Depth Domain Inversion Case Study in Complex Subsalt Area

Abstract

Geophysical reservoir characterisation in a complex geologic environment remains a challenge. Conventional amplitude inversion assumes true seismic amplitudes. In a complex subsalt environment, inadequate illumination of the subsurface due to complex geology or the acquisition geometry has detrimental effects on the amplitudes and phase of the migrated image. Such effects are not compensated for in conventional seismic inversion techniques. Consequently an imprint of various non-geological effects, including illumination, will manifest themselves in the results of seismic inversion, leading to a less reliable estimation of the resultant elastic and rock properties. The depth domain inversion workflow uses point spread functions to capture the dip dependent effects due to acquisition geometry and complex geology. The amplitude inversion is performed in the depth domain and the output is a reflectivity image corrected for illumination effects. This provides better event continuity, a sharper image, more reliable amplitude information resulting in an improved structural and quantitative interpretation. This paper presents the results of a field data example where depth domain inversion is applied in a complex subsalt environment.