the seismic activity's relation to Weld's prolific energy sector.
The well in question is owned by High Sierra Water Service and has been used for exploration and production waste. According to a statement from the COGCC, the CU seismologists "picked up additional evidence of low-level seismic activity near the injection site, including a 2.6-magnitude event."
In that same statement, COGCC director Matt Lepore said it was important to "bring in additional expertise and closely review the history of injection at this site in order to more fully understand any potential link to seismicity and use of this disposal well." He expanded on that comment in an interview aired during All Things Considered and Morning Edition.
What findings did the CU team have after the first earthquake?
“What they saw was some very minor aftershocks, and then as I understand it a cessation of activity, and now here in the last few days they have begun to see very small activity, very small events. When they saw what is now being called a 2.6 event we felt that we needed to take action.
Were the Weld County quakes caused by oil and gas drilling?
“While we think it is the prudent thing to do, to stop injection at this well and do the next steps that I talked about, we are not making yet a causative determination. We want to continue to gather information.”
What could happen after the data is evaluated?
“…one possibility would be resume injection but perhaps do it at a lesser volume than has previously been done. So in other words I guess we might consider ramping up injection while we continue to monitor and see what we see.... If the causative link becomes clearer we could have the well shut in and it would no longer be used as a disposal well, but we’re not at that place yet.”