Seismicity induced refers to earthquakes and small earthquakes caused by human activity that alter pressure and pressure on the Earth's crust. Most of the induced seismicities have low magnitudes. Some sites regularly have larger earthquakes, such as the Geyser geyster plant in California that average two M4 and 15 M3 events each year from 2004 to 2009.
The ongoing multi-year research on earthquakes induced by the US Geological Survey (USGS) published in 2015 shows that most significant earthquakes in Oklahoma, such as the 1952 5.7 El Reno earthquake may have been caused by deep waste injection. water by the oil industry. "The level of the earthquake has increased markedly in several areas in Central and Eastern America (CEUS), especially since 2010, and scientific research has linked most of this increased activity to wastewater injection at deep wells."
Induced seismicity can also be caused by carbon dioxide injection as a storage step for carbon capture and storage, which aims to absorb carbon dioxide derived from the production of fossil fuels or other sources in the Earth's crust as a means of mitigating climate change. This effect has been observed in Oklahoma and Saskatchewan. Although safe practices and existing technologies can be utilized to reduce the risk of seismicity caused by carbon dioxide injection, the risk is still significant if storage is large. The consequences of induced seismicity may disrupt pre-existing errors in the earth's crust and compromise the seal integrity of the storage location.
The seismic dangers of induced seismicity can be assessed using the same technique as for natural seismicity, although taking into account non-stationary seismicity. It seems that earthquakes that shake from an induced earthquake are similar to those occurring in natural tectonic earthquakes, although differences in depth need to be taken into account. This means that the ground motion model is derived from natural earthquake recording, which is often more in a strong motion database than data from an induced earthquake, can be used. Furthermore, risk assessment can be undertaken, taking into account the seismic hazards and vulnerabilities of exposed elements at risk (eg local population and building stock). Finally, risks can, at least theoretically, be mitigated, either through modification of hazards or the reduction of exposure or vulnerability.
Video Induced seismicity
Cause
There are many ways in which induced seismicity has been seen to occur. In recent years, some energy technologies that inject or extract fluids from Earth, such as oil and gas extraction and geothermal energy development, have been found or suspected to cause seismic events. Some energy technologies also produce waste that can be managed through disposal or storage by injecting deep into the soil. For example, waste water from oil and gas and carbon dioxide production from various industrial processes can be managed through underground injection.
Artificial Lake
Columns of water in large artificial lakes and deeply alter in-situ stress throughout errors or fractures. In this reservoir, the weight of the water column can significantly change the pressure on the underlying fault or fracture by increasing the total stress through direct loading, or decreasing the effective stress through increased pore water pressures. This significant stress change can cause sudden movement along the fracture or fracture, resulting in an earthquake. Reservoir-induced seismic events can be relatively large compared to other forms of induced seismicity. Although the understanding of seismic activity induced by the reservoir is very limited, it has been noted that seismicity appears to occur at dams more than 330 feet (100 m). The extra water pressure created by the large reservoir is the most accepted explanation for seismic activity. When the reservoir is filled or dried, induction seismicity can occur immediately or with small time lags.
The first case of reservoir-induced earthquake occurred in 1932 in the Aljazair Oued Fodda Dam.
The magnitude 6.3 magnitude earthquake of 1967 Koynanagar takes place in Maharashtra, India with its epicenter, fore and afters all situated near or under the Koyna Dam dam. 180 people died and 1,500 were injured. The effects of the quake were felt 140 miles (230 km) in Bombay with tremors and power cuts.
During the beginning of the Vajont Dam in Italy, there were seismic shocks recorded during initial filling. After a landslide nearly filled the reservoir in 1963, causing a massive flood and about 2,000 deaths, it was drained and consequently seismic activity was virtually non-existent.
On August 1, 1975, a magnitude 6.1 earthquake in Oroville, California, was linked to the seismicity of a large earth-filled dam and recently constructed and filled reservoir.
The filling of Katse Dam in Lesotho, and Nurek Dam in Tajikistan is an example. In Zambia, Lake Kariba may provoke similar effects.
The 2008 Sichuan earthquake, which caused about 68,000 deaths, is another possible example. An article in Science suggests that the construction and filling of the Zipingpu Dam may have triggered an earthquake.
Some experts fear that the Three Gorges Dam in China could lead to an increase in the frequency and intensity of earthquakes.
Mine
The mine leaves a cavity that generally alters the balance of power within the rock, repeatedly causing bursts of rock. These voids can collapse resulting in seismic waves and in some cases reactivate existing errors that cause small earthquakes. The collapsed cave hole forming the exhaust hole will produce a very identical local seismic event .
Disposal of wells
Injecting liquids into waste disposal wells, most often in disposing of water produced from oil and natural gas wells, have been known to cause earthquakes. This high salt water is usually pumped into a saltwater drain well (SWD). An increase in pore pressure below the surface may trigger movement along the fault, resulting in an earthquake.
One of the first known examples is from Rocky Mountain Arsenal, northeast of Denver. In 1961, waste water was injected into the inner layer, and this was later found to have caused a series of earthquakes.
