Swarms of Earthquakes Shake Up Shale Gas Fields
Do tremors plaguing industry in Texas, Holland, and beyond offer a glimpse of BC's future?
By Andrew Nikiforuk, 31 Jan 2014, TheTyee.ca
http://thetyee.ca/News/2014/01/31/Shale ... rthquakes/
Pumping these wastes permanently underground remains a big and uncertain business. Texas operates more 50,000 injection wells, five of which are located near Azle, the state's new earthquake centre.
Alberta has nearly 2,000 injection well sites and Oklahoma, which experienced a record 2,600 quakes last year, is home to 5,000 injection sites. As of 2007, B.C. employed more than 100 wastewater wells in its gas fields.
Many of continent's more than 680,000 injection and disposal wells have sprung leaks or have fractured into aquifers.
Since the advent of hydraulic fracturing of shale gas plays in northern B.C., the volume of water disposed by the industry through deep injection wells has grown from approximately 1.2 billion litres in 1990 to 4.2 billion litres in 2009 -- an average increase of seven per cent per year.
Geologists have known for years that various forms of hydrocarbon production, from drilling and pumping to injecting and fracturing, can cause man-made earthquakes. Experts call the phenomenon "induced seismicity."
One 2013 study found that large earthquakes in Japan and Chile were now unsettling injection waste disposal sites in Oklahoma, Texas and Colorado, creating smaller earthquakes.
"The remote triggering by big earthquakes is an indication the area is critically stressed," said author Nicholas van der Elst, a researcher at Columbia University's Lamont-Doherty Earth Observatory.
The natural gas industry sparked a swarm of major earthquakes in the 1970s and '80s in central Alberta. The rapid draining of a sour gas field near Rocky Mountain House triggered as many as 146 quakes in one year.
Oil sands waste disposal in Cold Lake, Alberta triggered earthquakes in the '60s and '80s.
The natural gas industry also shook up Gazli, Uzbekistan with earthquakes as high as 7.3 on the Richter scale in the '70s.
Russian scientists concluded that a series of major quakes were "the strongest of all the known earthquakes in the plain of Central Asia" and that "the amassed data indicate that the Gazli earthquakes were triggered by the exploitation of the gas field."
But the with the advent of multi-stage horizontal hydraulic fracturing, which injects large volumes of water and chemicals at extremely high pressures much deeper underground than ever before and produces enormous amounts of waste fluids, the industry has set off earthquakes with startling regularity.