Archie's law
From Wikipedia, the free encyclopedia
In petrophysics Archie's law relates the in-situ electrical conductivity of sedimentary rock to its porosity and brine saturation:
- Ct = Cw Φm Swn
Here, Φ denotes the porosity, Ct the electrical conductivity of the fluid saturated rock, Cw represents the electrical conductivity of the brine, m is the cementation exponent of the rock (usually in the range 1.8 - 2.0), and n is the saturation exponent (usually close to m).
Archie's law is named after Gus Archie (1907 - 1978) who developed this empirical quantitative relationship between porosity, electrical conductivity, and brine saturation of rocks. Archie's law laid the foundation for modern well log interpretation as it relates borehole electrical conductivity measurements to hydrocarbon saturations (which, for fluid saturated rock, equals 1 - Sw).
[edit] Reference
- G. Archie: "The Electrical Resistivity Log as an Aid in Determining Some Reservoir Characteristics" (Transactions of AIME, 1942).
