Geothermal wells. What are the best and worst sites to drill? What is the range of depths?

Question

Wikipedia doesn't provide this - as far as I could find, anyway.

Any geologists know of a map that includes average depths necessary for a functional geothermal well?

Answer 1

I also had some lecture in geothermal energy...

Basically, on average the temperature increases by

Careful, you might need a binary system (wo circuits and a heat exchanger between then) since a lot of the wells are heavy on salts and sulfurs, so very corrosive. Any motor or turbine would get damaged by them.

Best sites are found in the western states (Cali-NM-NV) and in Mexico. Also Kenya and the Philippines are promising.

Generally, valleys between mountains are places were the temperature gradient profile is sharper.
Good sites have a temperature that increases by 1°C / 10m
On average one meter drilled would cost you 1200$ so far I know.
An interesting project is the hard dry rock in the Swiss City of Basel 30MW thermal - 5MW electric. This is important... don´t forget the heat also can be sold as district heating.. so its very profitable.

Answer 2

Depending if you look for low (less than 60 deg celsius water) or high energy (More than 60 deg). The average geothermal gradient in sedimentary basin is around 28 Celsius deg/ km. You need to consider a datum depth of around 30 m where the temperature is not changing depending on the season. You have there the average yearly temperature. So, if you are in a "quiet" sedimentary basin, in the US middle west, you might have an average yearly temperature of 15 deg. If you want to reach 60 deg celsius, you need to go at (60-15)/28*1000+30 m i.e. 1637 m.
In volcanic region, the geothermal profile is much more perturbated, so you can get hot water or steam in very shallow depth, sometimes almost surface.
So the best places are places with high geothermal gradient which are often volcanic area and always linked to a volcanic past. Just look for the map of the appropriate region or country.

Answer 3

Not sure this will help you but try this site:
http://www.consrv.ca.gov/DOG/geothermal/general_info/production_wells.htm