We argue that, yes, small earthquakes do matter, and their interaction may be an important triggering mechanism to consider. Causal mechanism of injectioninduced earthquakes through. Assessing the manner in which basement faults are likely to respond to pressure perturbations caused by fluid injection is. Recent increases in earthquake occurrence rates in oklahoma have been linked to the injection of large volumes of saltwater, a byproduct of oil and gas extraction. The central united states has undergone a dramatic increase in seismicity over the past 6 years fig. We find that injectioninduced fault slip is plausible within the range of selected model input parameters, with slip favored by low reservoir permeability, low fault permeability, and a favorable. Induced seismicity has become a relevant scientific and social issue suckale, 2009, grigoli et al. Delayed dynamic triggering of disposalinduced earthquakes observed by a dense array in northern oklahoma. We develop theoretical estimates, validated by simulations, of the size of ruptures induced by localized porepressure. There has been a growing realization that the principal seismic hazard from injectioninduced earthquakes comes from those associated with disposal of wastewater into deep strata or basement formations.
Experience of induced seismicity in other geological settings and. We refer to earthquakes that are promoted by anthropogenic activity as induced and to earthquakes that are initiated by transient natural stresses as triggered. While there are several hypothesises linking injected volume to the maximum magnitude. Over this range, the moment release is limited to twice the product of the shear modulus and the volume of injected fluid. Although the rate of seismicity has declined with injection rates, some earthquake sequences remained active in 2018 and new clusters have developed. Fluid injection into the subsurface is associated with industrial. Injection wells can induce earthquakes miles away from the. Although induced seismicity related to underground injection activities was irst observed in the. A criterion to assess the influence of pressure migration along faults article pdf available in tectonophysics february 2018 with 291 reads. A critical issue in seismology is to understand the relationship between earthquakes on various scales, giving the similarities and differences between the large earthquakes that occur on plate boundaries through to the. The results can be used to assess the probability of induced slip on a known fault from a given injectionrelated pore pressure increase. Hough abstract in this study, i consider the ground motions generated by 11 moderate m w 4. The remaining earthquakes are induced by wastewater disposal. Humaninduced earthquak es have become an importan t topic of political and scien.
Review and recommendations for induced seismic mitigation. Frackquakes that are manmade injection induced earthquakes increase sharply in the booming areas of oil and gas field development in the united states of america. Ongoing injection operations in the region should be conducted with these understandings in mind. Induced earthquakes by hot dry rock power generation. Currently used models relating the maximum magnitude of injection induced earthquakes to injection parameters do not incorporate rupture physics. The earthquake was felt in at least 17 states and caused damage in the epicentral region. This report discusses known cases of injection induced seismicity and how and why earthquakes may be triggered, as well as conditions under which the triggering is most likely to occur. A search of the advanced national seismic systemanssearthquakecataloggivesprelim. Mar 21, 2019 the ability to predict the magnitude of an earthquake caused by deep fluid injections is an important factor for assessing the safety of the reservoir storage and the seismic hazard. How is hydraulic fracturing related to earthquakes and.
Triggered earthquakes from hydraulic fracturing clearly demonstrate their is potential for induced seismicity in oklahoma historical earthquakes suggest stresses are sufficient to have triggered earthquakes long injection histories, monthly records and multiple wells complicate the identification of triggered earthquakes from. British columbia oil and gas commission bcogc, 2012. Pdf small earthquakes matter in injectioninduced seismicity. The results can be used to assess the probability of induced slip on a known fault from a given injection related pore pressure increase. Injectioninduced earthquakes are thought to be caused by pressure changes due to excess fluid injected deep below the surface and are being dubbed manmade earthquakes.
Here, we present a modeling approach for simulating seismicity induced by fluid injection in 3d over multiple earthquake cycles. Potential injectioninduced seismicity associated with oil. Earthquakes and injection regional context identified cases of possibly induced seismicity in oklahoma cases from hydraulic fracturing up to 2% of wells completed potential cases of induced seismicity within oklahoma difficulties in identifying induced seismicity from uic class ii wells. Triggering in induced seismic zones could therefore be an indicator that fluid injection has brought the fault system to. Map showing location of the 1987 induced earthquake sequence in northeastern ohio near ashtabula relative to the 1986 earthquakes in lake county 60 a20. The results showed that fluid pressure and heterogeneity can significantly influence injection induced earthquakes.
