Seismic Identification For The Sandstone Reservoir Of Nantun Formation In Beixi Area Of Hailar Basin

The main part of Beixi area consists of Huoduomoer structural belt,Sudeerte structural belt,Beixi sub-depression and Beixi slope zone of Bei'er Depression.the stratigraphic lithology of Nantun Formation is dominated by siltstone and salt-conglomerate.The physical property of reservoirs is poor,porosity and permeability are lower,and difference between non-reservoir and reservoir is relatively small in wave impedance.it's difficult to predict sandstone reservoir by using conventional inversion method.Because of the rapid facies changes of complex faulted-depression basin,vertical sandstone reservoir is developed,but single layer is thin,and the influence of seismic vertical resolution,it's difficult to identify single sandbody.Because of the influence of buried depth and surrounding rock,it's also difficult to select sensitive rockphysical parameters.In this paper,a technical method of seismic prediction is formed to deal with the geophysical problems and prediction difficulties of the reservoir of Nantun Formation,based on the rock physics analysis of well logging data,and then lithologic identification is improved through combining post-stack reservoir wave impedance inversion with post-stack de-compaction effects and the information of seismic effective bands is obtained as far as possible from the frequency expanded processing for high vertical resolution to further improve resolution of rock identification.Finally,Monte Carlo algorithm is adopted to carry out the sparse pulse inversion,combining constrained stochastic inversion,and vertical resolution is improved,which solves the identification difficulties of the ambiguity caused by lithology overlapping,the reservoir of 5-8m of Nantun Formation is effectively identifying,and a technical method and flow suitable for the prediction of the sandstone reservoirs in the area is formed.By Analyzes sandstone thickness and sand-shale ratio in sand interbed Formation of Nantun Formation,it's summarized to the plane distribution regularity of sand interbed Formation in first and second member of Nantun Formation.A tracing interpretation for the main oiled sandstone of Well Huo-12 and Huo-9 is completed,it's provided specific target for next exploration deployment.Finally,based on the analysis for the reservoir forming condition and controlling factor,and then the favorable reservoir is synthetical evaluated.