(pur mē ∂ bil’ i tē)
1. The ratio of the magnetic field B to the magnetizing force H.
2. A measure of the ease with which a fluid can pass through the pore spaces of a formation. Measured in millidarcy (1/1000 darcy) units. The permeability constant k is expressed by Darcy’s law as μq/(d'p'/dx), where μ is fluid viscosity, q is linear rate of flow, and d'p'/dx is the hydraulic pressure gradient. The presence of one fluid can change the effective permeability to another fluid, so that in multiphase flow the effective permeabilities of the component fluids may not add to the total permeability. See Figure P-1.