Induced Seismicity Intersection of Science, Public and Regulation Fred Aminzadeh, Don Paul University of Southern California November 5, 2013 Long Beach, CA

Summary What is Induced Seismicity Scientific Foundation intersection of the science, the public, and the regulation Hydraulic Fracturing / SFIP Induced Seismicity Consortium

1. Earthquake magnitude and Intensity 2. Induced seismicity: ways to ‘unlock’ a fault 3. What conditions are required to create large earthquakes? Outline

Zoback & Gorelick 2012 Seismic moment and fault area

Ellsworth 2013

Seismic moment and energy Light earthquake, some damage Minor earthquake, Felt by humans

Definitions  SFIP – Subsurface Fluid Injection and Production, including: – Hydraulic Fracturing  Triggered Seismicity – SFIP accounts for only a small fraction of the stress change associated with the earthquakes. – Pre-existing tectonic stress plays the primary role  Induced Seismicity – SFIP accounts for most of the stress change or energy to produce the earthquakes

Accurate and Consistent Assessment of Risk is Essential for all SFIP What is the largest earthquake expected? Will small earthquakes lead to bigger ones? Can induced seismicity cause bigger earthquakes on near by and distant faults? Even small felt (micro)earthquakes are annoying. Can induced seismicity be controlled? What controls are (will be) in place to mitigate future induced seismicity? What is the plan if a large earthquake occurs? Long term response versus short term response

 Thermal stress  Chemical alteration of slip surfaces  Pore pressure increase Mechanisms Production inducedInjection induced Effective stress changes  Ambient stress variations  Volume change (subsidence, inflation)

Elevated Fluid Pressure: Reduces effective normal stress on fault, lowering resistance to shearing. Implies that if pressure balance can be maintained seismicity can be controlled Role of Fluid Pressure in Earthquake generation For a microearthquake to occur one must exceed the critical shear stress on the fault:   c +  (  n - p) Normal (clamping) Stress = Stress =  n In situ Shear Stress Stress  Water/fluid pressure in fault = p Fault  = coefficient of friction on fault

Introduction to Induced Seismicity fracture treatment / Fluid Injection / CCS Increase in stress and pore Pressure Decrease the stability of existing weak planes (natural fractures, bedding planes) slip and fail, similar to earthquakes along faults slippages emit elastic waves (stimulated seismicity ) Induced Seismicity Data Base Models-IS Risk Maps

τ = μσ, τ = μ(σ-p), where p is the pore pressure and σ-p the effective normal stress Induced seismicity mechanisms: Fault activation

Scholz 1998 Frictional properties of faults

What is Fracking  Hydraulic fracturing is stimulating rock layers by a pressurized liquid to facilitate release of gas and oil.rock layers  It creates fractures from a wellbore drilled into reservoirwellbore

Three main issues  How to assess risk  How to minimize risk  How to use Induced seismicity effectively

ANALYSIS OF 44 YEARS PRODUCTION/INJECTION Horizontal Stress (Effective) Vertical Stress(Effective) Induced seismicity occurs near the ground surface, close to the wells, and below the wells. Near the wells stress reduction due to cooling shrinkage causes seismicity. Near the ground surface, below the wells stress from the shrinking reservoir causes IS Failure Potential

2) Earthquake Shaking model For a given earthquake rupture, this gives the probability that an intensity- measure type will exceed some level of concern 1) Earthquake Rupture Forecast Gives the probability of all possible earthquake ruptures (fault offsets) throughout the region and over a specified time span Two main model components: Physics-based “Waveform Modeling” Empirical “Attenuation Relationships” Seismic Hazard Analysis

Ingredients to create large Magnitude earthquakes Velocity weakening friction ● Velocity weakening friction ● Large enough fault area available ● High ambient stress level ● Fault close to failure strength ● Static stress triggering?

