rockphypy.AVO

Module Contents

Classes

AVO	Exact and approximations of reflectivity in isotropic and anisotropic media.

class rockphypy.AVO.AVO

Exact and approximations of reflectivity in isotropic and anisotropic media.

static AVO_HTI(D1, D2, C1, C2, theta, azimuth)

Compute azimuth dependent PP reflectivity for wealy anisotropic HTI media using Ruger’s approximation

Parameters:

• D1 (float or array-like) – density of the upper medium g/cm3

• D2 (float or array-like) – density of the lower medium g/cm3

• C1 (2D array) – stiffness matrix of the upper medium

• C2 (2D array) – stiffness matrix of the lower medium

• theta (array-like) – incident angle, in degree unit

• azimuth (array-like) – azimuth angle, in degree unit

Returns:

float or array-like – PP reflectivities

static Aki_Richards(theta, vp1, vp2, vs1, vs2, den1, den2)

Aki-Richard approximation to PP reflectivity.

Parameters:

• theta (float or array-like) – incident angle, degree

• vp1 (float) – P wave velocity of layer 1, m/s

• vp2 (float) – P wave velocity of layer 2, m/s

• vs1 (float) – S wave velocity of layer 1, m/s

• vs2 (float) – S wave velocity of layer 2, m/s

• den1 (float) – density of layer 1, kg/m3

• den2 (float) – density of layer 2, kg/m3

Returns:

float or array-like – R_pp: P wave reflectivity R_ps: PS reflectivity Rpp0: intercept gradient

static zoeppritz(vp1, vs1, rho1, vp2, vs2, rho2, theta)

Reflection & Transmission coefficients calculated using full Zoeppritz equations.

Parameters:

• vp1 (float) – P wave velocity of layer 1, m/s

• vs1 (float) – S wave velocity of layer 1, m/s

• rho1 (float) – density of layer 1, kg/m3

• vp2 (float) – P wave velocity of layer 2, m/s

• vs2 (float) – S wave velocity of layer 2, m/s

• rho2 (float) – density of layer 2, kg/m3

• theta (float or array-like) – incident angle, degree

Returns:

float or array-like – Rpp,Rps: PP and PS reflectivity

static AVO_abe(vp1, vs1, d1, vp2, vs2, d2)

Different approximations AVO terms

Parameters:

• vp1 (float or array-like) – P wave velocity of layer 1, m/s

• vs1 (float or array-like) – S wave velocity of layer 1, m/s

• d1 (float or array-like) – density of layer 1, kg/m3

• vp2 (float or array-like) – P wave velocity of layer 2, m/s

• vs2 (float or array-like) – S wave velocity of layer 2, m/s

• d2 (float or array-like) – density of layer 2, kg/m3

Returns:

float or array-like – different linear AVO approximations

static EI_ref(Vp, Vs, rho, theta, SP, norm=True)

Compute elastic impedance of an isotropic, flat-layered Earth

Parameters:

• vp1 (float or array-like) – P wave velocity of layer 1, m/s

• vs1 (float or array-like) – S wave velocity of layer 1, m/s

• d1 (float or array-like) – density of layer 1, kg/m3

• Vp (float or array-like) – P wave velocity

• Vs (float or array-like) – S wave velocity

• rho (float or array-like) – density

• theta (array-like) – incident angles

• SP (float) – constant ratio of Vs to Vp, can be taken as the average of input Vs/Vp, i.e. SP= VS.mean()/VP.mean()

• norm (bool, optional) – If True: normalized input velocities and density such that the units and dimension match with acoustic impedance. Defaults to True.

Returns:

float or array-like – EI_pp: elastic impedance for PP reflection EI_svp: elastic impedance for P-SV reflection EI_psv: elastic impedance for SV-P reflection EI_svsv: elastic impedance for SV-SV reflection EI_shsh: elastic impedance for SH-SH reflection

static AVO_ortho(a1, b1, e11, d11, e12, d12, g1, rho1, a2, b2, e21, d21, e22, d22, g2, rho2, the)

calculates the reflectivity in the symmetry plane for interfaces between 2 orthorhombic media, refactered from srb toolbox written by Diana Sava. :param a1: P-wave vertical velocities of upper medium (1) :type a1: float or array-like :param b1: S-wave vertical velocities of upper medium (1) :type b1: float or array-like :param e11: epsilon in the two symmetry planes of the orthorhombic medium for the upper medium (first index indicates the upper medium (1), second index indicates the plane of symmetry (1 - plane perpendicular to x, 2 - plane perpendicular to y); :type e11: float or array-like :param d11: delta in the two symmetry planes of the orthorhombic medium for the upper medium :type d11: float or array-like :param e12: epsilon in the two symmetry planes of the orthorhombic medium for the upper medium :type e12: float or array-like :param d12: delta in the two symmetry planes of the orthorhombic medium for the upper medium :type d12: float or array-like :param g1: vertical shear wave splitting parameter for the upper medium (1) :type g1: float or array-like :param rho1: density of the upper medium :type rho1: float or array-like :param a2: P-wave vertical velocities of lower medium (2) :type a2: float or array-like :param b2: S-wave vertical velocities of lower medium (2) :type b2: float or array-like :param e21: epsilon in the two symmetry planes of the orthorhombic medium for the lower medium :type e21: float or array-like :param d21: delta in the two symmetry planes of the orthorhombic medium for the lower medium :type d21: float or array-like :param e22: epsilon in the two symmetry planes of the orthorhombic medium for the lower medium :type e22: float or array-like :param d22: delta in the two symmetry planes of the orthorhombic medium for the lower medium :type d22: float or array-like :param g2: vertical shear wave splitting parameter for the upper medium (2) :type g2: float or array-like :param rho2: density of the lower medium :type rho2: float or array-like :param the: incident angle :type the: float or array-like

Returns:

array-like – Rxy: PP reflectivity as a function of angle of incidence in xz plane (13). Ryz: PP reflectivity as a function of angle of incidence in yz plane (23)