Jökull - 01.12.1987, Page 45

TABLE 5. Geothermometry results
for gas samples from hot pools
and shallow wells in the Krísu-
vík field (°C).
No. co2/n2 co2/h2 DP
24 197 264 315
25 263 237 347
26 228 262 -
27 244 268 320
28 257 178 306
29 188 251 360
30 252 216 260
31 252 211 296
32 252 227 328
33 241 226 316
34 219 221 265
35 219 220 281
36 218 175 244
37 270 244 -
38 290 223 -
39 239 247 -
40 - 238 336
41 - 228 -
42 292 240 355
43 - 219 315
44 - 232 344
45 195 288 225
46 248 297 -
47 278 287 248
aGeothermometer of D'AMORE
and PANICHI (1980).
gives temperatures which are on average 7° and 13°C
lower, respectively.
In an earlier section of this contribution it was pointed
out that the N2/Ar ratios in some of the steam samples
were lower than 37 (the ratio in cold water in equilib-
rium with the atmosphere). Such low ratios would occur
in secondary steam if the primary deep water had been
partially degassed at elevated temperature. Partial de-
gassing of this kind would lead to underestimation of
condensation in the upflow. Consequently, C02 temper-
ature, when corrected for condensation by Zb and Zc
would be too high; by about 20°C for samples with N2/Ar
ratios of 25. Atmospheric contamination raising the N2
concentrations in the samples would have the opposite
effect. It is, therefore, concluded that 270-280°C is a
reasonable estimate of C02 temperatures for the
Sveifluháls geothermal system.
H2S-temperatures in the Sveifluháls area are in the
range 231-279°C except for the Ketill sample (no. 21)
which is lower. Correcting the H2S-temperatures for
condensation effects according to Zb and Zc lowers them
on average by 6°C and 13°C, respectively. The samples
with the highest H2S would thus be indicative of sub-
surface temperatures as high as 260°C. The discrepancy
I
I
ii
E
(0
V
TJ
%
"5
(/)
<J)

20 40 60 80
% Zb
Fig. 9. The amount of H2S dissolution in steam heated
water in relation to the extent of the steam condensa-
tion. — Samband milli hluta H2S sem leysist upp ígufu-
hituðu vatni og þéttingar.
43