geo thermal

I'm considering replacing my air to air heat pump with a geothermal system.

any advice?
stray thoughts?

drilling a well to tap water source (our community water well is over 280 ft deep near the bottom of the Devonian strata---just above the Silurian--- some winters, I can smell the hydrogen sulfide of the silurian ---Would I need to go this deep to assure a continuous supply of water?
vs
coils buried in the ground ( I have the space)

federal tax credits of 30%, state of 6%

What would you...

geo thermal