Post on 11-Nov-2021
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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