Linda - the object of 'fracturing' is to fracture ONE formation only.
Oil Reservoirs always have a 'top seal' - a TOTALLY impermeable formation above them - Limestone, Dolomite, Shale, Salt, Chalk, Tite Sand (sands can also be totally impermeable due to cementation).
The #1 Design Criteria of a proper frac job is to prevent breaching that seal. If that seal is breached - the reservoir is (can be) totally ruined - because it starts leaking like a sieve and the oil and gas do NOT come up the hole as designed (well, not nearly as well) - but instead go up through the top seal. And even if they ARE breached - the frac material is not what is going to move - it is going to be the oil and gas liquids. The 'frac' liquid is almost entirely recovered from the frac job right back out of the hole into which it was pumped. The solids stay in place - no way in hell for them to move.
No - areas that are 'fracced' are in NO WAY 'written off'.
Water 'Tables' are very 'shallow' phenomena - from a few inches below the surface to possibly as deep as 2,000 to 3,000 feet in places. That is extremely rare - most water tables are no more than 500-600 below the surface.
Water table itself is a confusing term to the layman.
What is meant by water table is the depth at which water is found - whether salt water or fresh water.
The BASE of the FRESH WATER table is what I was referring to above.
What most non-geology people do not realize is that BELOW THE MAXIMUM DEPTH at which 'fresh water' is found - the 'earth' is STILL 100% saturated - there are no voids in nature.
What is the ground saturated with .... below the fresh water table ?
SALTWATER (*1) - up to 3-4 times saltier than ocean water. Some of that water is extremely nasty stuff - such as the 'black water' that is found in formations in the Delaware Basin - Saltwater, with nasty, nasty sulfide compounds that make it some of the most foul smelling, tasting, toxic crap you have ever seen.
Fracking is NOT the 'invention of man'. Nature does it herself - all the time, all over the place - but doesn't have the 'maximum entropy driver' needed to design 'frac jobs' that confine the fractures to a single formation.
What are those NATURAL fracs called ?
"Faults" is the term most people are familiar with - and they are EVERYWHERE - not just in earthquake prone areas.
So, those that attempt to portray 'fraccing' as an 'evil, environmentally unsafe and unsound practice' are one of two things:
1.) Extremely ignorant on the topic they pillory
-or-
2.) Deliberately prevericating.
Are there PROBLEMS ? OF COURSE THERE ARE - name me even one 'man made' activity that doesn't have 'environmental consequences'. However, as stated above, it behooves the oil industry to have GOOD FRAC jobs that cause no other damage - because when damage occurs - the industry has just wasted money on the frac job (up to millions of dollars per frac) and damaged their own property also. PROFIT, not destruction, is the goal of all good business - and when things get destroyed, the profit almost always disappears and becomes nothing but a hole in the ground at which you chuck money.
(*1) There are also pockets of 'hydrocarbons' that the ground can be saturated with - but for all practical purposes the 'saturation liquid' is saltwater.
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