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1、基于貝葉斯理論的逐次迭代非線性AVA反演方法代榮獲張繁昌劉漢卿(中國石油大學(xué)(華東)地球科學(xué)與技術(shù)學(xué)院.青島.266580)摘要:常規(guī)AVA三參數(shù)反演方法均基于橫波速度與縱波速度之比為常數(shù)這一假設(shè)條件,且常被近似地取為0.5。然而在許多情況下并不為常數(shù),而是在橫向與縱向都漸變,若一概假定等于0.5,反演出的巖性參數(shù)勢必要偏離真實(shí)值,有必要合理地選擇。為此,本文基于貝葉斯理論,提出逐次迭代非線性AVA反演方法,該方法把看成橫向與縱向都漸變的反演初始背景,通過給定初始模型計(jì)算,并采用逐次迭代的策略求解該反演問題。從應(yīng)用效果分析來看,該方法合理地解決了關(guān)于的選取問題以及由于
2、引入變值而帶來的非線性問題,提高了AVA三參數(shù)反演結(jié)果的精確度;從抗噪性測試結(jié)果來看,該方法有著很好的穩(wěn)定性與優(yōu)良的抗噪性。作者簡介:代榮獲(1990-),男,碩士研究生,主要從事地球物理反演的研究工作?;痦?xiàng)目:國家科學(xué)自然基金(41374123)和國家973項(xiàng)目(2013CB228604)聯(lián)合資助關(guān)鍵詞:AVA反演;非線性;變縱橫波速度比;逐次迭代;貝葉斯理論Non-linearpre-stackseismicinversionbasedonBayesianTheoryusingSuccessiveiterationmethodDAIRonghuoZHANGFan
3、changLIUHanqing(SchoolofGeosciencesandTechnology,ChinaUniversityofPetroleum,Qingdao,266580,China)ABSTRACT:Conventionalthree-termAVAinversionmethodsarebasedontheassumptionthat(theratioofS-wavevelocitytoP-wavevelocity)isaconstant,anditisoftenconsideredtobe0.5,approximately.Inmanycases,iti
4、snotaconstantbutchangesgraduallybothinthehorizontalandvertical.Ifwealwaysassumethevalueofis0.5,theestimatedparametersoftheinversionisboundtodeviatefromitstruevalues.Itisnecessarytoselectreasonably.BasedonBayesiantheory,wepresentsanonlinearpre-stackseismicAVAinversionusingsuccessiveitera
5、tivemethod,whichconsiderstheratioasaninitialbackgroundandtheratiovaryingbothinhorizontalandverticaldirection.Calculatingtheinitialthroughagiveninitialmodel,wecanusesuccessiveiterationmethodtosolvethisnonlinearinversionproblem.Throughtheapplicationeffectanalysis,wecanseethatthismethodcan
6、takeareasonablesolutionfortheselectionofandsolvethenonlinearproblemthatisintroducedbyavariable.Atthesametime,itimprovestheaccuracyofthethree-termAVAinversion.Atlast,throughtakingananti-noisetest,itproofs13thatthemethodisfeasible,noiseresistent.Keywords:AVAinversion;nonlinear;variablerat
7、ioofS-velocitytoP-velocity;successiveiteration;Bayesiantheory1.引言基于疊前地震道集的反演技術(shù)在油田的勘探和開發(fā)中起著越來越重要的作用,其理論基礎(chǔ)是描述平面波在水平界面上反射與透射的Zoeppritz方程Error!Referencesourcenotfound.。基于Zoeppritz方程近似公式,常用的疊前地震反演分為兩種,一種是彈性阻抗反演Error!Referencesourcenotfound.,另一種是AVA三參數(shù)反演Error!Referencesourcenotfound.