Inversion of CMP seismic data

Abstract

We propose a practical scheme for the inversion of common-mid-point (CMP) seismic reflection data. In this scheme both primary and multiple reflections are Jsed to identify layer boundaries using the waveequation. The result of the inversion is the acoustic impedance profile of the equivalent horizontallylayered earth, as a function of two-way travel time l’ he scheme relies on the approximation that a CMP gather can be regarded as a shot gather over an equivalent horizontally layered earth. The CMP data are processed to collapse the source to a point and then decomposed into plane wave components. The effect of the free surface is then removed, the source ravelet is removed by spiking deconvolution, and the resulting plane wave reflection response is inverted using a stabilized recursion scheme ( the discrete Schur algorithm). We present results on synthetic and real data. From the synthetic data we show that the layer stripping scheme is stable when (a) the wavelet is not minimum phase, (b) there is significant noise, (c) the low-frequency information is obtained from stacking velocities and (d) the shallow data are missing. Inversion results on real marine data show good agreement with the impedance derived from a well-log.