Wang Weihua The Second Geological Survey Division, Bureau of oil Geophysical Prospecting, Kaifeng City, Henan Province, China, Internal postcode: 475002
Abstract:AVO technique has unique advantage in lateral prediction of hydrocarbon reservoir. However, low signal-to-noise ratio and thin-bed effect make very difficult the application of AVO technique in this field, AVO information extraction using correlation analysis removes quite well the unfavourable factor caused by low signal-to-noise ratio, avoiding the shortcoming of AVO technique. The method recommended here includes the following steps: &bull If F(θi) is the function which shows that the reflection amplitudes of NMO-corrected CDP gather near a well vary with incident angles, the theoretical CMP gather of reflection wave from gas-bearing sandstone bed near the well can be calculated in the light of the geological model which was constructed from logging data. &bull R(θi) curve for AVO analysis can be plotted by analysing its reflection amplitudes (or by inverion method). &bull ADO correlation coefficient section can be produced by correlating R(θi) curve with F(θi) curve of NMO-corrected CDP gather. &bull Lateral reservoir prediction can be achieved by analysing the distribution of highest correlation coefficients in the section. The example of gas-bearing sandstone at well No,wen-17 on seismic line No.323 in Zhongyuan oil field is taken to show the performance steps and application effect of this method.