Please use this identifier to cite or link to this item: http://hdl.handle.net/1946/7763
Þeistareykir high-temperature geothermal field, North-East Iceland : estimation of reservoir conditions and evaluation of pressure interference between wells
The Þeistareykir high-temperature geothermal field is located in northern Iceland. Seven
deep boreholes have been drilled there since 2002.
Temperature and pressure logs, measured during different operational stages of the wells,
were analyzed to estimate formation temperature and initial pressure, as well as the
possible location of feed zones in the wells. A new interpretation supports the hypothesis
of an up-flow around well ÞG-1. It is possible that the up-flow does not spread as far to the
west as was previously assumed.
The highest temperatures measured in the new wells ÞG-5B and ÞG-6 were 300°C and
311°C, respectively. The discharge enthalpy for well ÞG-5B is higher than it is for well
ÞG-5. Discharge from well ÞG-6 will possibly have similar characteristics as the discharge
from wells ÞG-1 and ÞG-3, i.e. high temperature steam.
Pressure recovery measurements in wells, which were shut in during the summer of 2008,
have been evaluated using conventional well test analysis methods. The results obtained
were compared with results of the interpretation of step-rate injection test data.
Transmissivities evaluated in this work for wells ÞG-1 and ÞG-3 are lower than previous
estimates while skin factor estimates have become more negative.
Transmissivity, estimated by the analysis of injection test data for well ÞG-5B is close to
the transmissivity estimated for well ÞG-5, or in the order of 7x10-8 m3/Pa-s;
transmissivity, estimated for well ÞG-6 is close to the transmissivity for well ÞG-3, and in
the order of 1.3 x10-8 m3/Pa-s.
There are indications of interference between well ÞG-2 and wells ÞG-3, ÞG-5, ÞG-5B,
and ÞG-6, as well as between ÞG-3 and ÞG-5. Well ÞG-1 has a limited communication
with wells ÞG-2 and ÞG-3, however.
Verkefnið er unnið í tengslum við Háskóla Íslands og Háskólann á Akureyri