弹性波阻抗理论和实现方法课件

弹性阻抗理论Hampson-Russell软件实现弹性波阻抗反演2022/12/19弹性阻抗介绍先回顾弹性阻抗反演的原理,然后利用Hampson-Russell一组软件分析弹性阻抗反演一个实际例子.弹性阻抗ElasticImpedance

(EI)

是由BP公司PatrickConnolly提出.实现弹性阻抗反演可用AVO和STRATA软件自然组合来完成.在谈论弹性阻抗反演之前,简单回顾反演方法在地震勘探运用的历史.2022/12/19弹性阻抗CDP/CRP道集迭加反演估算Z=VP地震岩性估算传统的地震岩性估算是在地震数据叠加偏移后数据(叠后数据)道进行反演.这只能估算声阻抗,不足于推测流体成分.2022/12/19弹性阻抗AVO分析可能用的属性但是哪两种(或更多属性)可用来最好地预测流体和岩性这些参数?目前AVO可提取和使用的一系列不同属性:

偏移距或角度段限(范围限制)叠加

弹性阻抗反演

截距和梯度

提取的纵横波反射系数RP,RS

由RP

和RS

反演到纵横波阻抗ZP,ZS

纵横波阻抗ZP,ZS

转换Lambda-Mu-Rho分析本讨论先使用前面两个属性的方法.后面再讨论其它的属性方法.2022/12/19弹性阻抗范围限制叠加道集AVO分析近叠加远叠加以上是范围限制叠加的简单流程.利用常偏移距或常角度的范围叠加已经非常成熟.问题是如何解释其结果?2022/12/19弹性阻抗(a)(b)近角度(0o-15o)叠加远角度(15o-30o)叠加数据来自加拿大Colony区块.在630MS有一个“亮点”震幅在远角度

叠加上比近角度叠加要强的多.从井资料分析这是气砂岩导致“亮点”.气砂岩范围限制叠加2022/12/19弹性阻抗这是近远偏移距(角度)的交绘图,高震幅区块用不同颜色突出显示.角度叠加进行交绘图2022/12/19弹性阻抗(a)近角度叠加(0-15o)时间切片,(b)远角度叠加

(15-30o)时间切片(三维河道砂).对时间切片震幅包络求得是10MS窗口内的平均值并运用了Z-SCORE转换.异常河道砂得以清楚显示.角度范围叠加(a)(b)2022/12/19弹性阻抗弹性阻抗理论Aki-Richards等式可写为(三项式):Connolly(1999)提出,类似于声阻抗,我们定义弹性阻抗(EI)

为:2022/12/19弹性阻抗然后进行积分和取幂,可得到以下弹性阻抗

EI等式:

如果

=0o,EI弹性阻抗就还原为声阻抗(AI),等式为:2022/12/19弹性阻抗

以上等式使用的是Aki-Richards所有三项等式.对于入射角大于300,该等式将不是线性的拟合.对于大角度(大偏移距),如果只用等式的前两项,等式可写为:

当

=0o,得到:2022/12/19弹性阻抗将声阻抗(AI)转换入射角为30°的弹性阻抗通常曲线类似但阻抗绝对值变低.角度增加其视声波阻抗降低.油砂岩比页岩视声波阻抗降低幅度更大.如下图Connolly1999弹性阻抗–油饱和度的影响2022/12/19弹性阻抗弹性阻抗–实例下图

显示声阻抗和弹性阻抗(30度角)的曲线比较:2022/12/19弹性阻抗 重叠显示更好地区分弹性阻抗和声阻抗在含油砂岩处的差别:2022/12/19弹性阻抗CaseStudyfromtheColonySandPlayinAlberta,Canada2022/12/19弹性阻抗ApplyingElasticImpedancetotheColonyDataInthisexercise,wewillstartwiththe2DColonydatasetwhichweanalyzedearlierandapplytheElasticImpedanceanalysistoit.Firstre-opentheavo_classdatabaseinGEOVIEW.OntheGEOVIEWwindow,clickonDatabase/Open.Selectavo_class.wdbfromthepullDownlist,asshown,andclickonOK:2022/12/19弹性阻抗Beforeanalyzingthedata,wewillcreatetheelasticimpedancelogsinthemodelingwindow.Ifitisnotvisible,clickontheModeling/SingleWellbuttononaseismicwindowandselectAVO_WELLontheOpenWellmenutogetthefollowingwindow:2022/12/19弹性阻抗Next,clickontheLogs/Transformsbuttonasshownontheleft,andselecttheElasticImpedanceoptionfromtheTransformsmenushownbelow:2022/12/19弹性阻抗Onthenextmenu,makesuretheFRMeditedlogsareusedforthecalculationoftheelasticimpedanceandcalltheresultEI_Nearasshown.2022/12/19弹性阻抗ClickonNext>>andfillinthenextmenuasshown,choosingConstantAngleandfillinginanangleof7.5degrees.2022/12/19弹性阻抗WhentheEI_Nearloghasbeencreated,selecttheLogs/Transformsoptionagain,andfillinthemenusasshownpreviouslyexceptforthelasttwomenusshownhere.Onthesemenus,createanewlogcalledEI_Far(makingsurethattheFRMeditedlogsareusedinthecalculation)ataconstantangleof22.5degrees.2022/12/19弹性阻抗ClickonOkandyouwillseethedisplaybelow.NoticethattheEI_Farlogplotstotheleftinthegaszoneandtotherightintherestofthelog.Now,let’scrossplotthesetwologs.2022/12/19弹性阻抗ClickonCrossplotandfilloutthemenuasshownbelow,selectingtheElasticImpedancelogtypeaswellas<VerticalDepth>and<Time>.Then,clickonNext>>.Onthismenu,selectthewell,andclickonNext>>.2022/12/19弹性阻抗Onthismenu,selectElasticImpedanceforboththeXandYaxes,andchangethePlotTitleasshownbelow.(Notethatwewillselectadifferentelasticimpedancelogforeachaxisonthenextmenu).ClickonNext>>.2022/12/19弹性阻抗Onthismenu,selectEI_NearfortheXaxisandEI_FarfortheYaxis,asshown.ClickonNext>>.Onthismenu,selectTimeasthedomain,withstartandendvaluesof600and675.ClickonOktogetthecrossplot.2022/12/19弹性阻抗

