Sanyal Temperature Classification: Low Temperature
Reservoir fluid between 150°C and 190°C is considered by Sanyal to be "low temperature."
"The mobile fluid phase in these reservoirs is liquid water. A number of commercial power projects have been operated over the last two decades using geothermal resources in the 150° to 190°C range, the latter temperature being the limit of operation of commercially available downhole pumps today; geothermal water over most of this temperature range must be pumped because the fluid does not have sufficient energy for self-flow at a commercial rate. However, at the upper end of this temperature range wells may be either be pumped or self-flowed (if the reservoir flow capacity is relatively large). Well productivity for such a resource would be less than 7 MWe, the typical range being 3 to 6 MWe. While temperature tolerance for commercial pumps may someday exceed 190°C, the higher vapor pressure at higher temperatures might reduce the available pressure drawdown sufficiently to make pumping less attractive than self-flow. Therefore, the 190°C limit for this range is reasonably well defined" (reference: http://www.geothermal-energy.org/pdf/IGAstandard/SGW/2005/sanyal1.pdf).