What is the definition of a probe well? A probe well is a type of well that is used to investigate the nature and extent of underground resources. It is a process of drilling a hollow borehole into the subsurface to gain access to the targeted underground resources. The size and depth of the borehole vary depending on the geological conditions of the area. The purpose of the probe well is to obtain a sample of the materials present in the subsurface. This sample is used to determine the composition and structure of the subsurface and to develop a better understanding of the area. The probe well is also used to identify the various source rocks that are present in the subsurface. These source rocks are important for the extraction of minerals and gases. The probe well also helps to identify the presence of water table, fractures, and other features of the subsurface. This information can be used to determine the best extraction method for obtaining the desired resources.