I think that having a gas well in your yard is cool in view of fuel and gas
prices. A low yield one is probably better because it will last a very long time
(think about 31 years worth of gas bills for a house at todays prices - wow,
that's about two or three cars or half a house - also 1000 foot wells at $8000 
all finished are pretty cheap imho ...). I have read about places where lighting
cnadles in the basement is a bad idea ... methane seeps in from the ground.

I think that adding a line filter unit at both ends of the cable will fix your
lightning problem and might prolong the life of your pic device. A line filter
is the inline 'box' type of RLC filter used to remove EMI from mains wiring.
E.g. from Corcom etc. The effect you are seeing is likely caused by the wire
going out acting as an antenna and coupling common mode current into the GFI.
That will trip it for sure. In a way you have a radio receiver of the same type
as a coherer ... getting the 15-20 mA needed to trip a GFI from 100 feet of
'antenna' connected to the well that will pick up ground currents is probably
trivial even if lightning strikes are fairly far off.

There is a reason for which mains hauling switchgear is more intelligent than a
GFI and makes several 'self repair' attempts in such a fault case, before giving
up. Typically after a nearby lightning strike the breakers restart after 60
seconds, and try it again three times, waiting successively longer times. If
there is a short or repeated trips within that amount of time they stay off and
operator intervention is needed. I don't think that you want to copy this
behavior. The line filters will likely reduce the sensitivity of your coherer
receiver to reasonable levels. They should have no impact on the normal GFI
functionality. I don't know what your code says about outdoor electrical
installations but I am fairly sure that this type of thing (30 meters of mains
to an outside building just like that) is totally illegal in most places when
not installed and checked by an authorized electrician. I don't even want to
think about what permits would be needed to use such an electrical installation
anywhere near a producing gas well, even if it would not be next to a house.

Peter


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