| Abstract |
Use of the geothermal resource at Ohaaki has resulted in compaction of high-porositybut low permeability lacustrine mudstones and sandstones (Huka Falls Formation), within a well-defined 1.5 subsidence area. This area may have been the site of former sub-lacustrine hot spring activity, a pre-development outflow zone. New samples of the Huka Falls Formation fiom 21 wells were studied and compared to earlier results, to determine differencesin mineral and physical characteristics between wells inside and outside of the subsidence area. Preliminary results of petrological, grainsize, density porosity data show few, if any differences. |