In seismic wave propagation, the amplitude decay along travel time comprises two components: the spherical divergence and the earth absorption effect in an inhomogeneous medium. In reservoir geophysics, both the P–P and P–SV wave seismic sections are required to be relative-amplitude preserved so that they can be used for comparative interpretation and analysis. Therefore, each of the following two processing steps, divergence correction and inverse Q filtering, applied to both seismic sections should be relative-amplitude preserved. In this paper, the spherical divergence corrections on the P–P and P–SV wave sections are expressed in unified formulae in which the formula for the P–SV wave section differs from that for the P–P wave section by a factor (1 + γ)-1, where γ is the ratio of P- to S-wave velocities, applicable to both the scale and power coefficients simultaneously. Divergence-corrected seismic sections are then used to estimate the earth Q models, which in turn are used to design inverse Q filters. Only when divergence correction and inverse Q filtering, both of which are amplitude-related processing, applied to the P–P and P–SV wave sections are adequately accurate, the amplitude information contained in these seismic sections can be reliably used for lithological analysis in reservoir geophysics.