How to Use Porosity & Permeability Calculator
The Porosity & Permeability Calculator handles two separate but related calculations: void-fraction (porosity) from simple volume measurements, and intrinsic permeability from a laboratory Darcy-flow experiment.
- Porosity mode — enter pore volume V_p (measured by saturation, gas expansion or mercury injection) and total bulk volume V; the tool returns Φ as a decimal and a percentage.
- Permeability mode — set up a constant-head permeameter; measure steady-state flow rate Q through cross-section A over sample length L under pressure drop ΔP.
- Enter fluid viscosity μ — for water at 20 °C use 1.002 × 10⁻³ Pa·s; for in-situ brine or oil, use the reservoir-condition value.
- Read intrinsic permeability k in m² and the automatically converted value in millidarcy (mD) — the standard unit in petroleum engineering.
- Check internal consistency — the result panel shows a Kozeny–Carman indicative permeability from Φ for comparison with the measured k.
Formula & Theory — Porosity & Permeability Calculator
The Porosity & Permeability Calculator combines the volumetric porosity definition with Darcy’s macroscopic flow law:
Φ = V_p / V (porosity)
k = Q · μ · L / (A · ΔP) (Darcy's law)
k_mD = k / 9.869233 × 10⁻¹⁶ (m² to millidarcy)| Symbol | Meaning | SI Unit |
|---|---|---|
| Φ | Porosity (void fraction) | — |
| V_p | Pore (void) volume | m³ |
| V | Total (bulk) volume | m³ |
| k | Intrinsic permeability | m² |
| Q | Volumetric flow rate through sample | m³/s |
| μ | Dynamic fluid viscosity | Pa·s |
| L | Sample length in flow direction | m |
| A | Cross-section area perpendicular to flow | m² |
| ΔP | Applied pressure difference | Pa |
Typical permeability ranges: gravel 10⁴–10⁵ mD, clean sand 10²–10³ mD, sandstone reservoir 10–500 mD, tight gas sand < 0.1 mD, shale 10⁻⁶–10⁻³ mD. Typical porosity: unconsolidated sand 30–40 %, sandstone 5–30 %, limestone 5–20 %, granite < 2 %.
Use Cases for Porosity & Permeability Calculator
- Petroleum reservoir characterisation — interpret core-plug laboratory measurements to estimate in-situ producibility, drainage rate and completion interval selection.
- Hydrogeology and aquifer testing — convert falling-head permeameter or slug-test data to hydraulic conductivity for groundwater flow and solute transport modelling.
- Civil engineering filter design — verify that filter and drainage layer materials meet permeability specifications to prevent piping failure under dams and levees.
- Environmental site assessment — quantify contaminant migration rates through saturated and unsaturated zones to plan remediation pumping or barrier systems.
- Building material science — measure moisture transport permeability of concrete, masonry, insulation and membranes for durability and building-energy model inputs.
- Academic rock physics — pair Φ and k measurements with seismic velocity data to calibrate digital-rock simulations and constitutive model parameters.