Patent ID: 8666668

Claim:
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 (Vp 0 ) 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 Vp 0 , 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 Vp 0 near the well locations, the values of Vp 0 being updated by a correction ΔVp 0 , wherein Vp 0 =Vp 0 +ΔVp 0 ; c. determining an incremental improvement Δδ to δ(initial) using the relative change Δδ=(ΔVp 0 )/Vp 0 ; 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 Vp 0 =Vp 0 (1−Δδ) using the extrapolated three dimensional Δδ at each of the plurality of subsurface locations and obtaining the three dimensional extended incremental update ΔVp 0 =−Δδ Vp 0 ; 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 Vp 0 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.