Novel Carbon Resource SciencesSilica scaling has been one of the major problems in geothermal engineering. Scale prevention, monitoring and removal are necessary to counter excessive silica scaling in geothermal surface facilities and the reservoir. This study aims to characterize silica scales in terms of physical properties and chemical components. For this, the deposits are examined on the difference in density and porosity of silica scales formed in aging tank, canal and surface pipelines in the Otake and Tiwi geothermal fields, both of water-dominated system, as a measure to help in the mitigation process. Density has been found to not vary significantly across layers of the deposit for all samples. Average density of solid deposits from these two fields ranges from 2.15-2.20 g/cm^3. Apparent porosity, on the other hand, showed different 1rends in the result depending on the location of the sample in the surface facility. A homogenous porosity was observed for samples collected in surface pipelines. An increasing porosity was obtained for subaqueous solid deposits found near the aging tank. Similar trend in porosity was observed for samples obtained within the surface level of the aging tank. Iron and aluminum was detected in the sample but in very low composition compared to the amorphous silica that dominat.es the deposits
