IMAGING SALTDOME MODEL IN THE PRESENCE OF SHALLOW GAS EFFECT USING CONVERTED WAVE

• Main Author: FIRMAN APRILIAWAN - NIM: 12314002 , ALVIAN
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/25413
• Institution: Institut Teknologi Bandung

<p align="justify">In seismic data processing, the main objective is to build seismic image which best representing subsurface model. But, in reality conventional seismic method (P-P wave ) not always produce a good quality seismic image, for example those in case of shallow gas reservoir. The presence of gas makes the image of reflector below it becomes not clear (blur) because most of P-wave energy was scattered and attenuated when travelling through gas. There is another approach in seismic survey which is called converted waves exploration. This method was inspired by the phenomenon of P wave incidence that converted to P and S wave at the reflector plane. The resulting S wave was recorded at the surface by multicomponent geophone. S wave is used because its energy is less absorbed than those in P wave, so that the reflector beneath shallow gas have better image quality in the P-SV section. In this research, data processing is carried out in both P-P wave in vertical component and P-SV in horizontal component of geophone recording. Each data is processed until become migrated section. Then both section is compared to find the strength and weakness of each method in imaging the synthetic model. Result of the data processing show that horizontal component can image reflector beneath shallow gas reservoir better than in vertical component, but strong multiple was identified in the vertical component and the residual P-P wave was observed in the horizontal component. Filtering process was done to suppress multiple and residual P-P wave using radon and F-K filter. F-K filtering shows improvement in image quality. Based on the fact that upgoing S-wave particle displacement was recorded by both vertical and horizontal component, then P-SV wave is extracted from vertical component which usually used for sensing P-P wave, using asymptotic binning. The resulting image shows reflection phenomenon that was not found before, becomes identified after the extraction. <p align="justify"> <br /> <br />