Spectral decomposition based gas reservoir identification technique and its application
Huang Rao1,4, Chen Xiao-hong Li Jing-ye1,3
1. CNPC Key Lab of Geophysical Prospecting,China University of Petroleum,Beijing City 102249,China;
2. Education Ministry Key Lab of Oil & Gas Reservoir Forming Mechanism,China University of Petroleum,Beijing City 102249,China;
3. State Key Lab of Petroleum Resources and Prospecting,China University of Petroleum,Beijing City 102249,China
Abstract：When seismic wave propagates through oil gas bearing sandstone,high frequency energy is dramatically attenuated,studying the attenuation could provide useful information for hydrocarbon detection.In this paper for two medium models which are isotropic medium model and the model with caprock being elastic medium and reservoir being attenuated medium respectively,by utilizing three types of gas-bearing sandstone model and based on wave theory reflectivity method,the pre-stack seismic records are modeled respectively,generalized S-transform was used to conduct frequency division processing for modeling records,and the AVO characteristics for different frequencies were analyzed.The studies show that for elastic media AVO response curse is not affected by frequency,but when caprock is elastic medium and reservoir is attenuated medium,AVO response curves for different frequencies are different,and the seismic wave attenuation increases with frequency increase.According to the conclusion the field data in S oilfield were analyzed,the study results show that based on the abnormally high attenuation characteristics of the gas-bearing layer,the spectral decomposition technique can be used to effectively predict the gas layer's distribution.
