Permeability Converter
Instantly convert permeability with our free converter. See conversion tables, formulas, and step-by-step explanations.
Formula
Converted = Input x (From Unit in m2) / (To Unit in m2)
Each permeability unit maps to a value in square meters. One darcy = 9.869233e-13 m2. One millidarcy = 9.869233e-16 m2. Convert by multiplying the input by the source unit factor, then dividing by the target unit factor.
Worked Examples
Example 1: Converting Darcies to Millidarcies
Problem: A rock sample has a permeability of 0.5 darcies. Express this in millidarcies and square meters.
Solution: Millidarcies = 0.5 D x 1000 = 500 mD\nSquare meters = 0.5 x 9.869233e-13 = 4.9346e-13 m2
Result: 0.5 D = 500 mD = 4.9346e-13 m2
Example 2: Reservoir Rock Permeability
Problem: A reservoir has 250 millidarcies permeability. Convert to darcies and square micrometers.
Solution: Darcies = 250 / 1000 = 0.25 D\nSquare meters = 250 x 9.869233e-16 = 2.4673e-13 m2\nSquare micrometers = 2.4673e-13 / 1e-12 = 0.2467 um2
Result: 250 mD = 0.25 D = 0.2467 um2
Frequently Asked Questions
What is permeability and how is it measured?
Permeability is a measure of how easily fluids can flow through a porous material such as rock, soil, or a filter. It is measured in units of area, with the darcy being the most common unit in petroleum engineering and geology. One darcy represents a relatively high permeability. Most reservoir rocks have permeabilities measured in millidarcies. The SI unit for permeability is square meters, but darcies are far more practical for real-world geological measurements.
What are typical permeability values for common materials?
Permeability varies enormously across different materials. Clean gravel has permeability of 10,000 to 100,000 darcies. Clean sand ranges from 1 to 1,000 darcies. Good oil reservoir rock typically measures 100 to 1,000 millidarcies. Tight sandstone falls between 0.01 and 1 millidarcy. Shale can be as low as 0.000001 millidarcies (nanodarcies). Granite and other unfractured crystalline rocks have permeabilities near zero, making them excellent barriers for groundwater containment.
How does permeability differ from porosity?
Porosity measures the fraction of void space in a material (expressed as a percentage), while permeability measures how interconnected those voids are and how easily fluid can flow through them. A material can have high porosity but low permeability if the pores are not well connected, such as pumice stone which has many air pockets but poor fluid transmission. Conversely, fractured rock may have low porosity but high permeability along the fractures. Both properties are essential for characterizing reservoir rocks in petroleum and groundwater engineering.
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