Geophysical methods of well investigation are aimed at studying the geological section and, in particular, identifying layers of different lithology, determining their angles and azimuths of dip, identifying minerals in the sections, as well as evaluating the porosity, permeability, reservoir properties of surrounding rocks, and their possible oil and gas productivity. Special equipment is used to control the technical condition of wells (determination of their diameters, curvatures, presence of cement in the annulus, etc.). The same fields and methods used in field geophysics are applied in well investigations.
The effectiveness of well geophysics is very high, especially in petroleum and structural geology, where drilling of all wells is accompanied by geophysical surveys. They are widely used in the search for mineral deposits. In engineering and hydrogeological investigations, well geophysical methods are used to study porosity, water saturation, filtration properties of rocks, and, along with core sampling, geological documentation of sections is carried out.