A recently published report compares geothermal well performance for hypothetical supercritical wells, with existing subcritical geothermal wells in the Taupō Volcanic Zone (TVZ), New Zealand. It documents output forecasts for 4500 to 6000 metre deep geothermal well configurations across a range of reservoir temperatures from 450 to 600°C. The GFlow well bore simulator, assuming the fluid was pure water, identified a range of outputs (as thermal and exergetic power) that might be possible from supercritical wells, and compared these with subcritical production well data from 6 TVZ geothermal fields.
It was observed that TVZ supercritical geothermal wells might produce the work equivalent of larger subcritical geothermal production well, and up to four times power output of the median subcritical types of production well from the data set. Well head temperatures were forecast to be greater for supercritical wells (250°C - 420°C) than recorded in the subcritical production well data set (<264°C). The study includes IDDP-1 output test data from 2010 – 2011 and modelled predictions for a 5000m Icelandic supercritical well developed as part of IDDP (Iceland Deep Drilling Project) preparatory work.