Optimization of Silica Chemical Inhibition Using Phosphinocarboxylic Acid Copolymer Through Nanocolloidal Particle Size Measurement of Simulated Geothermal Fluid

Abstract

Chemical inhibition is the primary preventive option to minimize silica scaling in the geothermal well and pipe lines, aside from the regular monitoring of the silica saturation indices. Effective application of inhibitors has been discussed in several studies, but the mechanism and/or action on the fluid have not been thoroughly classified. Field testing thru pilot or actual set-up is the primary conclusive test of effectivity, done by measurement of molybdate-reactive silica levels, and/or calculation of deposition rate after actual inspection. Several field studies in the Energy Development Corporation (EDC) affirmed the capability of a chemical inhibitor, phosphinocarboxylic acid copolymer, in terms of suppressing the deposition rate of silica scale in both high and low temperature applications. Advanced particle size evaluation thru the use of atomic force microscopy (AFM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were appended to identify the optimal dosage of the phosphinocarboxylic acid inhibitor in addition to standard silicomolybdate analysis on a simulated geothermal fluid at the laboratory scale. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to confirm the formation of the amorphous silica solution from simulated brine solution.