Field Data Example

The proposed methods are tested on a 2D marine dataset. There are 515 shots with a shot interval of 37.5 m, and each shot is recorded by a 6 km long cable with 480 receivers and a 12.5 m interval. The nearest offset is 198 m. These 515 CSGs are transformed into common midpoint profiles (CMPs), and 2D spline interpolation is used to fill in the near-offset trace gap after normal moveout. The interpolated data are then transformed into common receiver gathers with a split-spread acquisition geometry using reciprocity (Vigh and Starr, 2008). In the CRG domain, each trace is multiplied by $\sqrt{i/\omega}$ in the frequency domain and then scaled by $\sqrt{t}$ in the time domain to correct for 3D geometrical spreading (Zhou et al., 1995). A tau-p transform is applied to each CRG to generate 31 plane-wave gathers with ray parameters ($p$ ) ranging from -333$\mu$ s/m to 333 $\mu$ s/m with an even sampling in $p$ . The plane-wave gathers are filtered with a Wiener filter to transform the original wavelet to a Ricker wavelet with a 25 Hz peak frequency. The original wavelet is estimated by stacking traces with a strong water bottom reflection, and windowing the water-bottom reflection event. Figure  shows the plane-wave gather with a surface shooting angle of zero ($p=0$ ). The migration velocity is obtained by waveform inversion (Boonyasiriwat et al., 2010).

Figure: A plane-wave gather with zero surface shooting angle (p=0 $\mu$ s/m).