Use of Rock Physics Principles for Inversion of Pre-Stack Seismic Data

Full waveform pre-stack inversion of seismic data usually provide a more accurate and reliable estimate of the elastic properties of the earth over conventional AVO analysis, as it can account for the contamination of seismic amplitudes from other wave modes. However as in all other types of inversion pre-stack full waveform inversion is also sensitive to the starting model and other apriori information. Conventionally well logs available in the area are used for this purpose. However, dipole sonic log in most cases is not available due to cost and P-wave sonic and bulk density logs are not available in the shallow parts due to large holes. In this abstract, we present a general rock physics based technique for constructing pseudo logs and then use them to build our initial models for pre-stack waveform inversion of seismic data. The pseudo-shear sonic log calculation is based on the work by Dutta and Wendt (1993). Another set of pseudo-logs are based on mechanical compaction theory and rock physics based velocity porosity relationships. We test inversion results for both the techniques on well log synthetic from deep water Gulf of Mexico.