rockphypy.Perm

Recreation and modifcations of the Permeabilities models in Rock physics handbook matlab tools.

Module Contents

Classes

Permeability

Different permeability models.

class rockphypy.Perm.Permeability

Different permeability models.

static Kozeny_Carman(phi, d)

Describe the permeability in a porous medium using Kozeny-Carman equation assuming the turtuosity tau=sqrt(2), 1/B=2.5 for unconsolidated monomodal sphere pack.

Parameters:

• phi (float or array-like) – porosity

• d (float) – pore diameter in m.

Examples

>>> phi= np.linspace(0.01,0.35,100)
>>> d= 250
>>> k= Kozeny_Carman(phi, d)
>>> plt.semilogy(phi, k )

Returns:

float or array-like – k (m^2): the resulting permeability is in the same units as d^2

static Kozeny_Carman_Percolation(phi, phic, d, B)

The Kozeny−Carman relations incorporating the percolation effect

Parameters:

• phi (float or array-like) – porosity

• phic (float) – percolation porosity

• d (float) – pore diameter

• B (float) – geometric factor that partly accounts for the irregularities of pore shapes.

Returns:

float or array-like – k (m^2): the resulting permeability is in the same units as d^2

static Owolabi(phi, Swi)

Estimate the permeability in uncosonlidated sands of Pleistocene to Oligocene age in Eastern Niger Delta from log derived porosityand irreducible water saturation.

Parameters:

• phi (float or array-like) – porosity

• Swi (float or array-like) – irreducible water-saturation from welllogs

Returns:

float or array-like – k_oil, k_gas: permeabilities in mD for oil and gas sand reservoir, respectively

static Perm_logs(phi, Swi)

Various empirical correlations of between permeability, porosity and irreducible water-saturation from welllogs. Models includs Tixier, Timur, Coates and Coates-Dumanoir.

Parameters:

• phi (float or array-like) – porosity

• Swi (float or array-like) – irreducible water-saturation from welllogs

Returns:

• float or array-like – k_tixier, k_Timur , k_coates, k_coates_Dumanoir: different permeability estimations, in the unit of mD

• Assumptions

• ———–

• - The functional forms used in these equations have to be calibrated, whenever possible, to site-specific data.

• - The rock is isotropic.

• - Fluid-bearing rock is completely saturated.

static Panda_Lake(d, C, S, tau, phi)

Modified Kozeny-carman relation incorpating the contribution of grain size variation and sorting using Manmath N. Panda and Larry W. Lake relation.

Parameters:

• d (float) – mean particles size in um.

• C (float) – coefficient of variation of particles size distribution

• S (float) – skewness of particles size distribution

• tau (float) – tortuosity factor

• phi (float or array-like) – porosity

Returns:

float or array-like – k (md): permeability

References

• Estimation of Single-Phase permeability from parameters of particle-Size Distribution, Manmath N. Panda and Larry W. Lake, AAPG 1994.

static Panda_Lake_cem(phi, d)

Quantify the effects of cements on the single phase permeability estimate of unconsolidated sand using Panda & Lake model

Parameters:

• phi (float or array-like) – porosity

• d (float) – mean particles size in um

Returns:

float or array-like – k (md): permeability

static Revil(phi, d)

Estimate permeability in very shaly rock using Revil et al. 1997

Parameters:

• phi (float or array-like) – porosity

• d (float) – mean particles size in um

Returns:

float or array-like – k (md): permeability

static Fredrich(phi, d, b)

Compute permability considering Pore Geometry and Transport Properties of Fontainebleau Sandstone

Parameters:

• phi (float or array-like) – porosity>10%

• d (float) – _description_

• b (float) – shape factor b is equal to 2 for circular tubes and equal to 3 for cracks.

Returns:

• float or array-like – k (md): permeability

• References – ———-

• - Fredrich, J. T., Greaves, K. H., & Martin, J. W. (1993, December). Pore geometry and transport properties of Fontainebleau sandstone. In International journal of rock mechanics and mining sciences & geomechanics abstracts (Vol. 30, No. 7, pp. 691-697). Pergamon.

static Bloch(S, C, D)

Predict porosity and permeability in sandstones prior to drilling using Bloch empirical relations obtain in Yacheng field.

Parameters:

• S (float) – Trask sorting coefficient

• C (float) – Rigid grain content in frac

• D (float) – Grain size in mm

Returns:

float or array-like – phi, k: porosity (frac) and permeability (mD), respectively

static Bernabe(phi, crf, w, r)

Bernabe models permit to compute the permeability and porosity of strongly pressure dependent pores such as cracks and approximately constant pores associated with tubes and nodal pores.

Parameters:

• phi (float or array-like) – total porosity

• crf (float) – crack fraction in pore volume

• w (float) – width or aperture of the equivalent crack in um

• r (float) – radius of the tube in um

Returns:

• float or array-like – k (md): total permeability

• References – ———-

• - Bernabe, Y. (1991). Pore geometry and pressure dependence of the transport properties in sandstones. Geophysics, 56(4), 436-446.