bruges.petrophysics package#
Submodules#
bruges.petrophysics.petrophysics module#
- bruges.petrophysics.petrophysics.density_to_porosity(rho, rho_matrix, rho_fluid)[source]#
Get density from a porosity log. Typical values:
rho_matrix (sandstone) : 2650 kg/m^3
rho_matrix (limestome): 2710 kg/m^3
rho_matrix (dolomite): 2876 kg/m^3
rho_matrix (anyhydrite): 2977 kg/m^3
rho_matrix (salt): 20320 kg/m^3
rho_fluid (fresh water): 1000 kg/m^3
rho_fluid (salt water): 1100 kg/m^3
See wiki.aapg.org/Density-neutron_log_porosity.
- Parameters
rho (ndarray) – The bulk density log or RHOB.
rho_matrix (float) –
rho_fluid (float) –
- Returns
Estimate of porosity as a volume fraction.
- bruges.petrophysics.petrophysics.density_to_velocity(rho, alpha=310, beta=0.25, fps=False)#
Computes Gardner’s density prediction from P-wave velocity.
- Parameters
rho (ndarray) – Density in kg/m^3.
alpha (float) – The factor, 310 for m/s and 230 for fps.
beta (float) – The exponent, usually 0.25.
fps (bool) – Set to true for FPS and the equation will use the typical value for alpha. Overrides value for alpha, so if you want to use your own alpha, regardless of units, set this to False.
- Returns
Vp estimate in m/s.
- Return type
ndarray
- bruges.petrophysics.petrophysics.error_flag(pred, actual, dev=1.0, method=1)[source]#
Calculate the difference between a predicted and an actual curve and return a log flagging large differences based on a user-defined distance (in standard deviation units) from the mean difference
Matteo Niccoli, October 2018
- Parameters
predicted (ndarray) –
actual (ndarray) –
dev (float) –
method (error calcluation) – 1: difference between curves larger than mean difference plus dev 2: curve slopes have opposite sign 3: curve slopes of opposite sign OR difference larger than mean plus dev
Returns: flag (ndarray) = error flag curve
- bruges.petrophysics.petrophysics.gardner(vp, alpha=310, beta=0.25, fps=False)[source]#
Computes Gardner’s density prediction from P-wave velocity.
- Parameters
vp (ndarray) – P-wave velocity in m/s.
alpha (float) – The factor, 310 for m/s and 230 for ft/s.
beta (float) – The exponent, usually 0.25.
fps (bool) – Set to true for FPS and the equation will use the typical value for alpha. Overrides value for alpha, so if you want to use you own alpha, regardless of units, set this to False.
- Returns
RHOB estimate in \(kg/m^3\).
- Return type
ndarray
- bruges.petrophysics.petrophysics.gardner_param(vp, rhob)[source]#
Finds optimal alpha and beta parameters for the gardner
Volodymyr Vragov, October 2018
- Parameters
rho (ndarray) – Density.
vp (ndarray) – P-wave velocity.
- Returns
The factor. beta (float): The exponent, usually 0.25.
- Return type
alpha (float)
- bruges.petrophysics.petrophysics.inverse_gardner(rho, alpha=310, beta=0.25, fps=False)[source]#
Computes Gardner’s density prediction from P-wave velocity.
- Parameters
rho (ndarray) – Density in kg/m^3.
alpha (float) – The factor, 310 for m/s and 230 for fps.
beta (float) – The exponent, usually 0.25.
fps (bool) – Set to true for FPS and the equation will use the typical value for alpha. Overrides value for alpha, so if you want to use your own alpha, regardless of units, set this to False.
- Returns
Vp estimate in m/s.
- Return type
ndarray
- bruges.petrophysics.petrophysics.optimize_inverse_gardner(rho, alpha, beta)[source]#
Wrapper function to pass inverse_gardner to scipy.curve_fit to get optimal alpha and beta parameters
Matteo Niccoli and Volodymyr Vragov, October 2018
- Parameters
rho (ndarray) – Density.
alpha (float) – The factor.
beta (float) – The exponent.
- Returns
this is passed to scipy.curve_fit as, for example: popt_synt, pcov = scipy.curve_fit(optimize_inverse_gardner, rho, vp) For a full example, please read: mycarta.wordpress.com/2018/10/28/geophysics-python-sprint-2018-day-2-and-beyond-part-i
- Return type
inverse_gardner
- bruges.petrophysics.petrophysics.porosity_to_density(phi, rho_matrix, rho_fluid)[source]#
Get density from a porosity log. Typical values:
rho_matrix (sandstone) : 2650 kg/m^3
rho_matrix (limestome): 2710 kg/m^3
rho_matrix (dolomite): 2876 kg/m^3
rho_matrix (anyhydrite): 2977 kg/m^3
rho_matrix (salt): 20320 kg/m^3
rho_fluid (fresh water): 1000 kg/m^3
rho_fluid (salt water): 1100 kg/m^3
See wiki.aapg.org/Density-neutron_log_porosity.
- Parameters
phi (ndarray) – The porosity log.
rho_matrix (float) –
rho_fluid (float) –
- Returns
Estimate of bulk density, rho.
- bruges.petrophysics.petrophysics.slowness_to_velocity(slowness)[source]#
Convert a slowness log in µs per unit depth, to velocity in unit depth per second.
- Parameters
slowness (ndarray) – A value or sequence of values.
- Returns
The velocity.
- Return type
ndarray
- bruges.petrophysics.petrophysics.velocity_to_density(vp, alpha=310, beta=0.25, fps=False)#
Computes Gardner’s density prediction from P-wave velocity.
- Parameters
vp (ndarray) – P-wave velocity in m/s.
alpha (float) – The factor, 310 for m/s and 230 for ft/s.
beta (float) – The exponent, usually 0.25.
fps (bool) – Set to true for FPS and the equation will use the typical value for alpha. Overrides value for alpha, so if you want to use you own alpha, regardless of units, set this to False.
- Returns
RHOB estimate in \(kg/m^3\).
- Return type
ndarray
- bruges.petrophysics.petrophysics.velocity_to_slowness(slowness)#
Convert a slowness log in µs per unit depth, to velocity in unit depth per second.
- Parameters
slowness (ndarray) – A value or sequence of values.
- Returns
The velocity.
- Return type
ndarray