Study On Avo Fluids Detection In Gas Exploration In Huanghekou Sag Of Bohai Bay

There are a lot of typical seismic bright spot that is response of shallow gas in Huang he kou sag of Bohai bay, moreover, high amplitude, frequency loss and low frequency shadow also are response of shallow gas. Bright spot technology only use seismic data of zero degree incidence, but AVO technology use all of incidence seismic data, so AVO technology is more credible than Bright spot technology at fluid interpretation. There are two part in this study, one is rockphysics analysis, another is forward modeling of AVO study. 37 well log dada of Huang he kou sag were statistics to get Rockphysics rule of Minghuazhen formation. The Rockphysics model and cross-plot between seismic data and log data were make up, we get many elastic parameters in different fluid state base on fluid substitution technology. It is be testified that the 3rd kind sand was displayed after 1st ,2nd and 3rd sand were injected oil or gas by Zoeppritz equation. We also get theoretical AVO curve of different kind sand and hydrocarbon indicate of AVO. It is can directly identify different fluid. Use Shuey's equation, we can get intercept and gradient of AVO analysis from CRP gather, they can also directly identify oil, gas from brine. It is be testified that AVO forward modeling can effectually identify thick hydrocarbon sand, but it is risk to identify thin hydrocarbon sand because of tune effect.