Pre Stack Depth Migration: Case Study of Seismic 3D Offshore Data

• Main Author: RAHADIAN A. (NIM : 12405009), M.
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/23134
• Institution: Institut Teknologi Bandung

On a sub-surface structure with quite variations in lateral velocity and well-distributed fault, it needs a method to facilitate a better subsurface image which in the end it will helps to give a better interpretation in depth domain. Therefore, we are using PSDM method to facilitate it and hopefully, there would be a significant improvement in subsurface image and velocity <br /> <br /> <br /> <br /> <br /> model compare to PSTM method in time domain. <br /> <br /> <br /> <br /> <br /> In this case, I used an offshore 3D seismic data. In previous process, PSTM method was already performed and next step is to use the PSDM method with inputs: 3D PSTM section, CMP Gather, and RMS velocity. The sub-surface image of PSTM is good enough in showing fault image and reflectors. We also can see a flat CMP gather and a really good velocity model in vertical perspective in this step. Then, with these inputs, the 3D Kirchhoff PSDM method was performed on specific in-lines and cross-lines until we got the PSDM section in depth domain. It was also being performed an updating velocity interval in depth domain using horizon based Tomography. <br /> <br /> <br /> <br /> <br /> In general, PSDM method gives better images. Depth migrated gather of PSDM is flatter compared to CMP gather in time domain of PSTM. Laterally, there is a significant change of interval velocity after PSDM method being performed. Thus, we can conclude that PSDM <br /> <br /> <br /> <br /> <br /> method can give a better subsurface image to interpret compare to PSTM method and can show a difference lateral resolution in depth domain