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U.S. mid-continent earthquakes linked to high-rate injection wells
June 18, 2015听听听听听听听听听听听听听 听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听 Matthew Weingarten
Fluid injection wells used in oil and gas development are the cause of a dramatic increase in earthquakes in the central and eastern U.S. since 2009, including several damaging quakes ranging between magnitudes 4.7 and 5.6 in Colorado, Oklahoma, Texas and Arkansas, says a new study by the 暗网禁区 and the U.S. Geological Survey.
According to CU-Boulder doctoral student Matthew Weingarten, who led the study, the number of earthquakes associated with injection wells has skyrocketed from a handful per year in the 1970s to more than 600 in 2014.
CUT 1 鈥淲e put together a database from state-by-state of 180,000 wells and we compared that to where the timing and location of earthquakes in the central and eastern United States. And what we found was that the entire increase in the number of earthquakes in the last five years can be associated with injection wells. (:19) That number of earthquakes has subsequently increased up to 650 earthquakes last year in the region.鈥� (:27)
Weingarten says it鈥檚 important to note the study shows that not all injections wells are associated with earthquakes. He says it鈥檚 only the 鈥渉igh-rate鈥� injection wells - those pumping more than 300,000 barrels of wastewater a month into the ground - that鈥檚 causing the earthquakes.
CUT 2 鈥淲e compared wells by injection rate. The total volume that they put into the well, their injection pressure and their injection depth and what we found was only injection rate 鈥� the maximum injection rate of a given well 鈥� was correlated to the increase likelihood of earthquakes. (:17) So the very highest rate wells - wells that have been injecting 300,00 barrels per month or more - are one-and-a-half to two times as likely to be near an earthquake than wells that are injecting at lower rates.鈥� (:30)
What鈥檚 important about the findings of this study, says Weingarten, is that the may help regulatory agencies overseeing oil and gas production to easily set standards to eliminate these induced earthquakes.
CUT 3 鈥淭his is really important result because it is an easy perimeter for regulatory agencies and other research bodies to look at and say, 鈥楾his is a perimeter that we can control. And if we can control this perimeter than we can control the likelihood of an induced earthquake.鈥� 鈥� (:20)
The team noted that thousands of injection wells have operated during the last few decades in the central and eastern U.S. without a ramp-up in seismic events. It鈥檚 only the introduction of new wells with high injection rates that have created the problem, says Weingarten.
CUT 4 鈥淭ens of thousands of injection wells have operated without induced earthquakes for several decades. (:06) And the important piece to this is that new production methods that produce much, much larger volumes of waste water that need to be disposed of are subsequently producing high-rate injection wells that are associated with the recent increase in seismicity.鈥� (:21)
In Colorado, the areas most affected by earthquakes associated with injection wells were the Raton Basin in the southern part of the state and near Greeley north of Denver.
A video news story on the study is available at .
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