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The Prediction For Favorable Reservoir In Tight Clastic Rock At Xujiahe Formation Of The West Sichuan Depression In XC Structure

Posted on:2013-05-09Degree:MasterType:Thesis
Country:ChinaCandidate:Z SunFull Text:PDF
GTID:2230330377450025Subject:Earth Exploration and Information Technology
Abstract/Summary:PDF Full Text Request
With the developing of petroleum exploration, the exploration targets has alreadyturned from shallow layer to deep layer, from structural trap reservoir to lithologictrap reservoir, from conventional reservoirs with the high porosity and permeability tounconventional reservoirs like tight sandstone gas, coal seam gas, shale gas. Thedifficulty of exploration is gradually increasing.The Sichuan Basin is rich in a wealth of tight sandstone gas. But compact clasticreservoirs characterized by widely distributed, multi-layer system, thin alternatinglayers, strong, anisotropy, low porosity and permeability, complex formationpressure system, reservoir validity strongly depending on the degree of fracturedevelopment and complex features of the gas and water. Therefore it is extremelydifficult to identify favorable reservoirs by using conventional technical methods. Asa geophysics, petroleum engineering and geological cross-disciplinary and a bridge toconnect logging reservoir parameter prediction and seismic attribute analysis, is toanalyze the relationship of the rock physical properties. Specifically, it is a disciplinesof how to associate porosity and permeability with the seismic velocity, electricalresistivity, temperature and other parameters, which can provide more parameters andinformation for the interpretation of seismic data and effectively reduce the multiplesolutions of seismic inversion interpretation. So the rock physics is the foundation andthe test method of seismic data inversion and interpretation.This project intends to precise analysis of rock physics elastic parameters, summed up the elastic parameters of different lithology and fluid in Xujiaheformation of XC structure, and to build rock physic elastic parameters identificationplates and sensitive parameter table about important layer lithology, fluid identifiers.An irreplaceable bridge put up for favorable reservoir prediction and reservoir gasdetection by joint of well logging and seismic data. Rock physics can provide moreparameters and information for the interpretation of seismic data and effectivelyreduce the multiple solutions of seismic inversion interpretation.First, starting from the well data, we accurately calculate the percentage contentof the rock minerals, porosity, water saturation and other parameters. It is a well datapreparation for rock physics analysis. Seismic data is post-stack data, we need shearvelocity to do the rock physics analysis. Based on previous research results,Greenburg-Castagna method combined with VRH model is the optimal method topredict shear waves in the analysis of the actual situation on the background of lack ofshear wave logging data in Xujiahe formation on the study area. This method wasextended to the well without shear wave data, and achieved good results. The seismicrock physics analysis tool, fluid replacement, was used to do forward modelingstudies about reservoir seismic response to different gas saturation. We deduced thedetail calculation processes of fluid replacement and analyzed the correspondingvariation characteristics of rock physics parameters with the change in gas saturationin the reservoirs. Elastic impedance inversion theory was used to obtained elasticimpedance by different reflection angle from the logging data. The identificationmethods of multiple elastic parameters can fully exploit the inherent characteristics ofthe various elastic parameters, accurately and effectively identified the fluid andlithology. Finally, in the constraints of rock physics analysis, we used thepseudo-acoustic inversion, GR inversion and elastic multi-parameter inversion, toreduce the multiplicity of Solutions to accurately identify the favorable reservoir ofthe Xujiahe formation.
Keywords/Search Tags:tight sand, shear wave velocity prediction, fluid replacement, elastic parameter, elastic inversion
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