ATTENUATION OF WATER-BOTTOM MULTIPLES: A CASE STUDY FROM SHAL LOW MARINE IN THE NIGER DELTA, NIGERIA

Abstract

Three-dimensional (3D) seismic data in the shallow offshore Niger Delta was acquired and processed. The dataset at water-depth of 250m was masked by interbed multiples and water bottom multiples. The major differences exploited for the multiples removal were velocity discrimination, frequency, wavelength, periodicity, and predictability using predictive deconvolution and Radon techniques. The dominant frequency of the primary events varies between 3 and 120Hz having dominant amplitude ranging between -12dB and -45dB. The dominant frequency of the multiples ranges between 8 and 90Hz, while dominant amplitude ranges between -5dB and -45dB. Multiples were predominantly short-period with water bottom reverberation having high-frequency and high-amplitude. With the short-period and high-frequency content, the characteristics of the multiples were quite close to those of the primaries. Water-depth and geology are major generators of the waterbottom and interbed multiple energies in a marine environment. The multiple parameters established in this work would be required as inputs in the multiples-attenuation processing program for a better image of the subsurface geology.

Keywords

• Seismic
• processing
• multiples
• attenuation
• shallow marine
• Niger Delta
• Nigeria.