Comparison of Solute and Multicomponent Geothermometry: a Study Case of Mount Rajabasa Geothermal Field

Abstract

Geothermometry has always been a preferred method to estimate reservoir temperature in a relatively quick process at minimum cost. Among several types of geothermometry, solute geothermometry is the most common to be used due to its relatively uncomplicated calculation. However, it often involves high uncertainties thus the estimated temperature is occasionally rather inaccurate. This research aims at applying a new statistical approach to geothermometry to yield a more reliable reservoir temperature estimation. The new approach is called multicomponent geothermometry. This method uses the iGeoT code with a simple automatization for estimating unknown or poorly unknown constrained parameters. This method is applied to the Mount Rajabasa Geothermal Field in Lampung Province, Indonesia, and later validated against reservoir temperature from solute geothermometry. Results indicate both methods yield similar values close to 260°. Despite the similarity, multicomponent geothermometry is believed to offer better quality results since it takes into consideration of full chemical analysis and mineral saturation indices to obtain optimization. The application of multicomponent geothermometry jointly with solute geothermometry in the research area has proved to significantly increase accuracy and reliability in estimating reservoir temperature. The methods presented in this research may be advantageous for easy-to-handle analysis of other geothermal fields with standard geochemical data without the need for a sophisticated analysis yet earning more accurate results.