Results of borehole logging in CO2 wells, Dh1-CO2-07 and Dh2-CO2-07, Longyearbyen, Svalbard
NGU has carried out borehole logging in two wells just outside Longyearbyen. The wells were drilled to locate deep reservoir sandstone formations which may store CO2 from the local coal combusting power plant. Logging parameters were temperature, fluid conductivity, natural gamma, rock resistivity, seismic velocity, caliper, relative density and borehole deviation. Both wells were logged to a depth of 440 m. Deeper parts were blocked. Blocking is related to cut drill string in a 25 m thick fault zone of highly fractured shale that collapsed. Therefore there was no logging performed in the deepest part of the wells (820m). The well did not reach the main reservoir that was planned to be in Late Triassic sandstone. The various logging results show good correlation between the geophysical logs and the lithological units. Sandstones are indicated with low gamma radiation, and increasing seismic velocity and apparent resistivity. However, more on actual results the prosperities of the most suitable formation for CO2 storage could not be mapped in these wells. This will be done in a new well in Adventdalen which is to be drilled August 2008.