Predicting calcite deposition in krafla boreholes

The only part of the Krafla geothermal system where calcite deposits have been observed in boreholes is the Leirbotnar upper production zone (including well KJ-9 that taps both zones), which is liquid dominated at temperatures of 190–210°C. Flow from this part is needed to sustain the low pressure step of the generating turbine. Comparison of wellhead and deep water calcium concentrations has been found the most useful method of predicting the extent of deposition. The deposits generally appear to form above the calculated depth of flashing, and geometric changes in the well may affect the location of their formation. Flow monitoring is the best way of predicting time of blocking.