ABSTRACT
Geothermal waters exhibit a broad range of chemical compositions (Tables 5.1 and 5.2), from very dilute (a few hundred parts per million, by weight, of total dissolved constituents) to very concentrated (solutions containing tens of percent, by weight, of dissolved constituents). This dissolved load can provide important information about the characteristics of a reservoir including its temperature, mineralogy, and history. However, the dissolved load can also impact the performance of machinery in a geothermal power plant, or in direct use or heating and cooling applications. This chapter considers the basic chemical processes that influence the chemical properties of geothermal fluids, and how to utilize chemical analyses to gain information about the geothermal resource. Later, in Chapters 6 and 7, we will apply these principles to evaluate specific aspects of geothermal resources. In Chapter 12 we will consider how the chemical composition of geothermal fluids can, in some instances, be mitigated.
