US 2010/0135115 A1 · MULTIPLE ANISOTROPIC PARAMETER INVERSION FOR A TTI EARTH MODEL

Abstract

A method for determining values of anisotropic model parameters of a Tilted Transversely Isotropic (TTI) Earth model, the anisotropic parameters including P-wave velocity (Vp0) along a tilted symmetry axis, the Thomsen anisotropy parameters δ and ε (or η=(ε−δ)/(1+2δ)) representative of variations of wave velocities as a function of wave propagation angle from the symmetry axis, the method including acquiring input data for a geological volume of interest; determining a theoretical relationship between the input data and the anisotropic model parameters; and calculating the values of the anisotropic model parameters at each of a plurality of subsurface locations in the geological volume of interest based on the theoretical relationships and the input data using workflows involving iterative or sequential combinations of processes including input data preprocessing, conventional tomographic inversion, three dimensional tomographic inversion based on a tilted transversely isotropic model, and three dimensional pre-stack depth migration using a tilted transversely isotropic model.

Claims16

Dependent claims

A computer implemented method for determining values of anisotropic model parameters of a Tilted Transversely Isotropic (TTI) Earth model, the anisotropic parameters including P-wave velocity (Vp0) along a tilted symmetry axis, the Thomsen anisotropy parameters δ and δ (or η=(ε−δ)/(1+2δ)) representative of variations of wave velocities as a function of wave propagation angle from the symmetry axis, the method comprising:

acquiring input data for a geological volume of interest;
determining a theoretical relationship between the input data and the anisotropic model parameters;
and
calculating the values of the anisotropic model parameters at each of a plurality of subsurface locations in the geological volume of interest based on the theoretical relationships and the input data using workflows involving iterative or sequential combinations of processes including input data preprocessing, conventional tomographic inversion, three dimensional tomographic inversion based on a tilted transversely isotropic model, and three dimensional pre-stack depth migration using a tilted transversely isotropic model, thereby providing an accurate model of geological features present in the geological volume of interest.

1 more element

A computer implemented method for determining values of anisotropic model parameters of a three dimensional TTI earth model, the anisotropic parameters including P-wave velocity (Vp0) along a tilted symmetry axis, the Thomsen anisotropy parameters δ, ε (or η=(ε−δ)/(1+2δ)) representative of variation of wave velocities as a function of wave propagation angle from the symmetry axis, the method comprising:

a. obtaining an initial TTI earth model that substantially flattens common-imaging-point gathers and substantially ties seismic data to well data, the initial migration velocity model including initial values Vp0, δ, ε (or η) at each of a plurality of subsurface locations in a geological volume of interest;
b. inputting checkshot data, or VSP data, or both checkshot and VSP data at well locations into a three dimensional tomographic inversion to determine updated values of Vp0 near the well locations, the values of Vp0 being updated by a correction ΔVp0, wherein Vp0=Vp0+ΔVp0;
c. determining an incremental improvement Δδ to δ(initial) using the relative change Δδ=(ΔVp0)/Vp0;
d. extrapolating the relative change Δδ from near-well locations to the entire three dimensional TTI earth model at each of the plurality of subsurface locations, taking into account geological consistency and regularization, to determine updated values of δ, wherein δ=δ+Δδ;
e. determining updated values of Vp0=Vp0(1−Δδ) using the extrapolated three dimensional Δδ at each of the plurality of subsurface locations and obtaining the three dimensional extended incremental update ΔVp0=−Δδ Vp0;
f. inputting near-to-mid-offset/angle residual moveout information in the common-imaging-point gathers obtained with an improved migration velocity model that is defined with the updated values of Vp0 and δ into a TTI tomographic inversion process to further provide updated values of δ at each of the plurality of subsurface locations;
and
g. inputting near-to-far-offset/angle residual moveout information in the common-imaging-point gathers obtained with the improved model the TTI tomographic inversion process to provide updated values of η at each of the plurality of subsurface locations.

5 more elements

Dependencies are inferred from the claim text.

Multiple anisotropic parameter inversion for a tti earth model

Life of this patent

Multiple anisotropic parameter inversion for a tti earth model

Life of this patent

Abstract

Claims16