PEMBUATAN MODEL KECEPATAN DENGAN TOMOGRAFI UNTUK PRE-STACK MIGRASI KEDALAMAN PADA PENCITRAAN STRUKTUR BAWAH PERMUKAAN YANG KOMPLEKS.

• Main Author: Azalia, Annise
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/72671
• Institution: Institut Teknologi Bandung

In complex geologic structure (faults and subsalt), time migration algorithms generate error resulting from lateral velocity variation causes energy diffraction. The proper focusing of diffracted energy requires application of a Pre Stack Depth Migration (PSDM). PSDM is commonly accepted as the best method available fo accurate imaging since its sensitivity to errors in the interval velocity-depth model. For a Pre-Stack Depth Migration project to be successful, a reliable interval velocity-depth model is essential. Multiple iteration of Pre Stack Depth Migration are often required to achieve a sufficiently reliable model. This final project focuses on velocity model building in PSDM using minimum traveltime reflection tomography concept iteratively in field seismic data. PSDM requires an acurate interval velocity model to achieve optimum results. It is possible to build a regional interval velocity model in a time and cost effective manner which can be utilised in the PSDM process to generate a more optimal subsurface image. The process requires utilization of RMS velocities from the seismic data. This regional RMS velocities field is subsequently converted into a regional interval velocity field. Any available geological information is incorporated at this stage to constraints to the model. The interval velocity model is then sub-divided into discrete velocity layers which match as closely as possible the geological horizon. The velocity model is refined and updated though a number of PSDM iterations using tomographic updates. A proper velocity depth model requires convergency , consistency, and flatness criteria. In this condition results enhancement image resolution.