Angle-dependent seismic attenuation based gas-bearing detection of sandstone river channel reservoir in western Sichuan Basin

The shallow river channel sandstone reservoirs of Jurassic in the western Sichuan Basin are rich in natural gas. The gas-bearing sweet-spot has a ‘sausage-like’ distribution feature, with complex gas water distribution. Analyses of seismic data at different angles show that gas-bearing reservoir formation has different seismic attenuation features from the water-bearing formations, and such differences have a certain correlation with gas production. Accordingly, a gas-bearing detection technology based on angle-dependent seismic attenuation feature is proposed. First, the matching-pursuit time-frequency analysis method is used to extract high-resolution time-frequency spectra from seismic data at different incidence angles. Then, the angle-dependent seismic attenuation attribute is estimated using the extracted time-frequency spectra. Finally, the attribute is combined with the inverted impedance for gas-bearing detection. With the advantages of lower uncertainty and being less affected by reservoir porosity, the application results of the developed method have a high coincidence rate with the drilled wells, and the drilling wells deployed based on the detection results have achieved high production.