I've been having eyeball issues, so this post may be more poorly edited than even my usual - and I'm not looking up links tonight, either.
I earn my living making and selling chemicals used in fracking wells, so I'm fairly familiar with what happens when they do that. I've followed a lot of what's been written on the environmental problems, including seismic ones, that are attributed to fracking, and I don't think of myself as overly biased. I have seen some really major messes that oilfield activities have caused, like the big treeless patch that was down near Smackover, Arkansas for most of the last century.
First, a very brief review of what a (modern) frac job is: it is the practice of pumping a lot of water (3,000,000 gallons +/-?) down the pipe in a newly drilled well with enough pressure (~8000 psi) and at enough rate (~3000 gallons/minute) to start a big crack in the hydrocarbon-laden rock at the bottom of the well. The water typically will contain less than about 0.5% of a selection of not-very-toxic chemicals (the ones my company sells) along with a lot of sand (a million pounds?) or a ceramic lookalike to sand. The chemicals are in there to reduce the pumping pressure and help carry the sand to bottom: the sand is there to get washed back into the big crack in the rock so that the crack doesn't close up again when they quit pumping. Instead, it "props" the fracture open so that the oil (or gas) that is in the rock can flow back to the pipe, out of the well, and end up as gasoline in your car. The pumping of the job might take a week or two, in four-hour episodes. The oil will continue to flow for a couple of years or more.
There don't seem to be any documented cases of earthquakes (of the feelable sort - very sensitive seismometers are sometimes used to measure how the fractures are forming) caused directly by a frac job. My take on this is that a piddly 3 or 10 million gallons just isn't enough to irritate Mother Earth into quivering. As others have pointed out above, though, you can inject enough fluid to promote whole swarms of little-ish quakes. The area near Prague, Oklahoma is a good example. If memory serves, they were disposing of maybe a million gallons per day of oilfield water into each of several wells there, and for months on end. The criteria for selecting the wells to put this into were almost certainly 1) proximity to wells producing water that needed to be gotten rid of 2) good mechanical integrity up near fresh-water zones, and 3) a bottom end in rock that wasn't a profitable source of oil but would accept disposed water if you pumped hard enough. Criterion 4), location away from subsurface faults that might fail with enough added water, was probably never considered at all.
Another example is a swarm of earthquakes near Youngstown, Ohio a few years back. The situation was similar, except that the water for their disposals came from Pennsylvania, where disposal wells were illegal. An immense amount of water was used to frac wells in Penn. It flowed back to surface with all the natural gas that the frac jobs freed up, and was wonderfully contaminated by all the salt that cohabited with the gas down in the Marcellus Shale. It couldn't go in the rivers, so it got loaded in railcars and sent to Youngstown. So at least there, fracking did actually cause quakes - one of 5+ magnitude, IIRC, but didn't do so directly. (My last trip through Youngstown was forty years ago, and at that time it looked as if being leveled by earthquakes might have been an improvement...)
The reason that water out of wells is typically reinjected deep into the earth is because it's too nasty to treat otherwise. The salt content, including table salt, calcium, magnesium, sometimes barium, and sometimes sulfates, make it largely impractical and uneconomical to purify. Even if you could distill it, all those salts would still need to be dealt with. You could take a lot of it to Smackover, Arkansas, and dump it on the ground like they did in 1915, but it would just make another big treeless patch there.
Solutions? There is a lot of work in our industry to find ways to reuse the salty "flowback" water on multiple frac jobs. More planning in where to drill disposal wells could help. This $50 per barrel oil price is having a chilling effect on the number of frac jobs being run, but I'm not personally to crazy about that solution...
According to this site, the injection of wastewater is "similar" in North Dakota, which has not been hit by anything approaching Oklahoma's level of quake activity. (A few seismic events have been reported, at least one in the middle of the Bakken region, but the situation is nothing like in Oklahoma.)
He added that there are similar wastewater disposal wells in North Dakota without any reported increase in earthquake activity there.
There is obviously something different about what's going on in ND and OK. Is it related to the amount of waste water disposed? The geology of North Dakota vs. Oklahoma?
I'm not expecting anyone here to have all these answers, but I figured that making some of my questions public might help get them some answers. I've done plenty of googling, but there just isn't a lot of science out there on why North Dakota has been relatively stable while Oklahoma shakes like a leaf.
It's the geology would be my bet. There are lots of little quakes over near Ft. Worth, Texas, where significant water disposal started maybe ten years ago. (Quakes started after disposal did). There aren't any around Midland, where they've been running disposals for perhaps fifty years. I don't know enough of the geology and of the preferred disposal zones to do much comparison, though.
Im curious why would relatively small earthquakes caused from fracking be more of a threat then flammable watter caused by fracking.
