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AReviewofTrafficLightProtocolforInducedSeismicityandItsEffectivenessinCanada

Honn Kao

GeologicalSurveyofCanada,NRCanAlsoatSchoolofEarthandOceanSciences,UniversityofVictoria

3 GeoscienceBC4 WesternUniversity

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Outline

§ DefinitionofaTrafficLightProtocol(TLP)§ HistoricaldevelopmentoftheTLPforinducedseismicity(IS-TLP).§ IS-TLPinCanada.§ Casestudiesofred-lighteventsinBCandAB.§ Summaryandimplications.

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WhatisaTrafficLightProtocol?§ ATLPisasite-specific,real-time,riskmanagementsystem

withmultiplediscreteresponselevels.§ EachTLPlevelisdeterminedusingobservablecriteriaand

invokesspecificactionsdesignedtomitigatetheassociatedrisk.

§ MostIS-TLPsworkbyprovidingafeedbacksystemthatallowsforanoperationalresponsetothenearbyoccurrenceofseismiceventsexceedingaprescribedsetofcriteria.

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IS-TLPfromRegulator’sPerspective§ Identification,analysis,andtreatmentofseismicrisk

associatedwithinducedseismicity.§ IS-TLPisconsideredareactive riskmanagementtoolinthe

“treatment”catagory.§ Ingeneral,seismicdamagestartswhenpeakground

acceleration(PGA)exceeds5–10%ofEarth’sgravity(g).§ Ultimategoal:Toensureaquickandeffectivereductionin

boththenumberandsizeofinducedearthquakes.

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IS-TLPfromOperatorandServiceProvider’sPerspective§ CAPPPublication2012-0024“CAPPHydraulicFracturing

OperationPractice:Anomalousinducedseismicity:assessment,monitoring,mitigationandresponse”

§ IS-TLPispartofthe“monitoring,mitigationandresponse”category.

§ Fortheindustry,IS-TLPispartofthedecision-makingprocess.Thus,itmustbeeasytounderstand,communicate,develop,andimplement.

§ Ultimately,theeconomicrealityisthebottomline.

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TheFirstIS-TLP§ Proposedfortheoperationsofhydraulicstimulationsof

enhancedgeothermalsystemsineasternElSalvador,CentralAmerica(Bommer etal.2006).

§ Basedonpeakgroundvelocity(PGV).§ Green:Groundmotionbelowthethresholdofgeneral

detectability,ortheoccurrencerateofseismicitylowerthanthealreadyestablishedbackgroundlevel.

§ Amber:Groundmotioncanbefelt,butdamageisunlikely.§ Red:Damagetobuildingsisexpectedtosetin.

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IS-TLPinEurope§ EnhancedGeothermalSystem,Basel,Switzerland(Haringetal.,2008).

§ Green:PGV<0.5mm/s,ML <2.3,nofeltreport(Proceedasplanned)§ Yellow:PGV≤2.0mm/s,ML ≥2.3,fewfeltreport(Informregulators,stop

increasingrate)§ Amber:PGV≤5.0mm/s,ML ≤2.9,manyfeltreports(Reducepumpingrate)§ Red:PGV>5.0mm/s,ML >2.9,generallyfelt(Stoppumping,bleedwells)

§ HydraulicFracturingofShaleGas,UK(https://www.gov.uk)§ Green:ML ≤0.0(Proceedasplanned)§ Amber:ML between0and0.5(Proceedwithcaution,lowerrates,

intensifymonitoring)§ Red:ML >0.5(Suspendinjectionimmediately)

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IS-TLPinUSA§ CO(Wongetal.,2015)

§ Yellow:Feltatthesurface(Modifyoperations)§ Red:ML ≥4.5(Suspendoperations)

§ OK(Stoplight System,http://earthquakes.ok.gov)§ Escalatingreviewofoperator’smitigationproceduresasML ≥2.5,≥3.0.

SuspendoperationswhenML ≥3.5.§ OH(Brudzinski etal.,2017;Dade,2017)

§ ML <1.5(Proceedasplanned)§ ML ≥1.5(Informregulator)§ ML between2.0and2.4(Modifyoperations)§ ML ≥2.5(Temporaryhaltcompletionsonlateral)§ ML ≥3.0(Suspendoperation)

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IS-TLPinAB,Canada§ SubsurfaceOrder#2,issuedonFebruary19,2015.

