Inspection of drilled well at the Borgen school in Asker community, Akershus

A drill hole inspection is carried out with an optical telemetric reviewer at logged temperatures, electric conductivity and natural gamma radiation in a 165 m deep drilled well at the Borgen school. The aim of the logging was to obtain data for evaluating the geothermal potential of the well. The optical logging shows that the rock (shale, siltstone and noduled lime) generally is only slightly cracked.. The temperature log shows only slight temperature increment, 0.56 o C/100 m, down to about a depth of 100 m. From 100 m the temperature gradient increases to 0.98 o C/100 m and the temperature is about 6.8 o C at a depth of 160 m. A marked increase from 160 m may indicate a water flux at this depth. An observed crack in the optical log at the same depth confirm that this may be the case. The conductivity is constant and low, about 225 microsec/cm, along the entire drill hole except for the top 6 m of the hole where it is lower. The natural gamma radiation is at a low level, about 75 cps, along the entire hole. A marked decrease between 60 and 70 m indicates another rock type, chalk enriched sandstone, which probably has somewhat lower potassium content than the rest of the hole. The deviation measurement shows that the hole turns towards north west with a horizontal deviation of 21 m at the bottom