pygeopressure.pressure package

Submodules

pygeopressure.pressure.bowers module

Routines to calculate pore pressure

pygeopressure.pressure.bowers.bowers(v, obp, u, start_idx, a, b, vmax, end_idx=None)[source]

Compute pressure using Bowers equation.

Parameters
  • v (1-d ndarray) – velocity array whose unit is m/s.

  • obp (1-d ndarray) – Overburden pressure whose unit is Pa.

  • v0 (float, optional) – the velocity of unconsolidated regolith whose unit is m/s.

  • a (float, optional) – coefficient a

  • b (float, optional) – coefficient b

Notes

\[P = S - \left[\frac{(V-V_{0})}{a}\right]^{\frac{1}{b}}\]

3

3

Bowers, G. L. (1994). Pore pressure estimation from velocity data: accounting from overpressure mechanisms besides undercompaction: Proceedings of the IADC/SPE drilling conference, Dallas, 1994, (IADC/SPE), 1994, pp 515–530. In International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts (Vol. 31, p. 276). Pergamon.

pygeopressure.pressure.bowers.bowers_varu(v, obp, u, start_idx, a, b, vmax, buf=20, end_idx=None, end_buffer=10)[source]

Bowers Method with buffer zone above unloading zone

Parameters
  • v (1-d ndarray) – velocity array whose unit is m/s.

  • obp (1-d ndarray) – Overburden pressure whose unit is Pa.

  • u (float) – coefficient u

  • start_idx (int) – index of start of fluid expansion

  • a (float, optional) – coefficient a

  • b (float, optional) – coefficient b

  • vmax (float)

  • buf (int, optional) – len of buffer interval, buf should be smaller than start_idx

  • end_idx (int) – end of fluid expasion

  • end_buffer (int) – len of end buffer interval

pygeopressure.pressure.bowers.invert_unloading(v, a, b, u, v_max)[source]

invert of Unloading curve in Bowers’s method.

pygeopressure.pressure.bowers.invert_virgin(v, a, b)[source]

invert of virgin curve.

pygeopressure.pressure.bowers.power_bowers(sigma_vc_ratio, u)[source]
pygeopressure.pressure.bowers.unloading_curve(sigma, a, b, u, v_max)[source]

Unloading curve in Bowers’s method.

pygeopressure.pressure.bowers.virgin_curve(sigma, a, b)[source]

Virgin curve in Bowers’ method.

pygeopressure.pressure.bowers_seis module

pygeopressure.pressure.eaton module

Routines for eaton pressure prediction

Created on Sep 20 2018

pygeopressure.pressure.eaton.eaton(v, vn, hydrostatic, lithostatic, n=3)[source]

Compute pore pressure using Eaton equation.

Parameters
  • v (1-d ndarray) – velocity array whose unit is m/s.

  • vn (1-d ndarray) – normal velocity array whose unit is m/s.

  • hydrostatic (1-d ndarray) – hydrostatic pressure in mPa

  • lithostatic (1-d ndarray) – Overburden pressure whose unit is mPa.

  • v0 (float, optional) – the velocity of unconsolidated regolith whose unit is ft/s.

  • n (float, optional) – eaton exponent

Returns

Return type

ndarray

Notes

\[P = S - {\sigma}_{n}\left(\frac{V}{V_{n}}\right)^{n}\]

4

4

Eaton, B. A., & others. (1975). The equation for geopressure prediction from well logs. In Fall Meeting of the Society of Petroleum Engineers of AIME. Society of Petroleum Engineers.

pygeopressure.pressure.eaton.power_eaton(v_ratio, n)[source]

Notes

\[\frac{\sigma}{{\sigma}_{n}}= \left(\frac{V}{V_{n}}\right)^{n}\]
pygeopressure.pressure.eaton.sigma_eaton(es_norm, v_ratio, n)[source]

calculate effective pressure with the ratio of velocity and normal velocity

Notes

\[{\sigma}={\sigma}_{n}\left(\frac{V}{V_{n}}\right)^{n}\]

pygeopressure.pressure.eaton_seis module

pygeopressure.pressure.hydrostatic module

Function to calculate hydrostatic pressure

Created on Fri Nov 11 2016

pygeopressure.pressure.hydrostatic.hydrostatic_pressure(depth, kelly_bushing=0, depth_w=0, rho_f=1.0, rho_w=1.0)[source]
Parameters
  • depth (scalar or 1-d ndarray) – measured depth, unit: meter

