IMAGE-D5.4: Strategy for Supercritical Well Design

Typical high-temperature geothermal wells reach 2000-3000 m in total depth aiming for medium to high-enthalpy geothermal fluids that reach the surface as two-phase steam or in some cases single-phase saturated steam. The Iceland Deep Drilling Project (IDDP) consortium was established in 2000 (Fridleifsson, et al., 2014b) to investigate the feasibility and economics of deep, high-enthalpy geothermal resources, and supercritical hydrothermal fluids, as possible future energy sources (Fridleifsson, et al., 2014b). 

IDDP-1 became the first well to be drilled in the project. Drilling came to an early end as drilling problems arose and fresh glass cuttings indicated drilling into magma. Nevertheless, the well was completed and flow tested for approximately two years with intermittent shut-in stops. The well became the hottest producing geothermal well in the world, producing superheated steam at wellhead conditions up to 450°C, pressure of 140 bar-g and enthalpy of 3150 kJ/kg (Hauksson, et al., 2014; Pálsson, et al., 2014). Although goals of producing supercritical steam, IDDP-1 was considered a success from scientific and engineering standpoint. 

Drilling of the next well in the series RN-15/IDDP-2 began on 11th of August, 2016, and has now been completed. The IMAGE project has been a part of the design phase by involving scientists, engineers and other technical personnel. Strategy and design of a deep well aiming for supercritical conditions, its challenges and limitations is described in this report.