Integrating Multicomponent Chemical Geothermometry with Parameter Estimation Computations for Geothermal Exploration

Abstract

A multicomponent chemical geothermometry method developed previously for single point sources was implemented into a computer routine to automatically process water compositions from multiple locations, including correction for dilution and gas loss that can mask or hide the chemical signatures of deep reservoir fluids. The routine was tested at single locations using the comprehensive set of water and gas compositions available for springs and wells at the geothermal system in Dixie Valley, Nevada. The sensitivity of predicted temperatures to the effects of dilution, degassing, and also to input thermodynamic data required for the computations was evaluated. The routine is being tested in conjunction with existing parameter estimation software in an effort to regress data sets from multiple wells and springs simultaneously, to solve for reservoir temperature and at the same time reconstruct the composition of the reservoir fluid. Reactive transport simulations are also being conducted to further assess processes affecting the chemical evolution of deep geothermal fluids as these ascend to ground surface, including mixing, degassing, and water-rock interactions. This integrated approach is expected to allow estimations of reservoir temperatures with better reliability and consistency than currently possible using standard chemical geothermometers.