Interpretation of seismic data
When you pick semblance peaks from a velocity spectrum (velocity analysis) to determine the moveout velocity function, you implicitly make a judgment as to what is primary and what is multiple. When you pick a coherency semblance spectrum (model with low-relief structure) to determine the interval velocity profile, you make a judgment as to what degree of lateral velocity variations needs to be honored. These are but two examples of interpretive work involved in processing and inversion of seismic data, respectively.
What is known as traditional seismic interpretation, however, involves picking a reflection time surface associated with a layer boundary from a time-migrated volume of data or a reflector from a depth-migrated volume of data to determine the structure map for that layer boundary (Figure I-19). The power of 3-D visualization of image volumes, velocity volumes, and attribute volumes, such as those associated with AVO analysis and acoustic impedance estimation, have dramatically changed the way seismic interpretation is done now. Interpretation no longer is picking travel-times to determine the structural geology of the area of interest, but also involves manipulation of amplitudes contained in the data volumes to derive information about the depositional environment, depositional sequence boundaries, and the internal constitution of the sequence units themselves. Interpretation of 3-D seismic data has further examples, with case studies, in 3-D structural inversion applied to seismic data from offshore Indonesia and 3-D structural inversion applied to seismic data from the Northeast China.
- Introduction to Seismic Data Analysis
- Processing of seismic data
- Inversion of seismic data
- From seismic exploration to seismic monitoring