Pressure Drops Due to Silica Scaling

Abstract

Experience with reinjection returns in many geothermal fields has prompted a move towards injecting waste fluids at some distance from the production field. This means that often, reinjection pipelines cover very long distances. If the waste water in the pipelines is supersaturated with respect to amorphous silica. then the deposition of silica these pipelines is almost certain. Although the deposit may be of negligble the inner surface characteristics of the pipe will be different to those of clean mild steel.

During a silica scaling experiment. geothermal brine was passed through a series of pipes of different sizes and over a period of three weeks, silica scale formed on the surface. The pressure drop along a distance of approximately 5m was measured by a water manometer in all test pipe sections. Significant pressure drop was observed during this time and can be correlated with the increase in the friction factor of pipe walls due to silica scaling.