A core is an undisturbed sample that has been retrieved from the earth's surface, sub-surface, or underneath the earth's surface, commonly called a reservoir. Cores are obtained by drilling an oil or gas well with a diamond drill bit. Core Analysis is the study of the petrophysical properties of the core to determine its oil, water and hydrocarbon saturation. Routine and Special Core analysis includes a series of laboratory tests and analysis carried out to predict the efficiency estimation of a given well. These tests includes wettability, resistivity, formation factor, porosity, permeability, resistivity index and fluid saturation performed on plug samples cut from the core.