I think I'll stick with fracking (without waste-water reinjection, which seems to be the actual cause of the fracking-related earthquakes), and preferably in the version that uses super-cooled propane as the fracking fluid so there's no chance of ground-water contamination at all.
Am unsure what you are talking about - seems you are mixing unalike terms here.
First - hydraulic fracturing uses water. That water is not all returned from the formation, although a lot of it is. The part that is returned by producing the well is either treated and reused on a frac on another well or, as more typical, reinjected into water disposal wells, just like the water from any other producer does.
As far as propane fraccing - whew - talk about something truly capable of an awe-inspiring explosion. Do you know what pressures are usually used when a well is fracced? Somewhere upwards of 5,000 psi up to well over 10,000 psi at the surface. If propane is used, it will be much higher as it has a lighter density and will be unable to sustain an emulsion to carry much proppant, hence it has to be injected at higher rates, and even corresponding higher surface pressures.
Would you care to be anywhere in the vicinity of a well being fracced with an explosive mixture of propane being pressured to 10,000 psi or more?
Not me.
I read the file on a well fracced in South Texas in the 70s with propane near McAllen Ranch field. The frac crew dug a ' trench 100 years away and operated the frac from there. The trench was the way to escape the lethal fireball that would have passed overhead when things went south. Not sure if it had worked if it had happened, which thankfully it did not.