Keranen et al Seismic events in Prague, OK, 2011 Triggered by static stress change? M~ Induced by fluid injection M ~4.7 Depth: 4-5 km

Induced seismic events identified by proximity to injection well Waste fluid deposit in gas reservoir, Sichuan province China Lei et al. 2013

Criteria for fault reactivation  weak zones (faults) are present  critically stressed fault  (susceptible to remote triggering)  favorable orientation relative to injection well  (high) fault permeability, fluid path way

MEQ DERIVED PROPERTIES Brawley Field Fracture Characterization

INTERBrawley Field Fracture Characterization PRETATION (2) High extensional stress and high FZI values mapped at horizons of interest along two wells with known conductive fractures. We observe high V E to map with high FZI close to wells but not necessarily at other locations (due to dependence on other properties)

Brawley Field Fracture Characterization ERPRETATION (3) Extensional stress, discontinuity, edge and gradient mapped close to sample wellbore at horizon of interest. We observe major change in stress close to identified edge boundaries flanked by major discontinuities. FZI mapped with discontinuity and extensional stress (vector) map. We observe major changes in stress regime close to identified discontinuities along with potential flow regime close to wellbore at horizon of interest.

HYBRID FZI ATBrawley Field Fracture Characterization TRIBUTE MAPPING (ANN) Training data extraction Sample Well FZI

Some of the USC-ISC Ongoing Work  Real time monitoring  Regional Studies  San Joaquin Valley, CA,  Youngstown, Ohio and  Prague Oklahoma  Generating IS hazard maps  Geo-mechanical modeling:  Laboratory experiments isc.usc.edu

Regional Studies: San Joaquin Valley, CA,  B-Value Analysis  Fault related events VS SFIP  Correlating Seismicity and SFIP  Hazard maps Santa Maria Valley field seismicity and reported SFIP

Regional Studies: San Joaquin Valley, CA,  Spatial variations in the magnitude of completeness  Oil fields are highlighted in black and labeled according to the legend on the right.  The gray triangles mark the position of seismic stations.

California Oil an Gas Field Seismicity,

Regional Studies: Youngstown, OH, Historic seismicity in the state of Ohio. Kim, Work flow and goals of subsurface structure analysis in Youngtown, Ohio.

Regional Studies: Prague, OK, 2011:  Three M>5.0 earthquakes occurred near Prague, Oklahoma in November  The USGS and University of Oklahoma deployed both local and regional arrays of seismometers to conduct various analysis related to seismic hazard within OK: Sumy et al., 2013, Van der Elst et al. 2013

Geo-mechanical modeling  Model the stress change associated with hydraulic fracturing to assess risk of microseismic activities  Ethe reservoir permeability from Geomechanical Seismicity Based Permeability Characterization (GSBRC) model to a heterogeneous anisotropic reservoir.

Laboratory experiments Examine Fault activation due to fluid-injection in an analogue borehole. Initially pore pressure increase results in fracture of intact rock The fault starts to slip once the effective stress reach a threshold

Induced Seismicity: Recent Issues High-profile press coverage and congressional/regulatory inquiries have focused attention on induced seismicity related to energy projects in the U.S. and Europe – The Geysers, CA; Basel, Switzerland; Soultz, France; Landau, Germany – Oil and gas: Texas, shale gas sites – CO 2 sequestration sites (various) However, industry has successfully dealt with induced seismicity issues for almost 100 years (mining, oil and gas, waste injections, reservoir impoundment, etc.) How does one assess hazard risk and economic risk – Investors want to know – Regulators want to know – Seismicity related to injection cannot be assessed the same as natural seismicity – Scale and distance of influence Seismicity is also be useful as a resource management tool – Geothermal, Oil and Gas, CO2 Seq ??

Induced Seismicity: observations on the intersection of science, policy, and the public Framing the Induced Seismicity issue: – Adds to the ongoing discussions with respect shale resource development and its impact – Seismicity, whether induced or naturally occurring, is poorly understood by most stakeholder groups – When complex issues involve extensive political and societal engagement, a strong science base is almost never sufficient to carry the debate

Examples (largest events) Mag Date Reservoir Impoundment – Hoover, USA earliest recognized case of RIS – Koyna, India structural damage, 200 killed – Aswan, Egypt largest reservoir, deep seismicity Mines and Quarries – Wappingers Falls, NY – Reading, PA – Belchatow, Poland (coal) Oil and Gas fields – Long Beach,CA ’s – Dallas - Ft worth – Lacq, France ~4various Gas extraction Injection related – Denver ’s – Geothermal ’s

