Method and system that uses an anisotropy parameter to generate high-resolution time-migrated image gathers for reservoir characterization, and interpretation

A computing system for performing a method that uses time-migrated common image gathers, to generate an anisotropy parameter to obtain high-resolution time-migrated image gathers for reservoir characterization, and interpretation. The system comprising:

• a telemetry system for sending and receiving pre-stack seismic data from a survey region;
• a memory resource, for storing data;
• a computer system output device;
• and
• a non-transitory computer readable memory device coupled to the telemetry system, coupled to the memory resource, and coupled to the computer system output device, programmed for performing the operations of:
• acquiring pre-stack seismic data, wherein the pre-stack seismic data includes common shot gathers with horizonal axis of offset and vertical axis of time;
• pre-processing an initial anellipticity anisotropy parameter using conventional anellipticity anisotropy parameter analysis with long-spread P-wave data;
• pre-processing a baseline normal-moveout velocity using conventional hyperbolic moveout analysis from a near-offset P-wave data or from a pre-migrated nonhyperbolic moveout analysis using long-spread P-wave data;
• storing the acquired pre-stack seismic data, the acquired initial anellipticity anisotropy parameter, and the acquired baseline normal-moveout velocity to a memory resource;
• computing an anisotropic Kirchhoff time migration partial image, using the stored pre-stack seismic data, the stored initial anellipticity anisotropy parameter, and the stored baseline normal-moveout;
• generating far-offset image gathers with horizonal axis of offset and vertical axis of time, from the computed anisotropic Kirchhoff time migration partial images;
• storing the generated far-offset image gathers, with horizontal axis of offset and vertical axis of time, to the memory resource;
• calculating a plurality of semblance parameters, using the stored far-offset image gathers;
• generating a final semblance volume from the calculated plurality of semblance parameters;
• storing the final semblance volume to a memory resource;
• selecting an updated anellipticity anisotropy parameter from the maxima of the stored final semblance volume;
• storing the updated anellipticity anisotropy parameter to a memory resource;
• computing a perturbation change value, between the updated anellipticity anisotropy parameter and the initial anellipticity anisotropy parameter;
• inputting a user-defined tolerance value;
• setting the stored updated anellipticity anisotropy parameter equal to the initial anellipticity anisotropy parameter;
• repeating the steps of computing an anisotropic Kirchhoff time migration partial images, generating far-offset image gathers with horizonal axis of offset and vertical axis of time, storing the generated far-offset image gathers, with horizontal axis of offset and vertical axis of time, to the memory resource;
• calculating a plurality of semblance parameters, generating a final semblance volume, storing the final semblance volume, selecting an updated anellipticity anisotropy parameter, storing the updated anellipticity anisotropy parameter, computing a perturbation change value, until the computed perturbation change value is less than or equal to the inputted user-defined tolerance value, or until the generated far-offset image gathers are flat;
• and
• generating a final anellipticity anisotropy parameter.