§ ApplicabletotheDuvernay ZonewithintheFoxCreekarea.§ Green:ML <2.0(Proceedasplanned)§ Yellow:ML between2and4within5kmofaninjectionwell

(ImmediatelyreporttoAER,implementmitigatingplan)§ Red:ML ≥4within5kmofaninjectionwell(ImmediatelyreporttoAER

andceasehydraulicfracturingoperations)

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IS-TLPinBC,Canada§ Section21.1oftheDrillingandProductionRegulation(since

June2015,presentedassite-specificpermitconditionsinceOctober2012).§ Astoplightsystem,noescalatinglevels.§ ApplicabletoallinjectionoperationsinBC.§ Red:ML ≥4within3kmofthedrillingpad,oragroundmotionfeltonthesurfacebyanyindividualwithinthe3kmradius(Suspendoperations).

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MajorDeficienciesofMagnitude-basedIS-TLP§ Possibleconfusionduetomagnitudeuncertainty.

§ Differentscalesand/ormethodology(ML,Mw,Mn,etc.)§ Differentchoice/availabilityofdata(localarrayvs.regionalnetworks)§ Differentsourcecharacteristics(momentscaling,stressdrop,focal

mechanism)§ Differentattenuation/distancecorrections§ Differentsiteeffects

§ Notlinkedtotheimpact/consequencesofreportedevents.§ Completelyignoreotherpotentialusefulindicators(e.g.,changeof

earthquakeoccurrencerate,migrationofhypocenters,correlationwithgeologicalstructures).

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DesignatedGroundMotionMonitoringAreasinBC§ Newpermitconditionforwellsintwodesignatedareas.§ Requirepresenceofadequatemonitoringofgroundmotionduring

hydraulicfracturing.§ Minimumof1groundmotionmonitorwithin3kmofthe

commondrillingpad.§ Instrumentwithadynamicrangeof+/-2gandaminimum

detectabilityof0.02g.§ Submitgroundmotionmonitoringreportwithin30daysof

completion.§ Seismicdataforanygroundmotionsexceeding0.02gmustbe

submitted.

(BCOGCIndustryBulletin2016-19)

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DistributionofRegionalSeismicityinnortheastBCandwestAB

• 4919eventsintotal.• 3030(~62%)occurredinthedesignated

monitoringareas.• Green:~81.5%,Yellow:~18.3%,Red:<0.2%

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Red-Light EventsinBCandAB§ 1.August4,2014,Mw 4.5(ML 4.1)

§ 2.January23,2015,Mw 4.4(ML 4.1)*Mw 3.6(Schultzetal.,2017).

§ 3.June13,2015,Mw 4.6(ML 4.3)*Mw 3.9(Wangetal.,2016),ML 4.4(AGS).

§ 4.August17,2015,Mw 4.6(ML 4.9)

§ 5.January12,2016,Mw 4.4(ML 4.6)*Mw 4.1(Schultzetal.,2017),ML 4.8(AGS).

§ 6.July12,2016,Mw 3.9(ML 4.0)

15Event1,Mw 4.5(ML 4.1)

August4,2014northernMontney,BC

§ ActiveHFandWDduring7/25– 8/07.§ Oneyellow-light (Mw 3.8)event

occurredon7/30.§ Thered-lighteventoccurredwith

reducedinjectionrateandpressure.§ Prior,during,andpost-injection

earthquakeratesare0,0.14,and0eventperday,respectively.

§ NomoreM4+eventafterwards.

16Event2,Mw 4.4(ML 4.1)

January23,2015FoxCreek,AB

§ ActiveHFduring12/17– 1/10.§ 1green- and3yellow-lightevents

duringthelast5daysofinjection.§ Seismicitycontinuedafterthe

completionofHFfor2moreweeks.§ Prior,during,andpost-injection

earthquakeratesare<0.01,0.32,and0.21 eventsperday,respectively.

§ AnotherM4+eventaboutayearlater.

