Quantifying uncertainties in AVO forward modeling

Ayon K. Dey, Chandra Rai, and Carl Sondergeld

ABSTRACT

A common tool used in the exploration of hydrocarbons is Amplitude-Versus-Offset (AVO) analysis. This particular method has been very effective in identifying major natural gas deposits. Sengupta et al., 1997 shows that the AVO response from data is sensitive to uncertainties in various rock properties. Specifically, the work of Sengupta et al., 1997 shows how the uncertainties in compressional-wave velocities (V P ), shear-wave velocities (V S ), and densities (ρ) project themselves as uncertainties in an AVO response. That is to say, these authors quantify how sensitive the AVO response is to uncertainties in the rock properties.

In this report there is a more detailed analysis of the uncertainties in the rock properties and its effect on the AVO response. The rock properties V P , V S , and ρ are used in AVO forward modeling and the results are analysed. The focus of this work is to define confidence regions for various exploration scenarios and to examine how these different regions interact. The approach taken is to create an elliptical area that contains a certain amount of scatter data (parameters b 0 and b 1 , in this case) and to examine to what degree the various areas overlap.

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