Fig. 4

Correlations between scale rate at the wellhead of the production pipe and different parameters with indication of error bars. Data points labeled with site number. Red data points: reliable data. Grey data points: less reliable or particular data (site 9: many different pumps, site 5: scale thickness according to facility operator). a Scale rate against \(\Delta\) log (pCO2) between reservoir and wellhead. b) Scale rate against \(\Delta\) between reservoir pressure and wellhead pressure. c) Scale rate against \(\Delta\) pH between reservoir and wellhead. d) Scale rate against reservoir temperature. e) Scale rate against \(\hbox {SI}_{{calcite}}\) at the wellhead. f) \(\Delta\) between reservoir pressure and wellhead pressure against wellhead \(\hbox {SI}_{{calcite}}\). The black line shows the theoretical pressure dependence of \(\hbox {SI}_{{calcite}}\) as calculated with PHREEQC. Linear regressions k(x), f(x), g(x), and h(x) between parameters and scale rate