Importance

Loading Importance Indicators...

Abstract

A method and system for producing an indicator for amplitude-versus-offset (AVO) analysis of seismic survey data is disclosed. According to the disclosed method and system, a raw AVO indicator is generated for each of multiple depth points, from the AVO intercept and gradient coefficient values. The indicator is generally a positive amplitude number for those locations having petrophysical importance, while the background neighboring points will have a zero or negative value for the raw indicator. Statistics are derived for a group of depth points that surround the depth point under analysis, in time and in space, from which a probability function may be evaluated, assuming a distribution of values in the background trend of AVO intercept and gradient values, and based upon which the raw AVO indicator will be modified. In one embodiment, the probability function is evaluated to determine the loci of points that are within the background to a certain statistical confidence. The modified AVO indicator is set to zero for points within the loci, so that a depth point having a positive raw AVO indicator but within the statistical spread of points in the survey will not be falsely identified as petrophysically important. According to a second embodiment, the probability function for the depth point under analysis is evaluated, and the result combined with the raw AVO indicator to produce the modified indicator; points within the statistical spread of the background have greatly devalued modified AVO indicators according to this embodiment.

Loading the Abstract Image...

First Claim