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Predicting the Buffering Effectiveness of Alber Solutions by Dimensional Analysis


During acidizing of geothermal wells, the geofluid becomes so acidic as to cause corrosion in low carbon steel pipes, casings, and wellheads, a serious phenomenon that leads to the plugging and abandonment of these wells. In order to recover the drilling costs and offset the concomitant losses, laboratory and bench-scale experiments were undertaken to increase the geofluids to pH values > 3.5 by adding ALBER buffering solutions: a mixture of monochloroacetic acids and their sodium salts. From years of experience in geothermal operations, engineer specialists have found these pH levels to be non-corrosive to low-carbon steel. The laboratory-scale results showed that brine pH > 3.5 could be obtained at 100°C for as low an initial geofluid pH of 1.9, an initial ALBER pH as low as 3.5, an ALBER concentrations as low as 0.35M, and a geofluid/ALBER volume ratio as high as 175. The bench-scale simulations employed higher initial average geofluid pH of 2.5, initial average ALBER pH of 3.45, average ALBER solution temperature of 75°C and at constant ALBER concentration of 0.25 M. Simulations were performed for mass flow rates of ALBER solution at 2.5 gm/sec and 5.0 gm/sec and into columns, 1.5-inch 1.D and 2.0-inch 1.D. The pH of geofluid mixture > 3.5 was attainable in the latter experiments at a mass flow rate of ALBER solution = 5 gm/sec in each of the two columns, 1.5-inch and 2.5-inch diameter, respectively.

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