Increased seismicity is injection induced seismicity caused by porepressure increase along preexisting. Energy of injectioninduced seismicity predicted from in. Induced seismicity potential in energy technologies. Wastewater disposal has been associated with induced earthquakes at a number of sites in the central and eastern united. Wastewater injection and hydraulic fracturing can cause seismicity large increase in seismicity in central and eastern us. May 09, 2018 many of the largest injection induced earthquakes have occurred along faults in basement rock beneath the target injection aquifers barbour et al. Annual earthquakes 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 0. Fluid injectioninduced seismicity considering secondary. The effect of varying fluid injection activities on induced earthquakes through jointenriched finite element analyses conference paper pdf available march 2019 with 66 reads how we measure. Earthquakes in unusual locations have become an important topic of discussion in both north america and europe, owing to the concern that industrial activity could cause damaging earthquakes. Injection induced moment release can also be aseismic. Much attention has been given to reducing injection rate andor volume.
Injection induced earthquakes have, in particular, become a focus of discussion as the application of hydraulic fracturing to tight shale formations is enabling the production of oil and gas from previously unproductive formations. Most of this seismicity occurred away from regionally mapped faults, challenging efforts to constrain the continuing hazards of injection. Enhanced remote earthquake triggering at fluidinjection. Probabilistic assessment of potential fault slip related to injectioninduced earthquakes.
T he injection of fluids into the subsurfacehas been known to induce earthquakes since the mid1960s. Injection induced earthquakes are thought to be caused by pressure changes due to excess fluid injected deep below the surface and are being dubbed manmade earthquakes. There have been limited studies into the role of earthquake interactions between the small. Energy of injectioninduced seismicity predicted from insitu. Probabilistic assessment of potential fault slip related. Results of ongoing multiyear research on induced earthquakes by the united states geological survey usgs published in 2015 suggested that most of the significant earthquakes in oklahoma, such as the 1952 magnitude 5. Injectioninduced seismicity and faultslip potential in. Wastewater injection has induced earthquakes in oklahoma, but the relative importance of operational and geologic parameters in triggering such earthquakes is unclear. Most injection wells are not associated with felt earthquakes. However, the ratio of total induced earthquake energy to water injection energy varied greatly from 0. Induced seismicity provides insight into why earthquake. A classification of induced seismicity sciencedirect.
A brief overview congressional research service 1 introduction human induced earthquakes, also known as induced seismicity, are an increasing concern in regions of the united states where the produced fluids and wastewaters from oil and natural gas. The model is based on the physical processes of fluid pressure and stress diffusion with triggering of the induced seismicity being controlled by coulomb friction. In some cases, the isolation of a single mechanism is simple e. However, few additional cases of earthquakes induced by wastewater injection have been documented until 2009 4. A few sites regularly have larger quakes, such as the geysers geothermal plant in california which averaged two m4 events and 15 m3 events every year from 2004 to 2009. Here we identify the largest earthquake potentially related to injection, an m w 5. One mechanism by which injection related pore pressure increases can trigger seismic slip is well understood in the context of mohrcoulomb failure criteria e. The hydraulic fracturing practices usually trigger only tiny earthquakes or rather. Quantifying their contribution presents difficult challenges that will require new research into the physics of induced earthquakes and the potential for inducing largemagnitude events.
Earthquakes can be induced as part of the process to stimulate the production from tight shale. It has long been understood that earthquakes can be induced by impoundment of. In particular, the reporting of earthquake locations or hypocenters in real time helps provide an assessment of potential. Locating earthquakes constitutes a fundamental problem in seismology 1,2. Shaking from injectioninduced earthquakes in the central and.
