60 Minutes presented a segment on the dramatic increase in Oklahoma earthquakes and its relation to the increase in oil production. OK had an average of 3 magnitude 3.0 or greater per year before 2009. Last year they had 907 that were 3.0 or greater. The geologist on the segment said cause was the pumping of the waste water from the wells into the Arbuckle formation, a layer of the Earth’s crust much deeper than the layer from which the oil and water were initially extracted.
I don’t think they gave an adequate explanation of why they have to re-inject the water so deeply. Why can’t they re-inject the waste water back into the layer from which it came? There were a few words about contamination of the fresh water aquifer, but if if wasn’t contaminating anything before it was extracted, why would it contaminate anything if it was put back in the same place?
If the oil is produced via fracking (and I don’t know if it is), fracking fractures rock structures allowing more water and contaminants to seep through afterwards, so they’d have to put the stuff back in lower to keep it out of the aquifer.
This is not true. The formations they are fracking are well below the aquifer that they could not seep into the aquifer. Otherwise, the oil and fracking solution would seep into aquifer as well.
No, I suspect the reason it is injected that deep it is mainly because there is adequate volume in the Arbuckle formation to accept the amount of brine being injected. I will admit, however, I did not see the 60 minutes piece.
I don’t know if this is related or not, but I was just reading the other day that the North American tectonic plate isn’t as stable as they used to think it was. Apparently this is due to it being thinner in some places than they used to think it was. So it’s not that it’s shifting around like you have two plates sliding against each other in California, but rather you’ve got thin and thick bits of the same plate floating on all the hot gooey stuff underneath and the varying densities put vertical stresses on the plate and cause earthquakes.
This might be causing some of the earthquakes that are being blamed on fracking.
I doubt that this has any relevance as to where they inject the water, but it does relate to the earthquakes mentioned at the beginning of the OP.
There are three many reasons for this choice. Here are some important ones :
1> The aquifer for reinjection needs to beEPA Exempt. In short, you have demonstrate that the aquifer will not be used for drinking water anytime now or in the future (its more than that but this is a simplification)
2> The Arbuckle formation is below all the oil & gas formation layers discovered so far and it also does not produce any oil & gas. See the first link for a 3-D image. So you don’t risk contaminating a potential reservoir.
3> The Arbuckle formation very readily accepts water at low pressures (underpressured) whereas other layers take a lot more pressure to accept water.
If they inject the water back into a producing formation,they can dilute nearby wells and then they risk reducing oil production and higher costs. Also, the layer (shale) does not accept water easily - so you need higher pressures to re-inject.
See above.
I am not a geologist and the above information is gathered over time from conferences/ internet.
The wastewater isn’t just water: it contains the various chemicals used in fracking, which include methanol, toluene, benzene, and hundreds of others, many of them ‘trade secrets.’ cite
I can’t see any justification for allowing these things to be secrets. To affect the ground all live upon is no different to affecting the sky that covers us all.
After the recent Indian Temple firework explosions ( which are not rare ) I recalled that in 19th century Britain fireworks were made at home, with gunpowder, as a cottage industry. Regulations were fiercely opposed and neighbours found their homes destroyed by accident… There was a compelling case for stopping the practice on general welfare.
And if the compounds are harmless what reason to keep their composition secret ? Most people will not be duplicating fracking juices; and if competitors copy the formula because it is good, where’s the harm to the company: only one firm will be fracking an area at any one time.
And finding out the optimal mix would be a benefit to science ( just as aircraft makers don’t keep safety practices secret from everyone else for fear of competition ).
I’m not an expert and I don’t know if you are or not, but Scientific American, which I take to be a reasonably reliable source, says fracking compounds may indeed be leaking into the aquifer.