Multidisciplinary Approach to Identify and Mitigate the Hazard from Induced Seismicity in Oklahoma
Aus n Holland, Randy Keller, Amberlee Darold, Kyle Murray, Steve Holloway, Kevin Crain Acknowledgements
Industry contributors to RPSEA and fault database
Oklahoma Independent Petroleum Associa on (OIPA)
USGS – providing many Oklahoma Secretary of Energy and Environment different temporary Oklahoma Corpora on Commission seismic sta ons
OU Mewbourne College of Earth and Energy
Oklahoma’s Increase in Earthquakes Earthquake rates per year Magnitude 4 or Greater Magnitude 3 or Greater Earthquakes Earthquakes Years 1980-2008
0.1 1.6 20 Year 2009 3 42 Years 67 Year 2010 1882-2008 40 Years Year 2011 2009-2013 427 109 Year 2014 Year 2012
24 Year 2013 Updated Oct. 20, 2014 Year 2014 Earthquake Forecasting • Probability of one or more earthquakes of magnitude (m) over the specified me • Not a predic on, but a forecast Oklahoma Recurrence Rates & Probabilities
Mc=1.9 Mc=2.3
Calculated with a 6 month moving window Oklahoma Earthquakes 2009-2014
Area of greatest increase is about 15% of Oklahoma. Captures areas of significant waste-water disposal wells Cumulative Seismicity in Oklahoma Cumula ve Number of Earthquakes
Oklahoma Geol. Survey www.okgeosurvey1.gov/pages/earthquakes/catalogs.php UIC Class II Injection Oklahoma Earthquakes 2009-2014
Area of greatest increase is about 15% of Oklahoma. Captures areas of significant waste-water disposal wells RPSEA - 4D Integrated Multi-scale Reservoir and Geological Modeling • 4D geophysical monitoring • Localized well-based pressure tests • Goals – Improve model predic ve capabili es – Maintain a suite of progressively updated models – Improved representa on of the preferen al flowpaths – Geomechanical proper es and fault characteris cs in the subsurface OKRaH Seismic Network 3D geologic and geophysical model
• 100,000’s of Wells in central Oklahoma • Geological and geophysical logs combined to build 3D models Geospa ally referenced surfaces Hunton • Incorporated (orange) and basement (brown). into 3D seismic Geologic units are assigned physical proper es velocity models such as from well logs with spa ally varying proper es such as permeability, density, porosity, and velocity. Gravity Observations Provide Constraints on Geologic Models Industry Contribu ng to Enhanced Fault Database All Submitted Faults Interagency Cooperation
Industry, OCC UIC DOE and Data OGS Program State of OK Support
Op mally Oriented Faults
Fault Maps Industry Fault Fault Database Database Earthquake Project Informa on Contributors & OIPA
New Permit & Earthquake Improvements to Monitoring and Seismograph Exis ng Permits Repor ng Network
Reservoir & Injec on and Geomechanical Opera onal Data Addi onal Studies Modeling RPSEA Current Mitigation Steps • Oklahoma Corpora on Commission is the regulator of UIC Class II wells, and have implemented different mi ga on strategies – New rules regarding repor ng of injec on volumes and pressures in the “Arbuckle” – Permit modifica ons; i.e. “Traffic Light System” – Enhanced repor ng requirements in OCC areas of interest, currently 10 km around ML 4+ earthquakes • Not required by rule for non-Arbuckle wells, but operators have complied for requests of greater repor ng – New permits are checked against fault maps and background seismicity Summary
• The rate of seismicity has increased drama cally and so has the seismic hazard • Building large geological and geophysical data sets at varying scales and dimensions • Con nue to provide data products to stakeholders and iden fying new data sources • A greater understanding of physical processes in Oklahoma will help to inform future mi ga on strategies • Mul -agency coopera on has now been solidified in the governor’s Coordina ng Council Abstract Oklahoma has experienced a very significant increase in seismicity rates over the last 5 years with the greatest increase occurring in 2014. The observed rate increase indicates that the seismic hazard for at least some parts of Oklahoma has increased significantly. Many seismologists consider the large number of salt-water disposal wells opera ng in Oklahoma as the largest contribu ng factor to this increase. However, unlike many cases of seismicity induced by injec on, the greatest increase is occurring over a very large area, about 15% of the state. There are more than 3,000 disposal wells currently opera ng within Oklahoma along with injec on volumes greater than 2010 rates. These factors add many significant challenges to iden fying poten al cases of induced seismicity and understanding the contribu ng factors well enough to mi gate such occurrences. In response to a clear need for a be er geotechnical understanding of what is occurring in Oklahoma, a mul -year mul disciplinary study some of the most ac ve areas has begun at the University of Oklahoma. This study includes addi onal seismic monitoring, be er geological and geophysical characteriza on of the subsurface, hydrological and reservoir modeling, and geomechanical studies to be er understand the rise in seismicity rates. The Oklahoma Corpora on Commission has added new rules regarding repor ng and monitoring of salt- water disposal wells, and con nue to work with the Oklahoma Geological Survey and other researchers.