Reservoir EngineeringPermeability

Gas Permeability from Core Plug Pressure-Squared Flow Formula

k = \frac{2\mu Q_{avg}P_{avg}L}{A(P_1^2-P_2^2)}

Gas Permeability from Core Plug Pressure-Squared Flow calculates gas permeability for permeability workflows in reservoir engineering.

Calculate

How engineers use this formula

Use this formula when the listed inputs (mu, Q_avg, P_avg, L, A, P1, P2) are known and the assumptions behind the cited permeability relationship match the engineering case being checked.

Assumptions

Input values are representative for the well, reservoir, fluid, or equipment case being evaluated.
The declared units match the field-unit constants used in the formula.
The cited formula applies to the selected petroleum engineering workflow.

Limitations

The calculation does not replace a full engineering model or operating procedure.
Accuracy depends on the source correlation, assumptions, input quality, and unit consistency.

Common mistakes

Mixing unit systems without converting the inputs.
Using default example values as field recommendations.
Applying the formula outside the source assumptions.

Default example

Using the default inputs, k equals 0.0225 D.

mucP

0.018

Q_avgcm^3/s

P_avgatm

Lcm

Acm^2

P1atm

P2atm

Inputs

mu

Gas Viscosity

Q_avg

cm^3/s

Average Gas Flow Rate in Core

P_avg

atm

Average Pressure in Core

L

Core Plug Length

A

cm^2

Open-Flow Area of Core Plug

P1

atm

Inlet Pressure

P2

atm

Outlet Pressure

Outputs

k

Gas Permeability

mu