  • rho_f (scalar) – density of pore fluid, g/cm3

  • kelly_bushing (scalar) – kelly bushing elevation, in meter

  • depth_w (scalar) – sea water depth

  • rho_w (scalar) – sea water density

Returns

pressure – unit: mPa

Return type

scalar or 1-d ndarray

pygeopressure.pressure.hydrostatic.hydrostatic_trace(depth, rho=1.01, g=9.8, shift=0)[source]
pygeopressure.pressure.hydrostatic.hydrostatic_well(depth, kb=0, wd=0, rho_f=1.0, rho_w=1.0)[source]
Returns

Hydrostatic pressure as a Log

Return type

Log

pygeopressure.pressure.multivariate module

Routines for multivariate pressure prediction

Created on Sep 20 2018

pygeopressure.pressure.multivariate.effective_stress_multivariate(vel, phi, vsh, a_0, a_1, a_2, a_3, B, U, vmax, start_idx, end_idx=None)[source]
pygeopressure.pressure.multivariate.effective_stress_multivariate_varu(vel, phi, vsh, a_0, a_1, a_2, a_3, B, U, vmax, start_idx, buf=20, end_idx=None, end_buffer=10)[source]
pygeopressure.pressure.multivariate.invert_multivariate_unloading(vel, phi, vsh, a_0, a_1, a_2, a_3, B, U, vmax)[source]

Calculate effective stress using multivariate unloading curve

pygeopressure.pressure.multivariate.invert_multivariate_virgin(vel, phi, vsh, a_0, a_1, a_2, a_3, B)[source]

Calculate effective stress using multivariate virgin curve

Parameters
  • vel (1-d ndarray) – velocity array whose unit is m/s.

  • phi (1-d ndarray) – porosity array

  • vsh (1-d ndarray) – shale volume

  • a_0, a_1, a_2, a_3 (scalar) – coefficients

Returns

sigma

Return type

1-d ndarray

pygeopressure.pressure.multivariate.multivariate_unloading(sigma, phi, vsh, a_0, a_1, a_2, a_3, B, U, vmax)[source]

Calculate velocity using multivariate unloading curve

pygeopressure.pressure.multivariate.multivariate_virgin(sigma, phi, vsh, a_0, a_1, a_2, a_3, B)[source]

Calculate velocity using multivariate virgin curve

Parameters
  • sigma (1-d ndarray) – effective pressure

  • phi (1-d ndarray) – effective porosity

  • vsh (1-d ndarray) – shale volume

  • a_0, a_1, a_2, a_3 (float) – coefficients of equation

  • B (float) – effective pressure exponential

Returns

out – velocity array

Return type

1-d ndarray

Notes

\[V = a_0 + a_1\phi + a_2{V}_{sh} + a_3 {\sigma}^{B}\]

5

5

Sayers, C., Smit, T., van Eden, C., Wervelman, R., Bachmann, B., Fitts, T., et al. (2003). Use of reflection tomography to predict pore pressure in overpressured reservoir sands. In submitted for presentation at the SEG 2003 annual meeting.

pygeopressure.pressure.multivariate.pressure_multivariate(obp, vel, phi, vsh, a_0, a_1, a_2, a_3, B, U, vmax, start_idx, end_idx=None)[source]

Pressure Prediction using multivariate model

pygeopressure.pressure.multivariate.pressure_multivariate_varu(obp, vel, phi, vsh, a_0, a_1, a_2, a_3, B, U, vmax, start_idx, buf=20, end_idx=None, end_buffer=10)[source]

Pressure Prediction using multivariate model

pygeopressure.pressure.obp module

pygeopressure.pressure.utils module

Module contents