Abstract
AVO inversion is hard to be efficiently applied in unexploited fields due to the insufficiency of well information. For the sake of AVO inversion in a well-absent area, the most conventional method is to construct pseudo well-logs by defining seismic processing velocity as the P-velocity and computing S-velocity and density using empirical formulas, yet the resolution of the corresponding earth models and final inverted results could be extremely low, and a rough formula could destroy the inversion thoroughly. To overcome this problem, an amplitudenormalized pseudo well-log construction method that reconstructs pseudo well-logs in accordance with computed P-wave reflection amplitudes and nearby drilling data is proposed in this paper. It enhances the inversion resolution efficiently with respect to the real elastic parameter relationships, so that the corresponding AVO inversion results are reasonably improved. In summary, the proposed method is successfully applied in the AVO inversion of a well-absent marine area, and could be valuable in the early phase, particularly of the offshore hydrocarbon exploration.
Highlights
The pre-stack seismic AVO inversion is better for reservoir prediction than post-stack methods owing to its preservation of the AVO information and more elastic parameters (Connolly 1999, Zhang et al 2011b), but it cannot be efficiently conducted if the well information is insufficient to accurately scale the wavelets and build constrained elastic models
By this method the resolutions of corresponding earth models and final results directly inverted from seismic processing velocities could be extremely low, and using a rough formula for elastic parameters prediction could further destroy the inversion (Zhang et al 2011b, Fan et al 2013)
In order to increase the resolution of well-absent AVO inversion results and retrieve reliable elastic parameters for reservoir description, we propose a new pseudo well-log construction method and apply it in an undrilled marine study area, where quite promising but not wellstudied reef and turbidity sand reservoirs need to be appraised for further exploration
Summary
The pre-stack seismic AVO inversion is better for reservoir prediction than post-stack methods owing to its preservation of the AVO information and more elastic parameters (Connolly 1999, Zhang et al 2011b), but it cannot be efficiently conducted if the well information is insufficient to accurately scale the wavelets and build constrained elastic models. For a convenient application of AVO inversion method in a well-absent area, the most conventional way is to construct some pseudo well-logs by defining interval velocities obtained from 3D seismic processing stage, initially as the P-velocities, and compute S-velocities and densities using empirical formulas. By this method the resolutions of corresponding earth models and final results directly inverted from seismic processing velocities could be extremely low, and using a rough formula for elastic parameters prediction could further destroy the inversion (Zhang et al 2011b, Fan et al 2013).
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