ESTIMATION OF EFFECTIVE SOURCE SIGNATURES FROM MARINE VSP DATA

We present a simple method for estimating an effective source wavelet from the first arrival in marine vertical seismic profiling (VSP) data . The method, which utilizes the free-space Green's function of the He lmholz equation, is simple and very computer efficient. We show exampl es from synthetic and real offset and walk-away VSP data. In the synth etic examples, we show that data modelled with the estimated wavelet g ive small residuals when subtracted from the reference data. In the re al data examples, we show that when modelling with the wavelet estimat ed from the real data, in a smooth macromodel, we obtain a good fit be tween the first arrivals in the real and modelled data.