Vp/Vs ratios through multicomponent velocity analysis

A key step in the multicomponent data processing is the computation of the Vp/Vs ratios. In this paper we show that a multicomponent velocity analysis can combine information from horizontal and vertical components into a single panel and can therefore improve the accuracy of the velocity estimate. In addition a multicomponent velocity analysis followed by Common Conversion Points binning can indicate the Vp/Vs ratios that produce the optimum focusing of the coherence panel in the case of dipping reflectors. The multicomponent panel, in which the velocity analysis is performed, is obtained by adding in quadrature the horizontal and the vertical responses. One of the main advantages is that the velocity analysis carried out on a single gather facilitates the velocity picking that, otherwise, would have to be repeated for each orthogonal component. Moreover, lithologic bounds on the Vp/Vs ratio can be more easily checked because the trends of pure and converted waves are mapped together. Tests performed on synthetic and real data show that the multicomponent velocity analysis provides accurate velocity estimations even for data at the early steps of processing.