Seismic Facies Analysis And Reservoir Prediction Of The Shiniulan Formation In The Southeastern Sichuan Basin

To further ascertain the exploration potential of Silurian strata in Southeast Sichuan,based on the investigation of field section,logging-seismic data and guided by multi-theories like sedimentary geology and seismic exploration,this paper target the Shiliulan formation carbonatite,report the seismic facies analysis and reservoir prediction of the Shiliulan formation in Southeast Sichuan,and the comprehensive analysis of the potential exploration zone in study area.The following conclusions are drawn from the analysis:(1)The Shiliulan formation has developed the carbonate platform-continental shelf sedimentary systems;it can divide to four subfacies and nine microfacies.(2)There are four types of seismic facies in the study area.Type I is continuous sill-like seismic facies;type II is intermittent subparallel weak-median-amplitude seismic facies;type III is intermittent-continuous,high-frequency weak-amplitude seismic facies;type IV develop the oblique progradation configuration.Type II is the main seismic facies in the study area and type II,IV is the advantageous seismic facies of reservoir development.The analysis of seismic facies can helped us further understanding the plane distribution of sedimentary facies.(3)Based on the logging response characteristics and the seismic response characteristics,the geophysics response anaysis of the Shiniulan formation are following: the gas layers of the Shiniulan formation are different types and have different velocity,generally they have high-velocity and low-gamma value;the seismic response shows that the high-amplitude value of the top-bottom valley in the Shiniulan formation reflect the development of the high-velocity limestone,and the low value show the development of low-velocity mudstone.(4)Based on the geophysics response characteristics we extract suitable seismic attributions of the Shiliulan formation,e.g.top-strata average peak amplitude,second-phase average peak amplitude and average instantaneous frequency.They show the development of reservoir and the oil-gas possibility;subsequently we built the precise time-depth relationship and analyze the lithology-electric sensitivity,adopt the wave impedance inversion to predict reservoirs.The result shows the plane distribution of the high-velocity limestone and mudstone.(5)By the combination of all the findings and the evaluation of reservoirs,we delineate the potential exploration area into three classes,each class have two areas.