P/S separation of OBS data by inversion in a homogeneous medium

Existing P/S separation methods

Amundsen (1993); Wapenaar et al. (1990); Dankbaar (1985) have shown how to separate the P and S-waves of OBS data, and also separate between the upgoing and downgoing pressure energy. Their methods require a knowledge of medium parameters in the vicinity of the receivers. Schalkwijk et al. (2003) implement adaptive decomposition, in order to account for the unknown near-surface medium parameters on which the separation depends. This decomposition requires manual identification in each receiver gather of a single time window containing mainly downgoing waves, and of a window that contains mainly upgoing waves. The energy within these windows is then minimized using an itterative process. The filter resulting from this process is inverted for both the local medium parameters and the calibration between the different sensors.

Zhou et al. (2011) propose a novel method of extracting the P-wave data from the geophone components. It involves a complex wavelet transform of the hydrophone and the vertical geophone data. A matching of the geophone data to the predominantly P-wave energy hydrophone data is done in the complex wavelet domain. Afterward, the inverse transform is applied to the result. The end product is a substantially P-only vertical geophone component. PZ summation can then be applied to this component and the recorded hydrophone, to separate the upgoing from the downgoing P-wave.

P/S separation of OBS data by inversion in a homogeneous medium