Multicomponent VP/VS correlation analysis

Abstract

An important step in the simultaneous interpretation or inversion of multicomponent data sets is to quantitatively estimate the ratio of P‐wave velocity to S‐wave velocity [Formula: see text]. In this endeavor, I have developed correlation techniques to determine long‐wavelength components of [Formula: see text] that can lead to more accurate measurements of rock properties and processing parameters. P‐wave reflections are correlated with converted P‐ to S‐wave reflections (or S‐wave reflections) from the same location to determine which events are related to the same subsurface impedance contrasts. Shear waves are transformed (compressed) to P‐wave time via average [Formula: see text] conjugate operators before correlation. Aided by conventional P‐wave velocity information and petrophysical relationships, this technique provides optimal [Formula: see text] estimates in a similar manner that semblance analyses provide stacking velocities. These estimates can be used to transform the entire S‐wave trace to P‐wave time for short‐wavelength amplitude inversion. Also, a target‐oriented correlation analysis quantitatively determines interval [Formula: see text] at a specific horizon or group of horizons. Data from vertical seismic profile (VSP) stacked traces are used to evaluate these techniques. Long‐wavelength average and interval [Formula: see text] estimates obtained from the correlation analyses agree closely with [Formula: see text] results determined from VSP direct‐arrival traveltimes.