Jökull - 01.12.1987, Page 30

ishing and that the exploitable area can be increased in
the near future. Estimates of the generating capacity of
the area so far drilled suggest that it can sustain power
production of about 55 MW for 30 years (Leirbotnar 30
MW, Suðurhlíðar 20 MW and Hvíthólar 5 MW). The
present power production capacity is about 30 MW and
most of the unexploited power would be obtainable
from the Leirbotnar field which was hit severely by the
magmatic gas problems. In the light of recent findings it
should be possible to extend the area of exploitation of
the Leirbotnar field considerably. It seems resonable to
assume that the 60 MW for 30 years, needed to fully
utilize the power plant in Krafla could be drawn from
that area. There are also strong indications that the
longevity of the field could be extended considerably by
reinjection of upper zone Leirbotnar fluids and of ef-
fluent from the separating plant into the lower zone. On
the other hand more research would be needed before
further development of the area could be recommend-
ed.
The model of the Krafla geothermal system presented
here is in general agreement with observations in the
area and has proved adequate for short term prediction
of its behaviour.
ACKNOWLEDGEMENTS
Mr. G. Gíslason, Dr. H. Torfason, and Mr. Ó.B.
Smárason are thanked for reading the manuscript and
making useful comments.
REFERENCES
Ármannsson, H. & Benjamínsson, J. 1986. Changes of gas con-
centrations in Krafla geothermal fluids. Proc. 5th Symposium
on Water-Rock Interaction. Reykjavík. 13-16.
Ármannsson, H. & Hauksson. T. 1980. Krafla. Chemical com-
position of fumarole gas (In Icelandic). Report No.
OS80027/JHS 16. Orkustofnun. Reykjavík. 51 pp.
Ármannsson, H.. Gíslason, G. & Hauksson, T. 1982. Magmatic
gases in well fluids aid the mapping of the flow pattern in a
geothermal system. Geochim. Cosmochim. Acta. 46. 167-
177.
Árnason, B. 1976. Groundwater systems in Iceland traced by
deuterium. Icelandic Science Society Publication. 42,236 pp.
Benjamínsson, J. 1985. Comparison of gases from fumaroles
between the years 1979 and 1984/1985 (In Icelandic). Report
No. OS-85061/JHD-26 B. 28 pp.
Björnsson, A. 1985. Dynamics of crustal rifting in NE Iceland. J.
Geophys., 90, 151-162.
Björnsson, A., Sœmundsson, K., Einarsson, /'., Tryggvason, E.
& Grönvold, K. 1977. Current rifting episode in North Ice-
land. Nature, 266, 318-323.
Björnsson, A., Johnsen, G., Sigurðsson, S., Thorhergsson, G.
& Trvggvason, E. 1979. Rifting of the plate boundary in
North Iceland 1975-1978. J. Geophys. Res., 84. 3029-3038.
Böðvarsson, G.S., Benson, S.M., Sigurðsson, Ó., Stefánsson,
V. & Elíasson, E.T. 1984 a. The Krafla geothermal field,
Iceland. 1. Analysis of well test data. Water Res. Res., 20.
1515-1530.
Böðvarsson, G.S., Pruess, K., Stefánsson, V. & Elíasson, E.T.
1984 b. The Krafla geothermal field. Iceland. 2. The natural
state of the system. Water Res. Res., 20, 1531-1544.
Böðvarsson, G.S., Pruess, K., Srefánsson, V. & Elíasson, E. T.
1984 c. The Krafla geothermal field in. Iceland. 3. The gener-
ating capacity of the field. Water Res. Res., 20, 1545-1559.
Darling, W. G. & Ármannsson, H. 1986. The behaviour of H
and O stable isotopes in the Krafla geothermal flow system.
Proc. 5th Symposium on Water-Rock Interaction, Reykja-
vík, 155-158.
Einarsson, P. 1978. S-wave shadows in the Krafla caldera in NE
Iceland, evidence for a magma chamber in the crust. Bull.
Volcanol. 43. 1-9.
Einarsson, P. & Brandsdóttir, B. 1980. Seismological evidence
for lateral magma intrusion during the July 1978 deflation of
the Krafla volcano in NE-Iceland. J. Geophys.. 47. 211-220.
Gíslason, G., Ármannsson, H. & Hauksson, T. 1978. Krafla.
Temperature conditions and gases in the geothermal reser-
voir. (In Icelandic). Report No. OS-JHD-7846, NEA.
Reykjavík, 84 pp.
Guðmundsson Á. 1983. The geology of the Krafla Suðurhlíðar
field (In Icelandic). In "Ravens' Congregation" on the status
of the Krafla geothermal power station 2nd and 3rd March
1983, Krafla Power Station. Akureyri. Iceland. 77-85.
Guðmundsson, G. 1983. Temperature and pressure in the
Krafla Suðurhlíðar field (In Icelandic). In "Ravens' Congre-
gation" on the status of the Krafla geothermal power station.
2nd - 3rd March 1983. Krafla Power Station. Akureyri Ice-
land, 86-101.
James, R. 1962. Steam-water critical flow through pipes. Proc.
Inst. Mech. Eng. London. 176, 741-745.
Kristmannsdóttir, H. 1978. Alteration of the bedrock in the
Krafla geothermal system (In Icelandic). Report No. OS/
JHD-7854. Orkustofnun. Reykjavík, 29 pp.
Pruess, K.. Böðvarsson, G.S., Stefánsson, V. & Elíasson, E.T.
1984. The Krafla geothermal field, Iceland. 4. History match
and prediction of individual well performance. Water Res.
Res., 20. 1561-1584.
Sigurðsson, Ó. 1978. The flow characteristics of the upper zone
of the Krafla geothermal field (In Icelandic). Report No.
OS/JHD-785I, Orkustofnun, Reykjavík. 36 pp.
Sigurðsson, Ó. & Stefánsson, V. 1977. The transmissivity of
Krafla boreholes (In Icelandic). Report No. OS/JHD-7727,
Orkustofnun, Reykjavík 77 pp.
Sigurðsson, Ó., Steingrímsson, B. & Stefánsson, V. 1985. Pres-
sure buildup monitoring of the Krafla geothermal field, Ice-
land. Tenth Workshop on Geothermal Reservoir Engineer-
ing, Stanford University, January 22-24. 1985. 6 pp.
Stefánsson, V. 1980. Investigation on the Krafla high temper-
ature geothermal field (In Icelandic. English summary).
Náttúrufræðingurinn. 50, 333-359.
28