Oiland Gas Activities and Earthquakes
Oiland Gas Activities and Earthquakes
Naturalcalamities have been on the rise in the recent times in the UnitedStates. Indeed, it has been noted that the modern day United Stateshas experienced more natural calamities such as wild fires,earthquakes and tornadoes and hurricanes among others. Of course, ithas been well acknowledged that these natural calamities can never beprevented and in some instances, particularly the case ofearthquakes, they are unpredictable. This makes them all the moredangerous because there is no telling where they might strike next,their magnitude and even the level of destruction that they maycause. However, scientists have been studying the trends pertainingto the occurrence of earthquakes in the recent times with the aim ofcoming up with a clear and effective ways of predicting where theyoccur next, as well as their epicenters, causes and magnitudes. Astudy and analysis of the trends has allowed for the determination ofthe fact that there is a connection between the occurrence ofearthquakes and human activities particularly with regard to oil andgas exploration.
Alarge proportion of oil drilling activities are done using frackingor hydraulic fracturing where natural gas would be extracted from theshale rock layers in the depths of the earth. Fracking is arelatively new technology that allows for the production of naturalgas in shale that was previously unreachable using conventionalmeans. Nevertheless, recent drilling technology advancements haveresulted in the emergence of new man-made or artificial hydraulicfractures in the shale plays that previously were not available forexploration1.In this technique, horizontal veins are created off the verticalwells after which pressurized water mixed with sand and otheradditives ism pumped in the horizontal wells. Scholars andresearchers have noted that the energy that is released during thisfracking process may result in seismic activity2.Nevertheless, they insinuate that such seismic activity is so lowthat rarely is it felt on the surface. It occurs in the process ofbeing fracturing the rocks situated around 3000 meters below thesurface.
Moreoften than not, microseismic events in the course of hydraulicfracturing are usually less than magnitude minus three (-3) or evenminus two (-2) as measured on the Richter scale. Indeed, studies doneon hydraulic fracturing related seismic activity in the UnitedKingdom showed that the blend of geological factors that are requiredso as to generate a seismic activity that has a higher than normalreading on the Richter scale may not be so frequent, in which case alarge number of such events are limited to approximately magnitude 3earthquakes as measured on the Richter scale3.This is seen as the worst case scenario. This has made a large numberof oil drilling companies to be quick to defend themselves from anyblame in instances where there is an increase in the number andmagnitude of seismic activity after they have started their oildrilling or rather hydraulic fracturing activities4.They have always stated that fracking alone would never cause achange in the seismic activities in an area, rather, there would haveto be the wastewater disposal in deep wells. While there may be sometruth in this assertion, it is worth noting that fracking does notsimply involve drilling horizontal holes on the shale rock where thenatural gas and oil is being held rather it would still have theinjection of water and sand combined with some other toxic chemicals.This means that there would never be fracking without the water.
Onthe same note, the simple act of drilling vertical holes so as toreach the shale rock and horizontal holes so as to allow the gastrapped in the shale rock to escape to the pipes and the tanks wouldweaken the rocks and increase the probability that the tectonicswould move persistently5.This becomes even more likely in instances where the holes have beendug or rather the oil exploration has been done in areas where therewere already existing fractures on the shale rock6.
Frackingand the Liberation of Methane
Oneof the most fundamental details pertaining to the relationshipbetween earthquakes and frackingtechnology underlines the fact thatin a large number of instances, it is not the actual drilling thatresults in underground destabilization, rather it is the process ofunderground waste chemicals disposal. Fracking technologynecessitates that the minors drill deep into the shale deposits,after which they are to inject millions of gallons of lubricatingchemicals in the underground7.The chemicals are referred to as fracking fluids, and their injectionresults in high pressure that would result in the rock formationsslipping against each other, thereby freeing up the methane andnatural gas deposits between the rocks. In ideal situations, thefreed up methane gas would flow directly into the pipelines andstorage tanks, after which they are taken to business premises andhomes of citizens. Once the injection process has been completed, alarge number of the lubricating chemicals would be recaptured as“wastewater”. Scholars have noted that the problem lies in thisstuff, particularly considering that there exists tens of millions ofgallons of wastewater that requires to be disposed8.Of particular note is the fact that wastewater does not resemble theactual water, rather it is a toxic concoction of the originalhazardous material that had been sent underground so as to fractureor break up the rocks that contained the gas, coupled with thecontaminants that it absorbed in the course of fracturing or frackingthe rocks9.Apart from states such as Pennsylvania, where it is possible tolegally dump this waste water into rivers, waste fracking fluids are,more often than not, re-injected into the deep wells that had beendrilled for the sole purpose of permanent storage. It goes withoutsaying that there exists an ever increasing number of these wells asthe speed of drilling grows into a global frenzy10.Subject to the geologic conditions, as well as the competencypertaining to the disposal company, there is a high possibility thatthe wastewater would migrate in considerably unpredictable ways11.On the same note, scholars have underlined the possibility that theremay arise the unintended consequences of lubricating the faultinterfaces in the underground. Indeed, it has been acknowledged thatthe additional lubrication would case the movement of the rock andgenerate tremors of different magnitudes and intensities. Ofparticular note is the fact that a large number of swarm tremors areminute but occur quite frequently, with more than a dozen tremorsoccurring on a daily basis over long periods of time in someinstances. Irrespective of the magnitudes and durations of injectionwell related earthquakes, research shows that there is an increase inswarms as a result of the increase in the drilling activities of oilextracting companies. For instance, places such as Youngstown, Ohio,which is located on the western end of the Marcellus Shale, had neverexperienced any earthquake prior to the occurrence of those that wereinduced by the fracking wastewater injection wells. This resulted inthe shutting down of all the injection wells that the D&L EnergyCompany had dug in the area by the Ohio Oil & Gas Commission. Ofparticular note is the fact that one of the D & L wells was closeto the epicenter pertaining to a number of earthquakes that occurredin Youngstown area in 2011.
