corrosive species and scaling in wells at olkaria ... - Orkustofnun

D =
HCl
[ mHCl ]
[ mHCl ]
Temperature dependence is given by (Simonson and Palmer, 1993):
log D HCl = -13.4944 – 934.466/T – 11.0029×logρ + 5.4847×logT
where T = The temperature in Kelvin, as before; and
ρ = The density of solvent (g/cm 3 ).
l
v
LogHCl aqueous (ppm)
logHCl aqueous (ppm)
1
0.1
0.01
0.001
0.0001
1E-005
10 100 1000 10000 100000
Chloride (ppm)
FIGURE 18: Aquifer water HCl concentrations vs.
aquifer water chloride concentrations of
selected wells in the study areas
1
0.1
0.01
0.001
0.0001
1E-005
Olkaria East
Olkaria West
Olkaria North East
Olkaria Domes
Reykjanes
Svartsengi
Nesjavellir
Olkaria East
Olkaria West
Olkaria North East
Olkaria Domes
Reykjanes
Svartsengi
Nesjavellir
5 6 7 8
pH
FIGURE 19: Aquifer water HCl concentrations vs.
aquifer water pH of selected wells in the study areas
The density of the dilute waters from
Olkaria and Nesjavellir was calculated
using thermodynamic properties of
water and steam given by the computer
code TAFLA (Bjarnason and
Björnsson, 1995). Densities for
Reykjanes and Svartsengi brines were
calculated using densities of saturated
sodium chloride solutions provided by
Potter and Brown (1977).
The calculated concentrations of HCl
in the aquifer waters of the study areas
are presented in Table 4 of Appendix A
and depicted in Figures 18, 19, 20
respectively as a function of aquifer
water chloride concentrations, pH and
temperature.
The concentrations of HCl aq increases
with increasing aquifer water Cl
concentrations, decreasing aquifer
water pH and increasing aquifer
temperature. The water in producing
aquifers of the Olkaria wells contain
HCl in the range between ~ 1×10 -5 ppm
and ~ 5×10 -4 ppm. The aquifer water
HCl concentrations in Reykjanes and
Svartsengi are much higher, ranging
between ~0.32 and ~ 0.81 ppm and
~3×10 -2 and ~8×10 -2 ppm, respectively.
At Nesjavellir, the HCl in the aquifer
waters is in the range ~ 3×10 -5 - 5×10 -5
pm for the selected wells.
There is a variation in HCl
concentrations in the Olkaria well
fluids of about an order of magnitude
with the exception of fluid from one
well, well OW-34 which has a slightly
higher HCl concentration, than other
Olkaria well fluids (Figure 18). At
Olkaria, the variations in the HCl
concentration can be attributed to the
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