Do you know that injecting liquid into the ground can cause a quake? Yup. Last Sunday Arkansas experienced its largest quake in 35 years, a magnitude 4.7 in Greenbrier. About 4 miles north east of the center of town. Northern Arkansas is home to the Fayetteville Shale formation which contains lots of natural gas, 7 trillion cubic feet, but is considered an unconventional field. To get this nat gas out, fracking is used. And everybody @ D-Kos just loves Fracking, doncha?
Consider this diary as a followup to Statusquomustgo's dairy on monday, Arkansas earthquakes due to fracking disposal?, which got me to thinking.....
Fracking is a process that uses fracking fluid, under pressure to force open cracks in the shale which release the nat gas. The fluid used has a bunch of things in it, corrosion inhibitors, Mineral oil, borate salts, hydrochloric acid, and grit, like silica and quartz known as Proppant.
Proppants consist of granular material, such as sand, which is mixed with the fracture fluid and is used to hold open the hydraulic fractures allowing the gas or oil to flow to the production well.
Fracking fluid also contains swell stuff like Anti freeze, well, lets be technical, ethelyne glycol, naphthalene, ammonium bisulfite.
SO when the the frackers are done with the fracking fluid, what do they do with it? Simple, they pump it into the ground. Run for the hills, the ground is a shaking.....
If you don't know it by now, injecting liquids a mile or 2 into the earth, does cause microquakes, mostly under magnitude 1.2 and anywhere from 18 hours after injection starts, to 2-3 weeks later. And many times scientists can tell the difference between induced quakes and regular ones because the pattern of induced quakes propagate the same way that the injected water does, as it moves thru the rocks.
In Arkansas, they've been seeing lots of quakes since 2009, over 700 in the 6 months. Though mostly between magnitude 1 to 4. Much too large to be associated with injection of fracking fluid, at least at first glance.
researchers with the Arkansas Geological Survey say that while there is no discernible link between earthquakes and gas production, there is “strong temporal and spatial” evidence for a relationship between these quakes and the injection wells.
WTF "temporal and spatial" ? What is this a rerun of Star Trek, The Next Generation? What that means is the time of the fracking fluid injection fits into what we know about induced quakes, and the injection well was also close enough to the epicenter of the quake to also fit known models.
I also found a map of injection wells and quake epicenters. On page 3, if you zoom in, look for the town of Guy, just south you will see a cluster of dots, these are quakes, at the northern tip of the quake swarm is a triangle, thats an injection site.
SO what is happening in Arkansas is a swarm of quakes that are too strong to be normally associated with injection induced quakes, but are very close to one injection well and not too far from 2 others. And the quakes are occurring at a time of active fracking fluid injection, thats that time and space crap again, "temporal and spatial". And of course a blogger like me always knows more than any scientist, a sort of mythic ethos.....
Scott Ausbrooks, geohazards supervisor for the Arkansas Geological Survey, told the AP that geologists believe the seismic activity is either a naturally occurring swarm, or could be related to natural gas exploration in the region. According to Ausbrooks, geologists don't believe production wells are the problem, but haven't ruled out injection wells that dispose of "fracking" wastewater as a culprit. The earthquakes have been occurring near several injection wells.
Ok.... that Scott dude is obviously a brilliant scientist.... ahem.
Is the Fracking fluid injection causing these quakes, if injections are causing the quakes... its on a totally different scale then whats been seen before, and back in 1811 there were some major shaking going on, mag 8 maybe 9.
In researching I found some cool links I wanted to share.