Thesereports should not have been surprising considering that similareffects have been noted even without the drilling or oil extractionprocesses. Indeed, scientists fist found the link between theunderground disposal of waste water and artificial or inducedearthquakes in Colorado more than 5 decades ago when the waste waterinjections done on the Rocky Mountain Arsenal resulted in localearthquake swarms. Indeed, the army had, in 1961 decided that toxicwaste water was best disposed off from the napalm production viadrilling a 12,000 foot well within the rocky mountains, after whichthe wastewater would be injected into the earth’s crust.Researchers have noted that the army injected a total of 165 milliongallons of toxic waste water into the so drilled wells from 1962 toaround 196612.It was not long before the injected waste water resulted in numerousearthquakes in the region, thereby forcing the army to shut down theoperation. A similar example may be seen in the Arkansas tremors thatoccurred in 2010 and 2011, referred to as The Guy. The earthquakeswarms that had been induced by the waste water disposal surprisedthe residents. However, it is noted that the area had since 2008 beenexperiencing a classic gas drilling frenzy. As much as the place hadin the previous times experienced a number of earthquakes, theheightened frequency of the same in 2010 was particularly phenomenal,with researchers noting that it was normal to have a dozen quakes perdiem. This resulted in the eventual shutting down of the four wellsthat were within the area, with the Arkansas Oil and Gas Commissionimposing a suspension on new wells. Similar events were recorded inBraxton County WV, which was home to freak earthquakes in 2010. It isfurther noted that a nearby well had had 10.6 million gallons ofwastewater brine emanating from the Marcellus Shale sites, injectedinto the wells beginning around June 2009. This caused the locals to,rightly, suspect that there was a “cause and effect” relationshipbetween the two. Eventually, disposal companies were compelled by theWest Virginia Oil and Gas Commission to reduce the rates and pressureof salt water injection to the well’s bedrock. This resulted to asignificant reduction of the frequency and magnitudes of theaccidents in the area.
Asmuch as the earthquakes resulting from the simple drilling may not bestrong enough to be felt or, in some cases, to be registered in theRichter scale, the same cannot be said of those that involve thedisposal of millions of gallons of wastewater in the wells. Indeed,reports issued in 2012 by the United States geological surveyindicated that a large number of earthquakes actually registered andfelt were close to active injection wells. Geophysicists noted thatthere was a high plausibility that the high water pressure that, moreoften than not, was utilized in the wastewater injections had thecapacity to nudge the previously dormant faults beyond theirconsiderably “locked” states. Similar conclusions were made byscientists in Columbia university who studied the extremely rare 4.0earthquake that occurred in 2011 in Ohio, as was the case forArkansas in the same year where a 4.7 magnitude earthquake occurredthereby prompting the shutting down of injection wells particularlythose that were close to the faults. The Ohio scientists noted thatas the pressurized water found its way into the cracks deep below theground, it would have the capacity to result in earthquakes along theancient fault lines. Of particular note is the fact that Ohio washome to more than 177 disposal wells. These included the Youngstownwell which was located in a considerably seismically dormant regionthat bordered Pennsylvania. Even more telling is the fact that theinitial quakes came up in March, a few months following the beginningof the fracking wastewater injection from Pennsylvania. Later on,there were around 9 other minute tremors, which forced the Ohioauthorities to institute monitoring in the area using mobileinstruments that had the capacity to offer a considerably moreaccurate locations pertaining to the subsequent earth tremors. It isworth noting that on 24thDecember, the instruments used in monitoring the earthquakes hadrecorded an earth tremor of 2.7 magnitude situated 2.2 miles underthe surface, half a mile away, as well as around 2000 feet under the1.7 mile deep well. The accurate measurement of the source of seismicactivity provided sufficient proof pertaining to the existence of alink between the wastewater disposal wells and the occurrence ofearthquakes. On the same note, instruments in Lamont also located the4.0 magnitude 31stDecember earthquake approximately 300 feet east, as well as some 500feet below the previous event. Of particular note is the fact that a4.0 magnitude earthquake comes as around 40 times more powerfulcompared to the one of 2.7 magnitude. This forced the authorities toshutdown and suspend any activity in the four wells that had been dugwithin a 5 mile radius.