§ Aclearcaseof”delayed”triggering.

(Schultzetal.,2017;Wangetal.,2016)

17Event3,Mw 4.6(ML 4.3)

June13,2015FoxCreek,AB

§ ActiveHFduring5/22– 6/07at6nearbywells.

§ Amongthehighestdailyinjectionvolume.

§ Oneyellow-lighteventoccurredon5/27.

§ Prior,during,andpost-injectionearthquakeratesare0,0.18,and0.01 eventperday,respectively.

§ NomoreM4+eventafterwards.§ Anotherexampleof“delayed”

triggering.

(Schultzetal.,2017)

18Event4,Event4,Mw 4.6(ML 4.9)

August17,2015northernMontney,BC

§ ActiveHFandWDduring8/11–8/28.

§ Onegreen butNO yellow-lighteventoccurredsincetheinjectionbeganbeforetheMw 4.6event.

§ Seismicitycontinuedfor~oneweek.

§ Prior,during,andpost-injectionearthquakeratesare0.03,0.59,and0.19 eventsperday,respectively.

§ NomoreM4+eventafterwards.

(Babaie Mahani etal.,2017a,2017b)

19Event5,Mw 4.4(ML 4.6)

January12,2016FoxCreek,AB

§ SamegeneralareaoftheJanuary23,2015,Mw 4.4,red-lightevent.

§ ActiveHFstartedon1/04,stoppedrightafterthered-lightevent,neverresumed.

§ Twoyellow-lighteventsoccurredon1/09and1/10.

§ Prior,during,andpost-injectionearthquakeratesare0.08,1.11,and0.21 eventsperday,respectively.

§ NomoreM4+eventafterwards.ButscatteredM<4seismicitycontinuedtilltheendofourstudyperiod.

(Schultzetal.,2017;Wangetal.,2017)

20Event6,Mw 3.9(ML 4.0)

July12,2016northernMontney,BC

§ InitiallyreportedML =4.0,laterrevisedtoMw =3.9

§ ActiveHFstartedon7/08.§ Noeventoccurredbeforethis

red-lightevent.§ Prior,during,andpost

earthquakeratesare<0.001,0.6,and0.23 eventsperday,respectively.

§ NomoreM4+eventafterwards.

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KeyObservationsAboutRed-LightEventsinBCandABKeyFeatures Event1

(BC)Event2(AB)

Event3(AB)

Event4(BC)

Event5(AB)

Event6(BC)

Totalnumberofeventsduringinjectionstage 2 12 4 10 10 3

Precursoryseismicityduringinjectionstage YLE YLE+GLE YLE+GLE GLE YLE+GLE None

Rateofseismicitybeforethestartofinjection 0.00 <0.01 0.00 0.03 0.08 <0.01

Rateofseismicityduringtheinjection 0.14 0.32 0.18 0.59 1.11 0.60

Rateofseismicityaftertheinjection 0.00 0.21 0.01 0.19 0.21 0.23

Seismicityrespondingtoinjectionadjustment Yes N/A N/A Yes Yes Yes

Followedbyalargereventcausingdamage No No No No No No

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SummaryandImplications§ AnIS-TLPbasedonescalatingmagnitude(green –>yellow –>red)ismoreapplicabletoAB

thanBC.

§ Backgroundseismicitymaybeausefulreferenceinforecastingtheoverallseismicresponsetoinjections.§ Lowpre-injectionseismicityrate~Lowseismicityrateduringinjection

§ Aclearjumpintheseismicityratefromthepre-injectionperiodtotheinjectionperiod,especiallyafter2015.

§ Thephenomenonof“delayedtriggering”(twored-lighteventsinAB)canbeaproblemfortheeffectivenessoftheIS-TLPandshouldbecarefullyconsidered

§ ExistingIS-TLPforinducedseismicityinbothBCandABappeartobeworkinginthesensethatitpreventsanydamagingearthquakes(M>5.5)fromhappening.

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QuestionsorComments?§ Sendyourquestionsorcommentsto

Dr.Honn KaoProjectLeader,InducedSeismicityResearchGeologicalSurveyofCanada(250)363-6625Honn.Kao@canada.ca