UTIG RESEARCH PROJECTS ARCHIVE

Principal Investigators: Mrinal K. Sen and Paul Stoffa

Funded by: National Science Foundation - Ocean Sciences

The contrasts in the elastic properties of rocks are manifested in seismic waveform data as variations in arrival times and amplitudes of reflection events recorded in the seismograms. One example is the amplitude variation with offset (also called AVO effect) which has been used by exploration seismologists as a diagnostic in the direct detection of hydrocarbons. While AVO has been used primarily as an exploration tool, several academic multichannel seismic datasets also show significant AVO effects. For example, the bottom simulating reflectors (BSR), whose primary effect in the stacked CDP section is a bright spot, also show a continuous increase in amplitude with offset. Here we propose to develop a more rigorous technique of AVO inversion for the application to marine multi-channel seismic data.

Typically, AVO inversion is a two-step procedure. The first step is to compute the background (or low frequency component) velocity model and the second step is to compute the high frequency components of the material property, e.g., compressional wave velocity (a), shear wave velocity (b), fluid factor, porosity, etc. We propose to use global optimization methods such as simulated annealing and genetic algorithms to estimate the background velocity field combined with a very simplistic approach to derive estimates of the high frequency material property components. We propose to couple the two approaches in an efficient manner. We show some preliminary results of our application to synthetic and real data. Our primary objective here is to develop, test and then evaluate the proposed methodology in the estimation of material properties from multi-channel seismic data. Our resulting methods will be evaluated using synthetic seismic data based on well logs and high quality seismic reflection data collected by the University of Texas Institute for Geophysics off the east coast of the United States, where a BSR is observed.