Inthe course of shutting down the wells, scientists noted thathydrofracking, by its very nature, results in tiny earthquakes simplybecause it revolves around the fracturing of a rock. Theseearthquakes, however, may be largely imperceptible since the processoccurs in considerably weak and shallow shales that crack and formfractures prior to the building up of must pressure and strain.However, quakes that emanate from or triggered by injection wells ofwaste water may be potentially more powerful, simply because muchmore fluid is, more often than not, being pumped or injectedunderground at the location for a longer period of time. In instanceswhere the fluid gets into a pre-existing fault, it may have thecapacity to exert pressure on the rocks sufficient to move the rock.Scientists have acknowledged that the more pressure that is exertedon the rock formation, the higher the magnitude of the earthquakes.This comes out clearly given the 40-times difference between themagnitude registered in one of the wells in Ohio on 24thNovember and the one registered on 24thDecember. In essence, it becomes imperative that once a tremor hasbeen recorded in a particular area where injection wells are located,the injection operations should stop immediately as the profitsderived from the gas may not be sufficient to cover the damage thatwill take place if the injection continues.
MassiveExtraction of Ground Water
Inaddition, it is noted that earthquakes may occur as a result of theimmense volumes of groundwater that are extracted in the course ofdrilling for oil and gas. Scholars have underlined the fact thatthree of the biggest seismic activities induced by human activity inhistory took place close to the Gazli natural gas-field inUzbekistan, Russia in 1976, one of which was a 7.3 magnitudeearthquake13.Russian scientists later on confirmed that the combination ofinjection and extraction of fluid may have altered or modified thetectonic action in the area, thereby causing the quake14.Of particular note is the fact that the Gazil region had neverexperienced earthquakes prior to the 1956 discovery of gas field inthis region. A similar scenario played out in 2011 in Lorca, Spain,where a killer quake attributed to the prolonged and deep extractionof underground water occurred. A multinational study undertaken byNature Geoscience determined that there had been a considerable andpersistent increase in the depth of the wells dug within the previous50 years, which resulted in the sucking up of even more volumes ofwater in the region15.This resulted in a drop of the water table by around 275 verticalyards throughout the years. Scholars noted that the decades longactivity may have resulted in the weakening of the underground basinclose to an already existing fault line, thereby stimulating theoccurrence of the catastrophic event16.
Thiswas also the case for the Newcastle quake that occurred in January2006. Scholars have underlined the notion that the removal of themillions of barrels of oil may result in too much stress therebytriggering a quake17.However, even more significant was the pumping of groundwater that isalways necessary in averting the possibility for flooding in themines. It is noted that for every ton of coal or fossil fuels thatare obtained, it becomes necessary that about 4.3 times of water tobe extracted or sucked out. It is noted that the extraction of waterduring mining would result in an enormous change in the mass, whicheventually refigures the stresses of an earthquake on an area, moreoften than no increasing the possibility for its occurrence.
Burbidge,D. The 2012 Australian Earthquake Hazard Map. GeoscienceAustralia,Record, 2012/71.
Davies,R., Foulger, G., Bindley, A. and Styles, P., 2013. Induced Seismicityand Hydraulic Fracturing for the Recovery of Hydrocarbons. Marineand Petroleum Geology,45, 171-185.
Ellsworth,W.L., Hickman, S.H., Lleons, A.L., McGarr, A., Michael, A.J., andRubenstein, J.L., 2012. Are elasticity rate changes in themidcontinent natural or manmade? SeismologicalSociety of America, Abstract,12-137.
Rutledge,James T and Phillips, W. Scott, 2003. Hydraulic stimulation ofnatural fractures as revealed by induced microearthquakes, CarthageCotton Valley gas field, east Texas. Geophysics,68(2), 441 – 452.
Shapiro,S.A., C. Dinske, and J. Kummerow, 2007, Probability of agiven-magnitude earthquake induced by a fluid injection, Geophys.Res.Lett., 34.
