Drilling a multilateral closed-loop geothermal well

Abstract

A method performed on a wellbore system with a first surface wellbore extending from a terranean surface to a subterranean zone, a second surface wellbore extending from the terranean surface to the subterranean zone and a plurality of connecting wellbores in the subterranean zone each connecting the first and second surface wellbores. A lateral wellbore is drilled using a drill string extending through the first surface wellbore. While drilling, flow of drilling fluid from the drill string is sealed against returning towards the first surface wellbore through the connecting wellbores.

Dependencies are inferred from the claim text.