Enhanced and Advanced Geothermal Systems (EGS and AGS) are new methods of creating geothermal installations that have already been demonstrated to potentially increase electric power production by a factor of greater than 10 when compared with more conventional methods. Some involve fracturing the rock between injector and producer wells, and some rely on drilling wells to convey closed loop fluid systems to take heat from the rock.
Compared with conventional hydrothermal wells, they are technically challenging to drill. In particular, very accurate well positioning, generally including horizontal wells, will be required. The oil and gas industry can already drill accurate directional wells and this capability to position the well is directly transferable to some of the first EGS and AGS wells because they are likely to be drilled at temperatures familiar to oil and gas drillers. But to make EGS and AGS wells more economically interesting, they will need to be drilled at higher temperatures which are currently beyond the capabilities of oil and gas drilling equipment.
Even the claimed 175°C operating capability of oil and gas technologies is challenging for the economics of geothermal drilling because equipment operated at this maximum temperature limit exhibits low mean time between failure and/or service. Therefore, the industry needs a step change in its approach to the temperature capabilities of downhole equipment.