Geophysics is commonly used to map groundwater and find aquifers. Geophysical techniques most often used in groundwater investigations include seismic refraction, time domain electromagnetics, gravity, and resistivity profiling. Seismic refraction determines the depth to the water table and the depth to hard bedrock. Resistivity soundings are used to determine the clay content of the aquifer. Combining these techniques finds the best locations for drilling.
After a well is drilled, borehole geophysics maps the geologic layers the well penetrated. Geophysical well logs help determine the best screen intervals for production. Surface and borehole geophysics result in more productive wells and lower drilling costs.