CORRECTING FOR COLOURED PRIMARY REFLECTIVITY IN DECONVOLUTION¹

Statistical deconvolution, as it is usually applied on a routine basis, designs an operator from the trace autocorrelation to compress the wavelet which is convolved with the reflectivity sequence. Under the assumption of a white reflectivity sequence (and a minimum‐delay wavelet) this simple approach is valid. However, if the reflectivity is distinctly non‐white, then the deconvolution will confuse the contributions to the trace spectral shape of the wavelet and reflectivity.

Given logs from a nearby well, a simple two‐parameter model may be used to describe the power spectral shape of the reflection coefficients derived from the broadband synthetic. This modelling is attractive in that structure in the smoothed spectrum which is consistent with random effects is not built into the model. The two parameters are used to compute simple inverse‐ and forward‐correcting filters, which can be applied before and after the design and implementation of the standard predictive deconvolution operators. For whitening deconvolution, application of the inverse filter prior to deconvolution is unnecessary, provided the minimum‐delay version of the forward filter is used.

Application of the technique to seismic data shows the correction procedure to be fast and cheap and case histories display subtle, but important, differences between the conventionally deconvolved sections and those produced by incorporating the correction procedure into the processing sequence. It is concluded that, even with a moderate amount of non‐whiteness, the corrected section can show appreciably better resolution than the conventionally processed section.