Rock physics

Han model

PyFWI.rock_physics.Han(phi, cc, a1=5.5, a2=6.9, a3=2.2, b1=3.4, b2=4.7, b3=1.8)

Han estimates velocity based on porosity and clasy content

Han found empirical regressions relating ultrasonic (laboratory) velocities to porosity and clay content

Parameters:
  • phi ([type]) – [porosity

  • cc ([type]) – clay content

  • a1 (float, optional) – Constant value for Vp. Defaults to 5.77.

  • a2 (float, optional) – Constant value for Vp. Defaults to 6.94.

  • a3 (float, optional) – Constant value for Vp. Defaults to 1.728.

  • b1 (float, optional) – Constant value for Vs. Defaults to 5.77.

  • b2 (float, optional) – Constant value for Vs. Defaults to 6.94.

  • b3 (float, optional) – Constant value for Vs. Defaults to 1.728.

Returns:

P-wave velocity (km/s) vs = S-wave velocity (km/s)

Return type:

vp

References

  1. Hu et al, 2021, Direct updating of rock-physics properties using elastice full-waveform inversion

  2. Mavko, G., Mukerji, T., & Dvorkin, J., 2020, The rock physics handbook. Cambridge university press.

Drained K and μ

PyFWI.rock_physics.drained_moduli(phi, k_s, g_s, cs)

drained_moduli computes the effective mechanical moduli KD and GD

[extended_summary]

Parameters:
  • phi (float) – Porosity

  • k_s (float) – Solid bulk modulus

  • g_s (float) – Solid shear modulus

  • cs (float) – general consolidation parameter

Returns:

  • k_d (float) – Effective drained bulk modulus

  • g_d (float) – Effective drained shear modulus

References

Dupuy et al., 2016, Estimation of rock physics properties from seismic attributes — Part 1: Strategy and sensitivity analysis, Geophysics

Voigt Berie

Biot-Gassmann model

Weighted averaging

PyFWI.rock_physics.weighted_average(prop1, prop2, volume1)

weighted_average is a function to calculate the wighted average of properties

Parameters:
  • prop1 (float) – Property of the material 1

  • prop2 (float) – Property of the material 2

  • volume1 (float) – Value specifying the rational volume of the material 1

Returns:

mixed – Property of mixed material

Return type:

float

Switch lmd to vd

PyFWI.rock_physics.lmd2vd(lam, mu, rho)

lmd2vd switches Lama modulus and density to vp, vs, density

[extended_summary]

Parameters:
  • lam ([type]) – [description]

  • mu ([type]) – [description]

  • rho ([type]) – [description]

Returns:

[description]

Return type:

[type]

Switch vd to lmd

PyFWI.rock_physics.vd2lmd(vp, vs, rho)

vd2lmd switches vp, vs, density to Lame modulus and density to

[extended_summary]

Parameters:
  • vp ([type]) – [description]

  • vs ([type]) – [description]

  • rho ([type]) – [description]

Returns:

[description]

Return type:

[type]