Tuesday, March 6, 2018 | 11:20
a.m.-1:00 p.m. | The Summit Club, 30th Floor, Ballroom
Jeremy Boak, Oklahoma Geological Survey
Topic: "Patterns of seismicity in Oklahoma: Geology matters"
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Oklahoma experienced on average 1.6 earthquakes of Magnitude 3 or greater (M3.0+) from the 1980s through 2008. Since then, seismicity increased to 903 M3.0+ earthquakes in 2015, then declined to 623 in 2016, and ~320 in 2017. >95% of these earthquakes occur over <20% of the area of Oklahoma. Seismic moment peaked in 2016, with three M5.0+ earthquakes, unprecedented in Oklahoma’s recorded history. A recent issue of Seismological Research Letters highlights studies of the September 3, 2016 M5.8 Pawnee earthquake, the largest recorded in Oklahoma.
Rising seismicity is attributed to increased injection of saline formation water into underpressured and permeable Arbuckle Group sedimentary rocks, which lie directly on Precambrian crystalline basement. This water came primarily from high water cut wells in the Hunton and Mississippian Limestone plays, with earthquake pulses beginning in 2009 and 2013, respectively. Pressure communication from the Arbuckle Group to faults in the basement is interpreted to have reduced stress on the faults. Stress reduction allows faults aligned favorably with respect to the regional stress field (SHMax = N 85° E) to generate earthquakes. Poroelastic effects have recently been interpreted to play a role as well.
Reduction in earthquake frequency appears to result from a 1.4 million barrel per day decrease in injection in ~700 Arbuckle disposal wells in the area. These reductions occurred in part due to 1) production decline from/shutting in of wells because of the significant oil price drop in 2014 - 2015, and 2) directives of the Oklahoma Corporation Commission following a position paper by the Oklahoma Geological Survey attributing seismicity to injection. This talk will discuss the evolution of Oklahoma seismicity, regulatory actions taken to reduce it, and investigations of earthquakes outside the main Area of Interest apparently in location and time with oil and gas well completion activity.
Jeremy Boak started as Director of the Oklahoma Geological Survey in July 2015. He served as the Co-Chair of the Oil Shale Symposia, 2006-2015, a role he started as Director of the Center for Oil Shale Technology and Research (COSTAR) at the Colorado School of Mines.
He was an environmental and nuclear materials project manager at Los Alamos National Laboratory, and manager for performance assessment of Yucca Mountain at the U. S. Department of Energy (DOE) in Nevada. Dr. Boak was an exploration geologist at ARCO Oil and Gas, Inc., in Anchorage, Denver, and Bakersfield.
He received his doctorate in Geological Sciences from Harvard University, for work on the 3.8 billion year old Isua supracrustal suite, West Greenland. He received AB and MS degrees from Harvard and an MS from the University of Washington, all in Geological Sciences.
Dr. Boak is married to Anna Stafford, a petroleum geologist and oil finder, and has a stepson Chris who plans to return to school this year in engineering.