You would have to move a LOT of water, in my opinion to make such a system work. And then, it'd only kinda work for AC, and not at all for heating.
And, the thermosiphon might kinda work in the winter, but without a significant temperature difference driving it they don't work very well.
Earth ground water around here is about 55 ish. Would be okay for summer (although non ideal, need a pretty big DX coil), but is too cold for winter. The whole idea of the heat pump using the earth as a sink is, if you're pumping heat from 55 degree water, it will use less energy then pumping it from 10 degree winter air. Less sliding up the entropy curve. Ditto in the summer, when you're trying to move heat from a 40 degree coil to 100 degree outdoor summer air.
Paging Jim and 280...