Elastic Parameter Estimation from the 2D Waveform Inversion of a Look-Ahead Walk-Away VSP Survey

Pore pressure in sediments beneath salt in the Gulf of Mexico varies widely creating a potentially dangerous and difficult drilling challenge. The elastic parameters are key to identifying many attributes, but in this paper the elastic parameters are being estimated with the aim of predicting the pore pressure in the sedimentary layer immediately below the salt. The elastic parameters have previously been estimated using an AVO type approach. In this paper we investigate the ability of full waveform inversion to estimate the P-wave and S-wave velocity models from a walk-away VSP in the context of a salt dome. Results demonstrate the ability to further localize the position of the bottom of the salt and extract velocity information beneath the salt.