September 8, 2012
In late August, the British Columbia Commission on Oil and Gas issued their findings from a study launched in the summer of 2011 to investigate anomalous seismic activity recorded in a remote area of the Horn River Basin in Northeastern British Columbia between April 2009 and December 2011. Thirty-eight seismic events were recorded during that period. The observed events were minor, ranging in magnitude from 2.2 to 3.8 ML on the Richter scale The activity was unusual because the Canadian National Earthquake Database showed no detected seismicity in the Horn River Basin prior to 2009. The study was undertaken to examine the available evidence to determine if there may be a linkage between oil and gas activities in the region and the observed events. The Commission reviewed hydraulic fracturing and well completion information on wells located near the area of observed seismicity. The dates and times of hydraulic fracturing operations were compared to the dates and times of recorded seismicity events.
The report, Investigation of Observed Seismicity in the Horn River Basin, concluded that the seismicity observed in the study area was the result of fault movement induced by the injection of fluids during hydraulic fracturing activities. The results showed that movement associated with the events was confined to the targeted gas bearing shales.
South of the border, the US Geological Survey (USGS) released findings and presented a paper on the issue at the Seismological Society of America Meeting. USGS scientists investigated recent increase in the number of magnitude 3 and greater earthquakes in the midcontinent of the United States. Beginning in 2001, the average number of earthquakes occurring per year of magnitude 3 or greater increased significantly, culminating in a six-fold increase in 2011 over 20th century levels. USGS’s studies do not suggest that hydraulic fracturing operations cause the increased rate of earthquakes. However, the scientists have concluded that, at some locations, the increase in seismicity coincides with the injection of wastewater in deep disposal wells.
In their preliminary findings, the USGS demonstrates, by several examples, where an uptick in seismic activity is observed in areas where the disposal of wastewater through deep-well injection increased significantly. These areas tend to be in the middle of the country – mostly in Colorado, Texas, Arkansas, Oklahoma and Ohio. Even though the increased number of earthquakes in this region appear to be man-made, it remains to be determined if changes in production methodologies or rate of oil and gas production are the cause of the increase.
Issues continue to be raised by communities and environmental action groups regarding possible health and environmental effects associated with chemicals used in hydraulic fracturing operations, as well as with the potential leakage of fracturing fluids into drinking water aquifers and the discharge of fracturing fluids after use. Currently, hydraulic fracturing operations and associated fluids are covered by state oil and gas regulatory programs, and are not regulated under the Safe Drinking Water Act. Additionally, legislation governing disclosure of fluid composition, permitting requirements for use and disposal, and requirements for preliminary environmental assessments are under development in a number of states relating to development of the Marcellus, Barnett, Black Warrior, Powder River, and Eagle Ford Basins, among others.
Exponent’s Capabilities in Hydraulic Fracturing
Exponent’s engineers and scientists can facilitate the evaluation of all scientific and regulatory aspects of hydraulic fracturing. Our consultants have significant experience working in and consulting for the oil and gas industry, and understand both the technical and operational aspects of the issues.
- Extensive operational knowledge of oil and gas exploration and production activities and their potential environmental impacts.
- In-depth, functional knowledge and expertise regarding petroleum engineering, use of disposal pits and ponds, and hydraulic fracturing fluid use.
- Scientific expertise in environmental and health perspectives, hazard characterization, chemical risk assessment and regulatory policy, and experience with conducting human health and environmental risk, impact, and baseline assessments for the oil and gas industry.
- Active in investigations, education, and research in earthquake science and engineering.
- Proven experience on high-profile projects of national and international significance—often in a dispute resolution setting.
More information on Exponent’s capabilities can be found here
If you would like to review Exponent’s webinar on Earthquakes and Fracking held earlier this year, click here