The Use of Amino G as a Thermally Reactive Tracer for Geothermal Applications

Abstract

A thermally reactive tracer can be used in combination with a conservative tracer within a geothermal reservoir to determine the effective temperature along an injection-production pathway. The thermal decay kinetics of the uv-fluorescent optical brightener 7-amino-1,3-naphthalenedisulfonate (Amino G) was measured under simulated geothermal conditions using a high-temperature laboratory batch reactor. The decay product was shown to be a fluorescent, water-soluble compound possessing greater thermal stability than the parent compound. Amino G and its daughter product thus represent a new tracer pair for use in geothermal reservoirs, suggesting that other amino-substituted or even hydroxy-substituted naphthalene sulfonates might be used as geothermal tracers. A tracer test demonstrated the successful use of Amino G at the Dixie Valley geothermal field.