The 2011 Oklahoma earthquake near Prague, measuring 5.8, occurred after 20 years injecting wastewater into a porous formation at increased pressure and saturation. On September 3, 2016, a stronger earthquake with a strength of 5.8 occurred near Pawnee, Oklahoma, followed by nine aftershocks between magnitude 2.6 and 3.6 within 3 1/2 hours. Tremors are felt as far as Memphis, Tennessee, and Gilbert, Arizona. Mary Fallin, Oklahoma's governor, declared a local emergency and closure order for a local sewage well ordered by the Oklahoma Corporation Commission. The ongoing multi-year research on earthquakes induced by the US Geological Survey (USGS) published in 2015 shows that most significant earthquakes in Oklahoma, such as the 5,55 El Reno earthquake in 1952 may have been caused by deep waste injection. water by the oil industry. However, before April 2015, the position of the Oklahoma Geological Survey was that the quake was most likely caused by natural causes and not triggered by injection of waste. This is one of the many earthquakes that have affected the Oklahoma region.
Since 2009 earthquakes have become hundreds of times more common in Oklahoma with a magnitude of 3 events increasing from 1 or 2 per year to 1 or 2 per day. On April 21, 2015, the Oklahoma Geological Survey released a statement that reversed its position in the earthquake caused in Oklahoma: "The OGS considers it highly likely that the majority of recent earthquakes, particularly in central and north-central Oklahoma, are triggered by water injection produced in a disposal well. "
Hydrocarbon Extraction and Storage
Large scale fossil fuel extraction can produce earthquakes. Induced seismicity may also be associated with underground gas storage operations. Seismic sequence September-October 2013 occurs 21 km off the Gulf coast of Valencia (Spain) is probably the most induced seismicity case associated with underground gas storage operations (Project Castor). In September 2013, after injection surgery began, the Spanish seismic network noted a sudden increase of seismic. Over 1,000 events with magnitude ( M L ) between 0.7 and 4.3 (the largest earthquake ever associated with operations gas storage) and located near the injection platform carrying about 40 days. Due to significant population concerns, the Spanish Government suspended operations. By the end of 2014, the Spanish government definitively ends the UGS plant concession. Since January 2015 about 20 people who took part in the transaction and approval of the Castor Project were charged.
Groundwater extraction
Changes in crust stress patterns caused by large groundwater extraction have been shown to trigger earthquakes, as in the case of the 2011 Lorca earthquake.
Geothermal energy
Improved geothermal systems (EGS), a new type of geothermal power technology that does not require natural convective hydrothermal resources, is known to be associated with induction seismicity. EGS involves pumping fluid under pressure to increase or create permeability through the use of hydraulic fracturing techniques. Hot dry rock (HDR) EGS actively creates geothermal resources through hydraulic stimulation. Depending on the nature of the rock, and at the pressure of the injection and fluid volume, the reservoir rock can respond with tensile failure, as is common in the oil and gas industry, or with the shear failure of the existing rock joint set, which is considered the main mechanism of reservoir growth in effort EGS.
The HDR and EGS systems are currently being developed and tested at Soultz-sous-ForÃÆ'ªts (France), Desert Peak and Geysers (USA), Landau (Germany), as well as Paralana and Cooper Basin (Australia). The induced seismicity occurrence in Geyser geothermal field in California has been highly correlated with injection data. The test site in Basel, Switzerland, has been closed due to seismic events induced. In November 2017, Mw 5.5 hit the city of Pohang (South Korea) injured several people and caused widespread damage, seismic seismic proximity to the EGS site, where stimulation operations had occurred several months before the earthquake increased the likelihood that the earthquake anthropogenic. According to two different studies it seems plausible that the Pohang earthquake was induced by EGS surgery.
Researchers at MIT believe that the seismicity associated with hydraulic stimulation can be reduced and controlled through siting and other techniques. With appropriate management, the number and magnitude of induced seismic events can be reduced, significantly reducing the likelihood of destructive seismic events.
Induction of seismicity in Basel caused the suspension of its HDR project. Seismic hazard evaluation was then carried out, resulting in the cancellation of the project in December 2009.
Hydraulic breakage
Hydraulic breaking is a technique in which high pressure liquids are injected into low permeable reservoir rocks to induce fractures to increase hydrocarbon production. This process is generally associated with seismic events that are too small to feel on the surface (with the magnitude of moments ranging from -3 to 1), although larger larger events are not excluded. For example, several cases of large-scale events (M & g4; 4) have been recorded in Canada in the unconventional resources of Alberta and British Columbia.
