State of the Science: Triggered Seismicity in Oklahoma

Kyle E. Murray, PhD

Presents:

National Association of Insurance Commissioners (NAIC) Center for Insurance and Policy Research (CIPR) Event

Chicago, IL August 14, 2015

• earthquake – sudden motion of Earth resulting from the abrupt release of accumulated strain (aka: potential energy)

• fault – a surface or zone of rock fracture along which there is displacement, from a few centimeters to a few kilometers in scale

What is an Earthquake?

Earthquakes of Magnitude ≥2.8 from 1/1/1970 to 1/1/2009

http://ds.iris.edu/ieb/index.html

Relationship between frequency and magnitude of natural seismicity

#𝑀𝑎𝑔 2

#𝑀𝑎𝑔 3 = 10

Earthquakes of Magnitude ≥2.8 from 1/1/2009 to present

http://ds.iris.edu/ieb/index.html

Number of Earthquakes recorded by OGS, Jan 2009–Oct 7, 2014

Data from OGS Earthquake Catalog

M5.6 Nov 6, 2011 Prague, Lincoln Cnty

M4.8 Nov 5, 2011 Lincoln Cnty M4.8 Nov 8, 2011 Lincoln Cnty

M4.5 Dec 7, 2013 Oklahoma Cnty M4.5 Mar 30, 2014 Logan Cnty M4.5 Jun 16, 2014 Oklahoma Cnty

#𝑀𝑎𝑔 2

#𝑀𝑎𝑔 3 = 1

OGS Statements on Seismicity

May 2, 2014 Joint Statement with USGS

Record Number of Oklahoma Tremors Raises Possibility of Damaging Earthquakes

http://earthquake.usgs.gov/contactus/golden/newsrelease_05022014.php

“As a result of the increased number of small and moderate shocks, the likelihood of future, damaging earthquakes has increased for central and north-central Oklahoma.”

Fluid Injection and Seismicity in Oklahoma

http://wichita.ogs.ou.edu/documents/OGS_Statement-Earthquakes-4-21-15.pdf

“Very likely that the majority of recent earthquakes, particularly those in central and north-central Oklahoma, are triggered by the injection of produced water in disposal wells.”

Ellsworth, 2013

• More than 100 years of oil and gas production

• Peak oil prod. of ~270 MMBO in 1927

• Peak gas prod. of ~376–399 MMBOE in 1990

• Oil production of ~128 MMBO in 2014

• Gas production of ~385 MMBOE in 2014

History of Oil and Gas Production for Oklahoma

Zones of Exploration & Production (E&P)

OKCGS Shale Shaker (Murray and Holland, 2014) 11

O&G Wells Completed (2010 – May 2014)

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Wa

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“We are drilling water wells.”

From 2000-2011, newly completed wells in OK’s Mississippian averaged: • 7.4 bbl of H2O produced for 1 bbl of oil • 9.8 bbl of H2O produced for 1 bbl oil equivalent gas

(Murray, 2013)

Oil and Gas Production from the Mississippian Zone

Cumulative production by County, 1963–2014

H2O:Oil 7.4 H2O:Gas 9.8

Estimated Volumes of SaltWater Co-Produced from the Mississippian

What do we do with the co-produced saltwater?

SaltWater Disposal (SWD) Wells

(Murray, 2015)

Fig 4 Map of SWD Class II UIC wells, chart of SWD vols by county

(Murray, 2014)

Geologic Provinces, Faults and Located Earthquakes Mag >= 2.8

Earthquakes from OGS Earthquake Catalog thru Jul 1, 2015; Northcutt and Campbell, 1995; Holland, 2015

Faults are compiled from industry contributions and published literature, more than 15,000 features at present

Factors (Faults) to Evaluate Potential for Triggered Seismicity

• Presence of a fault (pre-existing critically or near critically stressed)

• Type of fault (not all faults are created equal, majority of triggered seismicity occurs along

strike-slip faults, pressure perturbation required to trigger fault slippage will differ)

• Size of fault (those that extend into the basement are more significant)

• Dip of fault (steeply dipping strike-slip faults are more likely to be triggered)

• Orientation of fault (strike-slip faults striking from 40–60° and 130–150° are most likely to

slip during recent earthquakes in Oklahoma)

strike-slip fault OF1-2015

Darold et al., 2015

Maximum Horizontal

Stress

Active Fault Orientations 2014

Differentiating between Natural and Induced Seismicity

(1) Induced seismicity in a geothermal field has different characteristics than a tectonically-active geothermal field.

(2) Recent Oklahoma earthquakes behave differently compared with historic Oklahoma earthquakes and plate boundary earthquakes in the western US.

Seismic activity differs within geothermal field vs. outside field

Injection wells

Production wells High b-value

Different clustering type

Cheng and Chen, in prep for GRL

Example of research in the Salton Sea Geothermal field in southern California

Injection zone

Recycle &

Reuse

Salt Water

Disposal

Summary and Forecast

SWD Seismicity

Fluid extraction

2014 2009 2019

Recycle & Reuse