Pdf the effect of varying fluid injection activities on. In oklahoma, which has the most induced earthquakes in us, only 12% of the earthquakes can be linked to hydraulic fracturing operations. Hydromechanical and frictional faulting behavior of fluidinjection. Zoback department of geophysics, stanford university, 397 panama mall, stanford, california 94305, usa abstract. Managing injection rates may be a useful tool to minimize the likelihood of induced earthquakes. A critical issue in seismology is to understand the relationship between earthquakes on various scales, giving the similarities and differences between the large earthquakes that occur on plate boundaries through to the very small shallow events associated with mining. Pdf maximum magnitude of injectioninduced earthquakes. This report is developed by the statesfirst induced seismicity by injection work. Pdf managing injectioninduced seismic risks researchgate. Minimizing and managing potential impacts of injectioninduced. Short note earthquake hazards programsouthern california. Induced seismicity refers to typically minor earthquakes and tremors that are caused by human. After dividing northcentral oklahoma into six study areas, we invert earthquake focal plane mechanisms in each area to constrain the orientation and relative magnitude of the principal stresses. Brown and shemin ge department of geological sciences, university of colorado, ucb 399, boulder, colorado.
Induced seismicity can also be caused by the injection of carbon dioxide as the storage step of carbon capture and storage, which aims to sequester. Link between larger volumes and induced earthquakes, but the problem is complex. Injectioninduced seismicity from class ii disposal wells. Hydraulic fracturing a gas and petroleum recovery process that uses fluid injection to open fissures in rock to allow trapped gas or crude oil to flow through a pipe to a wellhead at the surfacewas also shown to cause earthquakes and was found to be the primary cause of induced earthquakes in british columbia and western alberta as well. After dividing northcentral oklahoma into six study areas, we invert earthquake focal plane mechanisms in each area to constrain the orientation and. Earthquakes induced by deep injection there has been a growing realization that the principal seismic hazard from injectioninduced earthquakes comes from those associated with disposal of wastewater into deep strata or basement formations 5.
Injection induced earthquakes pose a serious seismic hazard but also offer an opportunity to gain insight into earthquake physics. Ellsworth earthquakes in unusual locations have become an important topic of discussion in both north america and europe, owing to the concern that industrial activity could cause damaging earthquakes. Modeling injectioninduced seismicity with the physicsbased. Injectioninduced seismicity and faultslip potential in the. It has long been understood that earthquakes can be induced by impoundment of reservoirs, surface and underground mining, withdrawal of fluids and gas from the subsurface, and injection of fluids into underground formations. We conclude that most faults in the system are highly sensitive to reactivation, and we postulate that many faults are still unidentified. Most seismic events triggered or induced by human activity produce only very lowlevel shaking. How large are the earthquakes induced by fluid injection. Injection induced earthquakes, such as those that struck in 2011, clearly contribute to the seismic hazard.
It has long been known that impoundmen t of reservoirs. The total induced earthquake energy is seen in table 1 to be 10% or less of the water injection energy for all the studied sites. A total of 18,160 m3 of fresh water was pumped into crystalline rocks over 49 days in june to july 2018. Even if the discrimination for natural versus anthropogenic seismicity is not always straightforward dahm et al. Injectioninduced earthquakes have, in particular, become a focus of discussion as the application of hydraulic fracturing to tight shale formations is enabling the production of oil and gas from previously unproductive formations. With increasing fluid pressure, the initial time for shear stress drop decreases, both the stress drop and the area of secondary damage increase, and the probability of unstable slip increases in a homogeneous rock matrix. The primary cause of these earthquakes, which can reach magnitude 3. In this study i consider the ground motions generated by 11 moderate mw4. The cumulative seismic moment is a robust measure of the earthquake response to fluid injection for injection volumes ranging from 3100 to about 12 million m3. Short note shaking from injection induced earthquakes in the central and eastern united states by susan e.
It occurred in a sequence, with 2 earthquakes of m w 5. We show that nearrealtime seismic monitoring of fluid injection allowed control of induced earthquakes during the stimulation of a 6. Not all wastewater injection wells induce earthquakes. National research council 20, committee on induced seismicity potential in energy technologies. By this definition, there can be triggered induced earthquakes. It has long been understood that earthquakes can be induced by impoundment of reservoirs, surface and underground mining, withdrawal of fluids and gas from the subsurface, and injection of fluids into. Plain language summary studies of the triggering mechanisms of injection. Highrate injection is associated with the increase in u. Earthquakes induced by deep injection there has been a growing realization that the principal seismic hazard from injection induced earthquakes comes from those associated with disposal of wastewater into deep strata or basement formations 5. Injection tends to cause a greater number of events, including damaging earthquakes. Sep 23, 2016 shaking from injection induced earthquakes in the central and eastern united states. Induced seismicity f rom oil and gas wastewater injection.