Carbon Capture and Storage
Important of risk analysis for CCS
Technological operations involving long-term geologic storage of waste fluids have been shown to induce seismic activity in the surrounding area, and the correlation of minimum seismic dormancy periods in injection and pressure volumes has even been shown for injection of fracking wastewater in Youngstown, Ohio. Particular attention to the viability of carbon dioxide storage from coal-fired power plants and similar enterprises is that the scale of the intended CCS project is much greater at both the injection rate and the total volume of injections than the current or previous operations that have been proven to induce seismicity. Thus, extensive modeling should be done from future injection sites to assess the potential risks of CCS surgery, particularly in relation to long-term carbon dioxide storage effects on shale limestone integrity, since potential leakage of liquid to the surface may be high enough for moderate earthquakes. However, the potential of CCS to induce large earthquakes and CO 2 leaks remains a controversial issue.
Monitoring
Because geological carbon dioxide sequestration has the potential to induce seismicity, researchers have developed methods to monitor and model the risk of seismic induced injury, to better manage the risks associated with this phenomenon. Monitoring can be done by measuring from instruments such as geophones to measure the movement of the soil. Generally the instrument network around the injection site is used, although many carbon dioxide injection sites do not currently use monitoring devices. Modeling is an important technique for assessing the potential of induced seismicity, and there are two main types of models used: physical and numerical. The physical model uses measurements from the early stages of the project to estimate how the project will behave once again injected carbon dioxide, and numerical models use numerical methods to simulate the physics of what goes on in the reservoir. Both modeling and monitoring are useful tools for measuring, and thus better understanding and reducing risks associated with injection-induced seismicity.
Mechanism of failure due to fluid injection
To assess the risk of induced seismicity associated with carbon storage, one must understand the mechanism behind rock failure. The Mohr-Coulomb failure criterion describes the shear failure in the fault field. Generally, failure will occur in the existing error due to several mechanisms: increased shear stress, decreased normal pressure or increased pore pressure. Supercritical CO2 injection will change the pressure in the reservoir as it expands, causing potential failure at the nearest error. The fluid injection also increases the pore pressure in the reservoir, triggering a slip on the plane of existing stone weakness. The latter is the most common cause of seismic induction due to fluid injection.
The criterion of Mohr-Coulomb's failure states that
dengan tegangan geser kritis yang menyebabkan kegagalan pada kesalahan, kekuatan kohesif sepanjang kesalahan, tegangan normal, koefisien gesekan pada bidang patahan dan tekanan pori dalam kesalahan. Ketika dicapai, kegagalan geser terjadi dan gempa bumi dapat dirasakan. Proses ini dapat direpresentasikan secara grafis pada lingkaran Mohr.
Perbandingan risiko karena CCS dibandingkan metode injeksi lainnya
Although there is an induced seismic risk associated with large-scale carbon sequestration and underground storage, there is now a much more serious risk than other injections. Wastewater injection, hydraulic fracturing, and secondary recovery after oil extraction all contribute more to seismic events induced than carbon capture and storage in recent years. There is actually no major seismic event associated with carbon injection at this point, whereas there are recorded seismic events caused by other injection methods. One example is the massive increase of induced seismicity in Oklahoma, USA caused by large volumes of wastewater into Arbuckle Group sediments.
Maps Induced seismicity
Nuclear Activity
Nuclear activity can cause seismic activity, but according to the USGS, seismic activity is less energetic than the original nuclear explosion, and generally does not produce an earthquake/aftershock of a reasonable size. In fact, they instead release the elastic strain energy stored in the rock, which is recycled into a shock wave of the initial explosion, increasing the power output.
AS. National Research Council report
The 2012 report from the US National Research Council examines the potential of energy technologies - including shale gas recovery, carbon capture and storage, geothermal energy production, and the development of conventional oil and gas - to cause earthquakes. The report found that only a fraction of the injection and extraction activities among hundreds of thousands of energy development sites in the United States have induced seismicity at a level seen by the public. However, although scientists understand the general mechanisms that induce seismic events, they can not accurately predict the magnitude or occurrence of this earthquake because of inadequate information about natural rock systems and the lack of predictive models validated at specific energy development sites.
The report notes that hydraulic fracturing has a low risk to induce earthquakes that can be felt by people, but underground injection from waste water generated by hydraulic fracturing and other energy technologies poses a higher risk of causing the earthquake. In addition, carbon capture and storage - a technology for storing excess carbon dioxide underground - may have the potential to induce seismic events, since significant fluid volumes are injected underground for long periods of time.
References
Further reading
- Kisslinger, C (1976). "Overview of the theory of induced seismic mechanisms". Geological Engineering . 10 (2-4): 85-98. doi: 10.1016/0013-7952 (76) 90014-4. ISSN 0013-7952.
- Talwani, P. (1997). "About the Nature of Reservoir-Induced Seismicity". Pure and Applied Geophysics . 150 (3-4): 473-492. Bibcode: 1997PApGe.150..473T. doi: 10.1007/s000240050089. ISSNÃ, 0033-4553.
External links
- Map of the reservoir-induced earthquake on the International River
- WEBINAR: Yes, Human Really Causes Earthquakes - IRIS Consortium
- One-year seismic hazard forecast for Central and Eastern America from natural and induced earthquakes - United States Geological Survey, 2016 (with map)
- Induction Earthquake - US Geological Survey Site
Source of the article : Wikipedia
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