Fluid Geochemistry Applications in Reservoir Engineering (Vapor-Dominated System)

Abstract

During these last few years fluid geochemistry has proved to be a valid tool for analysing the processes occurring in geothermal reservoirs. Space and time variations in fluid composition have been interpreted as being due to geological setting and reservoir processes, including water recharge, steam condensation and vaporization of liquid water. The major effort is now invested in developing conceptual and quantitative models for chemical and physical processes that could produce the observed variations in fluid composition. These models are an effective complement to the classical methods of reservoir engineering in field development and exploitation. The fields in which the geochemical methods seem to be most effective are: individuation of the main zones of steam upflow and of fluid sources in the various parts of the reservoir; identification of the main flow paths of the fluid in the reservoir; geothermometry; estimates of liquid saturation of the reservoir; analysis of the processes of natural recharge and reinjection. Previous work in the field, as well as current development of research conducted by the authors on gas composition, are discussed and reviewed.