States consider risk of induced seismicity
The Interstate Oil & Gas Compact Commission and Ground Water Protection Council have teamed up with state oil and gas regulatory agencies and geological surveys to create a work group to discuss the possible association between recent seismic events in several US states and injection wells.
US Environmental Protection Agency data indicate there are nearly 151,000 Class II Underground Injection Control wells across the US that are used to dispose of produced water or to enhance resource recovery.
The Induced Seismicity by Injection work group will collaborate on ways to evaluate the connections between seismic events and injection wells and consider the best ways to minimize risk and improve readiness for seismic events.
The work group initiative is part of a the larger States First effort being led by the State Oil Gas Regulatory Exchange (SOGRE).
State oil and gas regulatory agencies are collaborating through the SOGRE in an effort to stay current with technology and to share innovative practices, procedures, and protocols.
IOGCC said participating states are seeking to include more stakeholders in the discussion, including industry, environmental groups, and the scientific community.
Group updates are set to be made available on the States First website at www.statesfirstinitiative.org.
Oklahoma at risk for major earthquake
The rate of earthquakes in Oklahoma has increased by about 50% since October 2013 and the trend may be linked to the practice of injecting wastewater into deep geologic formations, according to an advisory issued by the US Geological Survey (USGS) and the Oklahoma Geological Survey (OGS).
The agencies said 145 earthquakes of a magnitude 3.0 or greater occurred in Oklahoma from January 14 through May 2, and the central portion of the state faces an increased risk for a damaging magnitude 5.5 or greater quake.
The previous annual record of 109 earthquakes was set in 2013. From 1978 to 2008, the long-term average earthquake rate was two magnitude 3.0 or greater earthquakes per year.
"Important to people living in central and north-central Oklahoma is that the likelihood of future, damaging earthquakes has increased as a result of the increased number of small and moderate shocks," the agencies said in a release.
A USGS study suggests a magnitude 5.7 earthquake that struck near Prague, Okla., in 2011 and led to hundreds of smaller aftershocks was triggered by a smaller quake, or foreshock, linked to wastewater injection wells near a known fault (UOGR print edition, May-June 2014, p. 20).
USGS and OGS researchers are examining the earthquake sequence in relation to nearby injection activities. OGS operates a seismograph network of 32 monitoring stations in Oklahoma, alongside three operated by USGS. Researchers are seeking to understand increased seismic activity in Oklahoma. Work includes quantifying changes in the earthquake rate, assessing the implications of the increased small and moderate earthquake activity for large earthquake hazards, and evaluating possible links between these earthquakes and wastewater disposal wells.