This should be enough to stop fracking permanently, the world is already running low on drinking watter anything that can potentially poison our reserves should be illegal.
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According to this study it seems as if fracking induced seismic activity is very rare, but does happen sometimes.
In the study 77 earthquakes (we would call them tremors as they were hardly felt by people if felt at all), which were closely related spatially and temporally to active hydraulic fracturing operations, were identified in Poland Township, Mahoning County, Ohio. I'm no seismologist, but just by reading the abstract, it seems as if the seismic activity was directly induced by the fracking itself. The study also mentions another earthquake sequence that occurred 18 km to the northwest which was correlated with wastewater injection instead of hydraulic fracturing.
And the source is credible; not just some wacko greenies writing nonsense on the net.
Edited by Pressie, : Added part in brackets and last sentence
According to this site, the injection of wastewater is "similar" in North Dakota, which has not been hit by anything approaching Oklahoma's level of quake activity.
Jon,
As has been discussed, fracking also involves waste water but in smaller amounts. The article you linked to is about fracking and indicates a tenuous or no link between earthquakes and fracking. The article discusses earthquakes of magnitudes of less than 3 being associated with fracking. Or maybe not associated if the article is to be believed.
In short, the article does not bring up any controversy with the stuff already posted here. I'll also note that the article is about what does not on in Oklahoma. So it is no help with showing an anomaly with things not happening in North Dakota if the oil production there is primarily fracking.
Edited by NoNukes, : No reason given.
Edited by NoNukes, : No reason given.
Je Suis Charlie
Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass
We find the same in the traditional coal mining areas in my country. That gas is a result of what happened in mining relatively shallow coal in underground operations. As hydraulic fracturing has never been done on commercial scale in my country, it means that fracking is not to blame for it.
It also happens in areas where deep gold was mined (>2000 m). Deep gold mining has resulted in a lot of tremors. There the coal is found a few hundred meters above, but the coal was never mined.
Any mining activity would result in more seismic activity.
At the same time most people also have to realise that explosions by dynamite in any underground mining operation register as seismic activity on the instruments used by seismologists.
As has been discussed, fracking also involves waste water but in smaller amounts. The article you linked to is about fracking and indicates a tenuous or no link between earthquakes and fracking. The article discusses earthquakes of magnitudes of less than 3 being associated with fracking. Or maybe not associated if the article is to be believed. ...
So it is no help with showing an anomaly with things not happening in North Dakota if the oil production there is primarily fracking.
The part I quoted was specifically about wastewater. The claim was that wastewater injection in Oklahoma and North Dakota are similar. Yet North Dakota doesn't see the earthquakes Oklahoma sees.
An answer to this question has been given several times in this thread including in my own post. Water is pumped under ground both during fracking and during more conventional drilling, but the volume of wastewater disposal in conventional drilling dwarfs the water in fracking operations.
When similar is used in the article you refer to, did that say anything about the volume compared to conventional drilling? No. All that is said is that a similar operation is carried out. Therefore it does not contradict the answer you've been given repeatedly.
Je Suis Charlie
Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass
The reason that water out of wells is typically reinjected deep into the earth is because it's too nasty to treat otherwise. The salt content, including table salt, calcium, magnesium, sometimes barium, and sometimes sulfates, make it largely impractical and uneconomical to purify. Even if you could distill it, all those salts would still need to be dealt with. You could take a lot of it to Smackover, Arkansas, and dump it on the ground like they did in 1915, but it would just make another big treeless patch there.
It seems to me that the issue is that the amount of such water slurry material has increased dramatically with the newer fracking wells, and that this has caused the increase in noticeable quakes, plus they are doing it closer to places where people live, again making it more noticeable.
Is it a problem in itself? probably not. Is it something to be ignored? probably not. It seems to me that a bigger concern is the possible contamination of potable water aquifers that would permanently render them unsuitable for consumption.
Personally I am looking at roof mounted solar panels and a small wind generator (as seen on sailboats) to decrease my dependency on fossil fuels (sorry).
It seems to me that the issue is that the amount of such water slurry material has increased dramatically with the newer fracking wells...
That might have something to do with it. Earthquakes are starting to be reported in small numbers in North Dakota where, perhaps, they are switching to using some of the techniques in use in Oklahoma.
plus they are doing it closer to places where people live, again making it more noticeable.
I think any relevant earthquakes would make it into the literature as I believe geologists pretty much have the whole country monitored for any seismic activity simply as a matter of data collection.
Is it a problem in itself? probably not. Is it something to be ignored? probably not.
It does have the tendency to knock peoples' houses down .
As you mention, too, there is the possibility of contamination. It's made even worse by the fact that the equipment isn't constructed to withstand earthquakes, making it possible for the piping to break underground if the earth moves too much.
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