| Title | Dissolution Kinetics of Quartz and Granite in Acidic and Basic Salt Solutions |
|---|---|
| Authors | W. Gabriel Worley and Jefferson W. Tester |
| Year | 1995 |
| Conference | World Geothermal Congress |
| Keywords | dissolution kinetics, rock-water interactions, hot dry rocks |
| Abstract | Of importance to Hot Dry Rock (HDR) geothermal energy development is the characterization of the rate of dissolution of host reservoir rock as a function of temperature, pressure, and liquid phase composition. Experiments were carried out in a continuous-flow titanium spinning basket reactor from 100í to Nitric acid solutions down to 1.1 showed very little effect on the quartz dissolution rate. The effect of hydroxide ion concentration and ionic strength were evaluated in pure NaOH, and solutions. The fractional order dependency of the quartz dissolution rate on hydroxide ion and sodium ion (or ionic strength) concentration were determined in solutions. Quartz dissolution rates were slower in solutions than in NaOWNaCl solutions at sodium concentrations higher than 0.01 molal. The apparent activation energy from 100í to 200?C in deionized water to NaOWNaCl solutions up to 0.01 molal hydroxide ion and 0.1 molal sodium ion was estimated to be 83 Granite dissolution experiments at were also performed to provide a more realistic model of typical reservoir rock found in HDR systems. The dissolution rate of albite and quartz in granite were estimated to be one to two orders of magnitude faster than individual dissolution rates. |