| Abstract |
As a severe production issue in Dieng geothermal field, silica scaling has been a major threat in various hydrothermal field dominated with water, thus affecting severely on production and electricity generation of the field. To overcome the damaging effect of silica scaling, an innovative and suitable fluid injection management is a must. This research is conducted by gathering geothermal field data from previously observed fields and comprehensive data analysis in order to achieve the best possible solution. The amount of silica deposition is estimated by calculating the difference between dissolved SiO2 with the solubility of amorphous silica curve. At 180°C and 160°C, the induction time for polymerization was not reached. Scaling rates were 0.2 to 0.3 mm/yr at 180°C (assuming density 2.2), increasing to 0.3 to 0.4 mm/yr at 160°C. At 140°C and 120°C, there was measurable polymer formation, even at the pipe inlet, and the polymer concentration increased through the pipeline; the increase at 120°C was twice that at 140°C. Therefore, scaling in the pipeline decreased dramatically along the length of the pipe, as monomeric SiO2 was removed from solution into the suspended polymer. In all cases, the scale which formed was hard and glassy, with density about 2 gm/ cc. Accordingly, researchers found that the deposition process of silica scaling in Dieng Geothermal Field highly depends on temperature and fluid pH. With those dependence in mind, it is possible to assume low-level scaling confidently enough for purposes regarding production, injection system and mechanism. This can be achieved by suppression technology with the main purpose is to reduce the pH of the fluid by mixing with non-condensable gases and steam condensate. Improved developments in the future on predictive technique will result in uniformity in data collection and experiment design. |