AVO Crossplot Analysis in Unconsolidated Sediments Containing Gas Hydrate and Free Gas: Green Canyon 955, Gulf Of Mexico

Zhang, Zijian (Fugro GeoConsulting, Incorporated) | McConnell, Daniel R. (Fugro GeoConsulting, Incorporated) | Han, De-hua (University of Houston)

OnePetro 

Summary

An analysis of amplitude variation with offset (AVO) observations is applied in hydrate-bearing sands, free-gas- charged sands, and hydrate-over-gas sands. The elastic model parameters (Vp, Vs, and density) are obtained from well log measurements and a rock physics model. The study suggests that presence of gas hydrate and free gas affect the AVO of shallow unconsolidated sediments containing gas hydrate and free gas. Low-concentrated gas hydrate and low-concentrated gas hydrate overlying free gas have weak AVO behaviors while highly-concentrated gas hydrate and highly-concentrated gas hydrate overlying free gas have strong AVO behaviors. Both highly-concentrated gas hydrate and highly-concentrated gas hydrate overlying free gas are Class I AVO anomalies but the intercept of AVO is stronger negative for highly-concentrated gas hydrate overlying free gas. They may occur in different locations in the AVO intercept and gradient plane.