Pre‐stack seismic inversion of offset stacked data: Diagnostics and remedies for overestimated angles of incidence, a case study

Abstract

Summary In seismic inversion, multiple sub-stacked seismic data volumes are used to derive the petro-elastic parameters such as acoustic impedance and Poisson’s Ratio. The relation between the seismic data and these parameters depends on the angle dependent reflectivity. Here, we present a series of diagnostics from which we determine that the angles of incidence used in our case study are overestimated. Without correction this overestimation would lead to sub-optimal inversion results. A systematic approach is used in which the diagnostics are monitored to arrive at optimised angles of incidence. In the case study, we found that a reduction in the angles of incidence of approximately 3 (Near), 5 (Mid) and 9 (Far) improved the wavelets extracted at two well locations and improved the quality of the well synthetics to seismic ties. And for these reduced angles, the accuracy and detail in the petro-elastic properties derived from simultaneous pre-stack seismic inversion improved significantly. We conclude that in the context of simultaneous pre-stack seismic inversion an accurate determination of angles of incidence becomes vital when seismic sub-stack angles of incidence approach critical angle.