Geothermal Exploration Methods

A geothermal reservoir causes inhomogeneity in the physical properties of the subsurface geology due to the high changes in temperature. These physical properties can be ob‐ served by means of varying anomalies from geophysical observations from the surface. These physical properties include electrical conductivity, rock density, magnetic suscepti‐ bility, rock elasticity, and, finally, the temperature. The above mentioned physical prop‐ erties can be detected by surficial geophysical survey. The same parameters can also be measured in wells using “geophysical well logging,” providing data that are more accu‐ rate but costly. On the other hand, geochemical exploration assists in gathering informa‐ tion about the subsurface composition of the fluids. This information can be used indirectly to know the temperature, origin, and flow direction, which help in locating subsurface geothermal reservoir. It is clear that, from geophysical and geochemical meth‐ ods, shape, size, structure, depth, and heat sources of the reservoir can be traced and mapped. Thus, the geophysical and geochemical surveys play a key role in geothermal exploration. This chapter will discuss the above mentioned methods in detail presenting some examples from literature review.