Abstract

There are many seismic cubes in Mexico and it remains unclear up to which point their azimuthal anisotropy can be evaluated. This is important as the majority of the reserves in Mexico so far are in fractured reservoirs. Clarity can be provided by a geometrical feasibility study, followed by convolutional modeling and azimuthal amplitude vs. offset (or angle) analysis (often abbreviated as AVAz or referred to as Azimuthal AVO). The critical seismic noise level and formation thickness for this to work are determined. A final conclusion can then be drawn on the viability of an azimuthal study on the seismic cube at hand.

Initially three seismic land datasets are evaluated from souther Mexico, one of which is selected for further azimuthal analysis. The convolutional and noise modeling are done at a well location. Fracture parameters are based on the image logs and core data from the well, together with relationships from literature.

The geometrical feasibility evaluates the overall seismic fold by offset and azimuth. Knowing the depth of the target, the limiting incidence angles are estimated. Hence first conclusions can be drawn on the seismic cubes’ candidacy for azimuthal studies.

The convolutional part is realized at locations with well information, generating several models with different parameters—mainly seismic noise level and target formation thickness. The models are then analyzed with the seismic azimuthal AVO. The critical seismic noise level is estimated beyond which the simulated anisotropy is not recoverable anymore and in a similar fashion the critical target formation thickness. The earlier conclusions can then be finalized; feasible candidates for seismic azimuthal anisotropy analysis to characterize fractures are then identified.