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Velocity model is the input data for Pre Stack Depth Migration (PSDM). The success of PSDM process is highly depends on the quality of velocity model. Determination of velocity model using reflection tomographic inversion is presented in this study. This process uses kinematic wavefield attributes o...
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| Format: | Final Project |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/13167 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Velocity model is the input data for Pre Stack Depth Migration (PSDM). The success of PSDM process is highly depends on the quality of velocity model. Determination of velocity model using reflection tomographic inversion is presented in this study. This process uses kinematic wavefield attributes obtained from CRS stack method. The reliability of this method is applied in synthetic case study. By applying this method, the quality of subsurface image obtained from PSDM will be increased.<p> The inversion process is started with preparing wavefield attributes obtained from ZO CRS-stack method. The main input for this inversion is RNIP attribute, emerge angle attribute, and picking of ZO samples. From those, one can determine normal ray traveltime, second spatial traveltime derivatives, first spatial traveltime derivatives, and spatial coordinate. Starting model must then be constructed by defining the near surface velocity and velocity gradient as a function of depth. Tomographic inversion tries to minimize the difference between observed data and calculated forward modeling data. The final velocity model is accepted if the misfit is already reached its minimum value. Since the stack section resulted from CRS stack shows better description about subsurface, then there will be no doubt to pick the reflector information, although the seismic data has low fold coverage.<p>This method has an output in form of macro velocity model information defined in depth unit. Furthermore, the macro velocity model can give useful information in pre stack depth migration process. There are three other output as additional result, they are velocity values in each grid, forward modeled data, and misfit data, which can be use as addition to control the quality of velocity model. |
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