Maximum effectiveness of the CRP method can be obtained only when the reflections to be stacked are in perfect time alignment on all traces. Unavoidable misalignments due to inexact datum and normal moveout corrections usually can be determined by visual or machine correlation within the common-point collection groups. The question then becomes, "Are the observed variations sufficiently large to justify reprocessing with refined corrections and how much improvement could be so obtained?"

The reductions in effectiveness for various degrees of common coverage are derived for two hypothetical signals; a continuous sine wave, and a symmetrical Ricker wavelet. Two separate cases are considered for each signal. In the first case the signals of a suite are linearly distributed through a maximum time difference. In the second case a hyperbolic distribution, such as would be found because of an error in total moveout, is used. The results of all four cases are presented in normalized form, and can be applied universally to records of any frequency.

The range of error values which is investigated is sufficiently large to indicate the degree to which multiple reflections can be attenuated with large amounts of excess moveout.

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