Effects of Silica Polymization on Apparent Viscosity of Geothermal Water - Fundamental Study on Precipitation of Silica Scale -

Research Project

Project/Area Number	62550456
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	資源開発工学
Research Institution	TOHOKU UNIVERSITY
Principal Investigator	CHIDA Tadashi Faculty of Engineering, Tohoku Univ., 工学部, 教授 (10005499)
Co-Investigator(Kenkyū-buntansha)	NIIBORI Yuuichi Faculty of Engineering, Tohoku Univ., 工学部, 助手 (90180562)
Project Period (FY)	1987 – 1988
Project Status	Completed (Fiscal Year 1988)
Budget Amount *help	¥2,000,000 (Direct Cost: ¥2,000,000) Fiscal Year 1988: ¥400,000 (Direct Cost: ¥400,000) Fiscal Year 1987: ¥1,600,000 (Direct Cost: ¥1,600,000)
Keywords	Rate of silica polymization / Apparent viscosity / Silica deposition / Precipitation of silica / Decrease of permeability / Soluble silica / Polysilicic acid / 全ケイ酸濃度 / シリカ / 貯留層の透水性低下 / シリカの沈澱 / モリブデン黄吸光光度法 / スケール付着量 / 見掛け粘度 / 炭素綱板 / 回転粘度計
Research Abstract	This study discussed on (1) the rate of silica polymerization, (2) the relation between the apparent viscosity and the deposition to carbon steel and (3) the decrease of permeability caused by the precipitaion of silica. The conclusions are as follow: (1) The rate of decrease in soluble silica concentration is proportional to the surface area of polysilicic acid and the twice power of the oversatulated soluble silica concentration, when the experimental conditions are under pH8-9, temperature 30-50゜C, NaCl concentration 0 mol dm^<-3>, initial soluble silica conc. about 520ppm and total silica conc. about 570ppm. (2) As the apparent viscosity of solution increases, the quantity of silica deposition to carbon steel increases. Also as the precipitation is generated, the apparent viscosity of solution increaes rapidly. Then, the experiments conditions are; ph8-9, temp. 30゜C, NaCl conc. 0-1mol dmD1-3@>D1, initial soluble 250-1500ppm. (3) The effects of silica precipitation to the decrease of permeability depend on the particle diameter, when the experiments are carried out by using packed bed with glass beads. In the case of 0.3mm diameter beads, the permeability decreases generally. On the other hand, in the use of 1mm diameter beads, recovery of the permeability after the rapid decrease.