Understanding of Induced Seismicity Technical – One of few means to understand volumetric permeability enhancement/fluid paths – Proper uses could optimize reservoir performance Policy/Regulatory – Potential to side track important energy supply – Technology must be put on a solid scientific basis to get public acceptance – Accurate risk assessment must be done to advance energy projects

Zone of influence from potential US earthquakes

Induced Seismicity: observations on the intersection of science, policy, and the public Science and technology opportunities: – Develop an integrated approach and community for the supporting science and technology (earthquake seismology + petroleum geology /geophysics + drilling / production engineering) – Increase the current state of geological knowledge, including updated regional /local fault mapping, for areas of potential resource development and disposal well operations. – Increase the current state of seismic measurement and risk assessment for areas of potential resource development and disposal well operations.

Induced Seismicity: observations on the intersection of science, policy, and the public Policy and regulation opportunities: – Induced Seismicity Risk Assessments from proposed drilling, production, and disposal activities, especially including the impact from likely surface ground motions. – Well planning and approval processes which assesses the interaction of well trajectories, injection and fracturing operations with the known natural fault system and relevant geological conditions. – Development and implementation of seismic monitoring plans for areas of active development, especially including disposal wells.

Induced Seismicity: observations on the intersection of science, policy, and the public Public outreach and communication opportunities: – Support and engagement with public earthquake education and preparedness programs and processes – Properly framing Induced Seismicity into the larger discussion and debate on hydro-fracturing and resource development General comment: – The inherent linkage of development to local / regional geological conditions clearly implies that state geological and regulatory agencies need to lead on setting and supervising regulatory and permitting processes.

Policy Needs Supply stakeholders with guidelines (protocols/best practices) – Update as technology progresses – Follow technical and community/regulator interaction Community Interaction – Supply timely, open, and complete information – Educate operators on importance of public outreach – Technical based risk analysis Develop risk based procedure for estimating potential mitigation requirements (Adapt Seismic hazard analysis for induced seismicity applications) – Probabilistic – Physics based

What should/could be done? –Research Needs Quantify relation between seismicity and permeability enhancement Improve means to quantify the relation between stress change and seismicity rate? Is there time dependence or stressing rate dependence in stress-seismicity rate changes/ or is the theory of effective stress all we need to know? Determine the role of slip-dilatancy (slip-permeability) in fault zones in EQ generation? Determine role of mechanical processes (fault healing, permeability reduction) versus other changes in the induced seismicity generation – What do we need to know about fault zone poroelasticity? – What do we need to know about chemical processes? Do induced earthquakes follow the same decay relations as tectonic earthquakes in the same province? (why or why not) Active experiments to manipulate seismicity without compromising production – reservoir performance assessment – integrated reservoir analysis Dedicated test sites for exploring research issues?

Should Fracking Stop? Extracting gas from shale increases the availability of this resource, but the health and environmental risks may be too high. POINT Yes, it’s too high risk Natural gas extracted from shale comes at too great a cost to the environment, Say Robert W. Howarth and Anthony Ingraffea. COUNTERPOINT No, it’s too valuable Fracking is crucial to economic stability; the benefits outweigh the environmental risks, says Terry Engelder. A drilling operation in Bradford County, PA

Bottom line Technical issues – Further understanding of complex interaction between stress, temperature, rock and fluid properties (we do not fully understand the linkage between all of the subsurface parameters Community Interaction/Regulatory – Supply timely, open, and complete information – Consistent science based “rules”

Balance  Water supply contamination  Increased induced seismicity  Land / Water use challenges  Potential to overwhelm community infrastructure  Continued reliance on fossil oil Concerns to Address Possible Steps  More Science  More Disclosure  Understand economic impacts of extreme measures  Improve Education/Outreach  Listen to both sides To Frack or not to Frack, That is the Question Science is the Answer: Vincit Veritas (Truth Prevails)

Acknowledgements  NAS Induced Seismicity Report, June 2012,  WSPA, for partial support of Monterrey shale California Economic impact study  Sponsors of USC Induced seismicity Consortium (ISC), More at isc.usc.edu gen.usc.edu isc.usc.edu gen.usc.edu