Logging
A log is defined as a systematic record of data. In the oil field, logging refers to the process of recording formation information downhole for evaluating properties and reservoir characteristics. A well log is a plot of different formation properties versus depth. Interpretation of well logs can help identify lithologies, porosity, permeability, etc and provide valuable information in identifying a pay zone. Various different types of tools are run in the well on either wireline or drill pipe to measure different formation properties. Logging tools use electrical, electronic, sonic, and radioactive materials to be able to measure specific rock properties.