Philippine E-Journals

 pH Buffering for Acidic Geothermal Wells Utilization

Yolanda P. Brondial | Azucena A. Puertollano

Discipline: Engineering, Chemistry

 

Abstract:

The current practice of plugging corrosive wells (low-pH or acidic) and, consequently, abandoning them could incur huge financial losses to the geothermal industry in terms of costs of drilling and of well tests. A potential method For commercializing high-enthalpy acidic geothermal wells was explored by raising the pH of geof1uids to ,2 3.5, pH levels considered by geothermal reservoir engineers to be non-corrosive to low-carbon steel. ALBER and YODIN, two new bufFer solutions of chlorinated carboxylic acids and their sodium salts, were used for the laboratory tests. A predetermined volume of each buffer was mixed with a large amount of acidic geothermal brine. A geof1uid to buffer volume ratio of as high as 200 at 10crC using an initial geof1uid pH of as low as 1.94 could raise the brine pH to the desired value 3.5 or greater. The amount of buffer was observed to depend on its pH and concentration before addition to the brine and on the stability of the geofluid pH. The higher the temperature of operation, the higher was the geofluid buffer volume ratio attained due to the low solubility of the acid-forming gases (C02 and H2S) present in the geofluid.