Geomechanics and FracturingIn-Situ Stress and Rock Mechanics

Compressional and Shear Wave Velocities from Elastic Moduli Formula

V_p=\sqrt{\frac{K+4G/3}{\rho}}

Compressional and Shear Wave Velocities from Elastic Moduli calculates compressional wave velocity for in-situ stress and rock mechanics workflows in geomechanics and fracturing.

Calculate

How engineers use this formula

Use this formula when the listed inputs (K, G, rho) are known and the assumptions behind the cited in-situ stress and rock mechanics 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, V_p equals 244.948974 velocity.

Kpsi

5000000

Gpsi

3000000

rhomass/volume

150

Inputs

K

psi

Bulk Modulus

G

psi

Shear Modulus

rho

mass/volume

Density

Outputs

V_p

velocity

Compressional Wave Velocity

V_s

velocity

Shear Wave Velocity

Source and review

reviewed

Reservoir Geomechanics, Zoback, M.D. (2007)

Zoback, M.D. 2007. Reservoir Geomechanics. Cambridge University Press, Page 63.

Source