Fracking has nothing to do with horizontal drilling. Fracking is used to increase the connectivity of the reservoir to the wellbore, in the case of low permeability reservoir. For geothermal applications there is no reason to pick the low perm and increase the cost of well completion.

Horizontal directional drilling is a very established field, which is very technologically intensive and some of the things we can do in this area are nothing short of amazing. Basically any trajectory can be executed, including some smart things like underground loops. Couple this with electric submersible pumps (ESP), which help to increase the flow and potentially run water through several cycles to maximize the contact with hot payzone before getting it to surface and you can do many interesting things.