Thank you for your reply. It has given me the factors to consider and the terms to look for. I’m going to cross verify the values you have quoted and if it is indeed as bleak, I’ll just temper my expectations.
But I’m not giving up on it totally yet. What I’m still not sure is how geothermal cooling can provide more heat exchange as compared to the system I’m proposing. At most geothermal systems also only have a few tens on meters of piping underground.