GeoSys.Chem: Estimate of reservoir fluid characteristics as first step in geochemical modeling of geothermal systems

Abstract

A computer code GeoSys.Chem for the calculation of deep geothermal reservoir fluid characteristics from the measured physical–chemical parameters of separated water and condensed vapor samples obtained from drilled wells is presented. It was written as a dynamic link library (DLL) in Visual Basic in Visual Studio 2010 (VB.NET). Using this library a demonstration program GeoChem was developed in VB.NET, which accepts the input data file in the XML format.A stepwise calculation of deep reservoir fluid characteristics of 11 production wells of Los Azufres geothermal system is performed. The calculated concentration of CO2 (e.g.=1270mmole/kg in the well AZ-09) in the vapor, discharged into the atmosphere at the weir box, from the water sample indicates some problem in the analysis of carbonic species concentrations. In the absence of good quality analysis of carbonic species it is suggested to consider the CO2 in the vapor sample at the separator and the total dissolved carbonic species concentration in the water sample (i.e., without considering the liberation of CO2 in the atmospheric vapor at the weir box) for the geothermal reservoir fluid composition calculations. Similarly, it presents various diagrams developed in Excel for the thermodynamic evolution of Los Azufres geothermal reservoir.