PRIMAL: Remnant Multiple Attenuation

Conventional demultiple processes based on velocity discrimination (e.g., WLS Radon Demultiple) often leave behind remnant multiple energy on prestack gathers. Advanced multiple removal techniques, such as 3D SRME, can also leave behind unmodeled energy that may have been aliased on the input data. This multiple energy can propagate through stack and mask subtle structural or stratigraphic reservoir details.

We have developed post-Radon isolating multiple algorithm (PRIMAL) to attack this problem. PRIMAL applies a spectral decomposition to attenuate residual multiple energy after another demultiple process has been applied.

PRIMAL can be used to attack various forms of remnant multiple:

  • Near-trace multiple energy where velocity discrimination alone was unable to separate primary from multiple.
  • Diffracted multiple energy that does not follow the hyperbolic assumptions of WLS Radon Demultiple.
  • Some forms of aliased multiples.
  • Typical application is in deepwater environments where the multiple and primary energy exhibit differences in bandwidth.

PRIMAL is best suited for transient multiple contamination. Where remnant multiples are strong and spatially consistent, more sophisticated forms of demultiple such as 3D SMP or SWIPE: Shifted Apex PRT Demultiple should be considered.

While PRIMAL was originally designed to address residual multiple contamination post-Radon, the technique is flexible and can be employed for general purpose residual multiple attenuation where the noise energy can be separated from primary by spectral decomposition. PRIMAL has been successfully used to attenuate residual multiple on both pre- and post-imaged data.

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