Shemeta,Julie and Anderson, Paul, 2010. It`s a matter of size: Magnitude andmoment estimates for microseismic data. TheLeading Edge,March, 296-302.
Šilneý,Jan, Hill, David P., Eisner, Leo and Cornet, Francois H., 2009.Non-double couple mechanism of microearthquakes induced by hydraulicfracture. Journalof Geophysical Research,114(B08)
Vallejos,J.A., McKinnon, S.D., 2011. Correlations between mining andseismicity for reentry protocol development. InternationalJournal of Rock Mechanics and Mining Sciences48, 616-625.
VanEck, T., Goutbeek, F., Haak, H., Dost, B., 2006. Seismic hazard dueto small-magnitude shallow-source, induce earthquakes in TheNetherlands. EngineeringGeology87, 105-121.
WangQingyun, Zhang Qiuwen and Li Feng.(2003).Study on risk of inducedearthquake in reservoir head region of Three Gorges projection onYangtze River. Journalof Geodesy and Geodynamics23:2,101-106.
1 Šilneý, Jan, Hill, David P., Eisner, Leo and Cornet, Francois H., 2009. Non-double couple mechanism of microearthquakes induced by hydraulic fracture. Journal of Geophysical Research, 114(B08)
2 Šilneý, Jan, Hill, David P., Eisner, Leo and Cornet, Francois H., 2009. Non-double couple mechanism of microearthquakes induced by hydraulic fracture. Journal of Geophysical Research, 114(B08)
3 Vallejos, J.A., McKinnon, S.D., 2011. Correlations between mining and seismicity for reentry protocol development. International Journal of Rock Mechanics and Mining Sciences 48, 616-625.
4 Šilneý, Jan, Hill, David P., Eisner, Leo and Cornet, Francois H., 2009. Non-double couple mechanism of microearthquakes induced by hydraulic fracture. Journal of Geophysical Research, 114(B08)
5 Davies, R., Foulger, G., Bindley, A. and Styles, P., 2013. Induced Seismicity and Hydraulic Fracturing for the Recovery of Hydrocarbons. Marine and Petroleum Geology, 45, 171-185.
6 Wang Qingyun, Zhang Qiuwen and Li Feng.(2003).Study on risk of induced earthquake in reservoir head region of Three Gorges projection on Yangtze River. Journal of Geodesy and Geodynamics 23:2,101-106.
7 Vallejos, J.A., McKinnon, S.D., 2011. Correlations between mining and seismicity for reentry protocol development. International Journal of Rock Mechanics and Mining Sciences 48, 616-625.
8 Davies, R., Foulger, G., Bindley, A. and Styles, P., 2013. Induced Seismicity and Hydraulic Fracturing for the Recovery of Hydrocarbons. Marine and Petroleum Geology, 45, 171-185.
9 Van Eck, T., Goutbeek, F., Haak, H., Dost, B., 2006. Seismic hazard due to small-magnitude shallow-source, induce earthquakes in The Netherlands. Engineering Geology 87, 105-121.
10 Van Eck, T., Goutbeek, F., Haak, H., Dost, B., 2006. Seismic hazard due to small-magnitude shallow-source, induce earthquakes in The Netherlands. Engineering Geology 87, 105-121.
11 Shapiro, S.A., C. Dinske, and J. Kummerow, 2007, Probability of a given-magnitude earthquake induced by a fluid injection, Geophys. Res. Lett., 34.
12 Burbidge, D. The 2012 Australian Earthquake Hazard Map. Geoscience Australia, Record, 2012/71.
13 Shemeta, Julie and Anderson, Paul, 2010. It`s a matter of size: Magnitude and moment estimates for microseismic data. The Leading Edge, March, 296-302.
14 Ellsworth, W.L., Hickman, S.H., Lleons, A.L., McGarr, A., Michael, A.J., and Rubenstein, J.L., 2012. Are elasticity rate changes in the midcontinent natural or manmade? Seismological Society of America, Abstract, 12-137
15 Rutledge, James T and Phillips, W. Scott, 2003. Hydraulic stimulation of natural fractures as revealed by induced microearthquakes, Carthage Cotton Valley gas field, east Texas. Geophysics, 68(2), 441 – 452.
16 Ellsworth, W.L., Hickman, S.H., Lleons, A.L., McGarr, A., Michael, A.J., and Rubenstein, J.L., 2012. Are elasticity rate changes in the midcontinent natural or manmade? Seismological Society of America, Abstract, 12-137
17 Burbidge, D. The 2012 Australian Earthquake Hazard Map. Geoscience Australia, Record, 2012/71.