A new expression for fluid factor using AVO intercept and gradient

Numerous AVO fluid indicators have been introduced and proven to be sensitive to hydrocarbon presence. Mathematically, fluid indicators measure the deviation of seismic responses of hydrocarbon-saturated reservoirs from their background in a specific domain. We introduce a new expression for the fluid factor commonly used in AVO analysis and interpretation. The expression is a function of common AVO intercept and gradient and a weighting coefficient that allows one to suppress the contribution of lithology and other factors not related to fluid content. The performance of the weighted fluid factor is compared with other fluid factor expressions using a worldwide collection of velocity measurements. A case study on the Northwest Shelf of Australia shows that the fluid factor successfully detects known pay intervals.