CONTINUOUS TEMPERATURE OBSERVATIONS IN THE HAWAII NSF/ICDP BOREHOLE - RESULTS AND MODELS

Abstract

The borehole of the Hawaiian Scientific Drilling Project (HSDP, 3109 m) penetrates zones of enhanced permeability and low temperature. Transient temperature conditions during different hydraulic stimulation's were monitored using fiber optical measuring (DTS). Several bore hole sections of the Hawaii ICDP hole can be distinguished by increasing or decreasing temperatures with time. The following combined thermo-hydraulic modeling suggests that a downstream of freshwater from the mountain range strongly influences the thermal conditions in the upper part of the borehole. The lower part is also affected by down-streaming freshwater, however, with lower flow velocities and additionally by a circulation of saltwater from the nearby ocean.