Definition - What does Resistivity mean?
Resistivity is the measurement of fluid conductivity and the formation. Conductivity is the reciprocal of Resistivity. Surveys are carried out in various oil and gas fields and then Resistivity logs prepared are studied. These Resistivity surveys help in creating a three-dimensional structure of the hydrocarbon formation below the surface. This helps in identifying oil and gas reservoirs with high chances of trapped oil and gas in the geological formations.
Petropedia explains Resistivity
Resistivity is one of the important steps performed by geologists before taking any drilling decisions. Resistivity surveys are built and studied in the exploration stage and are basically used for creating a profile to understand the reservoir formation. They indicate the oil zones verses the water zones. Resistivity also helps in estimating the depth in shale rock from where natural gas can be obtained. When a well is drilled, a Resistivity measurement is also done. This helps in defining the water, oil and gas in the pore spaces of the formation traversed by the well. Water saturation can be calculated by the following formula:
Sw = (F x Rw/Rt)^1/2
Where Sw refers to Water saturation
Rw refers to Resistivity
Rt refers to True Resistivity
F refers to Archie formation factor.