Redirected from Magnetic permeability
where B is the magnetic flux density (also called the magnetic induction) in the material and H is the magnetic field strength.
In SI units, magnetic flux density is measured in tesla, magnetic field strength in ampere per metre and permeability in henrys per metre.
Relative permeability, sometimes denoted by the symbol μr and often simply by μ, is the ratio of the absolute permeability to the permeability of free space μ0.
For a rock to be considered as an exploitable hydrocarbon reservoir, its permeability must be greater than approximately 100 md (depending on the nature of the hydrocarbon - gas reservoirs with lower permeabilities are still exploitable because of the lower viscosity of gas with respect to oil). Rocks with permeabilities significantly lower than 100 md can form efficient seals (see petroleum geology). Unconsolidated sands may have permeabilities of 5000+ md.
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