FULL WAVEFORM MODELLING FOR SUBSURFACE CHARACTERIZATION WITH CONVERTED-WAVE SEISMIC REFLECTION: COMPARISON OF P-P AND P-S FOR A THINBED SUBSURFACE

• Main Author: Ratri Wibowo, Adisti
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/44006
• Institution: Institut Teknologi Bandung

The ability of P-S converted-wave to image the complex geology structure is more reliable than the P-P. In the same P-wave frequency bandwidth, S-wave has the shorter wavelength, therefore the vertical resolution of the S-wave is higher than the P-wave. Using multicomponent receiver, the seismic signals are recorded on the vertical and horizontal components. Both of P-P and P-S wave are recorded on these components, however due to their displacement vector the P-P data would be dominated on the vertical component while on the horizontal component is dominated by the P-S data. The aim for this study is to compare the behavior of the P-P and P-S for the subsurface imaging especially for the existence of a thin-bed. To achieve the purpose of this study, a synthetic model of a thin-bed underneath gas layer was generated by the full waveform modelling. The P-P and P-S seismic data processing are performed to obtain the seismic sections. Processing is also carried out by extracting P-S wave from vertical component. Stack section does not indicate any seismic event, that frequency and fresnel zone analysis of both P-P and P-S waves are performed. The result of this study presents the resolution of P-S is way more reliable than the P-P quality. However, extracting P-S wave from vertical component is more difficult as lower dominant frequency and higher gamma function. This depends on configuration and parameters of the seismic acquisition geometry.