Noticethattheaxesofthe plotarebothlabeledthe same.Tochangetheannotation,clickonEdit/Annotationsandchangethemenuasshownontheright:ClickonOkandtheplotwillappearasshownontheleft.Noticetheclearseparationofthepointsonthelowerleftoftheplot.2022/12/19弹性阻抗Letusnowperformzoneanalysistoseeiftheanomalyseenonthecrossplotreallyisthegassand.Todothis,firstdisplaythewelllogcurvesbyclickingontheCross-Sectionbutton.AfterusingtheZoomoption,youshouldseeaplotsimilartothis:2022/12/19弹性阻抗Now,clickontheZones/Addoptionandcreatetheellipticalgreybackgroundtrendasshownontheright.2022/12/19弹性阻抗Nowdefinetheellipticalyellowgastrendasshown.2022/12/19弹性阻抗Notethattheplotofthewelllogshasbeenupdatedwiththecolors,andtheanomalouspointsdoindeedcorrespondtothegassandzone.2022/12/19弹性阻抗NowgotothewindowcontainingtheoriginalCDPgathers.ClickonProcess/Stack/RangeLimitedStack:2022/12/19弹性阻抗Usethedefaultsonthefirstmenuasshownontheright,andclickonNext>>.Then,fillinthesecondmenuasshownontheleft.Noticethatwearecreating2anglestacksfrom0to30degrees.2022/12/19弹性阻抗Thetwoanglestacksarecreatedasshownhere,whererange_limit_stackisthenearanglestack,andrange_limit_stack2isthefaranglestack.2022/12/19弹性阻抗Selecttherange_limit_stack.volfromthemenuandclickonOpen.Next,clickontheSTRATAbuttonontheGEOVIEWmainwindow.Wewillcontinueusingthecolonyproject,asindicatedinthemenuontheright.ClickonOktobringuptheSTRATAmainwindow,andthenclickonDataManager/ImportData/OpenSeismic/OpenFromProject.2022/12/19弹性阻抗FillouttheWelltoSeismicMapmenuasshownandclickOk.TheSTRATAwindownowlookslikethis:2022/12/19弹性阻抗ClickonHorizon/PickHorizonsandpickasecondevent,asshown.Horizon1isthetroughatthetopofthegassand.2022/12/19弹性阻抗Finally,pickathirdevent,asshownhere.ThenclickOktofinishthepicking.2022/12/19弹性阻抗Next,clickonModel/Build/Rebuild

aModel.Fillinthefirstpageasshownontheright,changingtheoptionto:TypicalsetupofElasticImpedanceforfar-offsetstackinversion.ClickonNext>>.Onthethirdpage,selectthewellAVO_WELLandclickNext>>.2022/12/19弹性阻抗Onthenextpage,wemustselecttheElasticImpedancelogwhichcorrespondstotheNearAnglestack.Sincethisstackcoversananglerangeof0to15degrees,chooseEI_Near,calculatedfortheangleof7.5degrees.NowclickonNext>>twiceandOKtobuildthemodel.Then,clickonInvert/ModelBasedasshown:Onthefirstpage,changetheoutputtonear_inversion.ClickonNext>>twice.Onthethirdpage,changetheAverageBlockSizeto4.ClickOKtoruntheinversion.2022/12/19弹性阻抗Theinversionresultwilllooklikethis:2022/12/19弹性阻抗

Next,clickonWindow/New Windowtocreateanempty STRATAwindow.Inthisnew window,clickonDataManager/ImportData/OpenSeismic/OpenFromProjectandselectrange_limit_stack2.vol,asshownontheright.ClickonOpentogettheresultshownbelow.Noticethattheexistingpicksareannotated.2022/12/19弹性阻抗

Next,clickonModel/Build/Rebuilda ModelandselecttheoptionTypicalsetup ofElasticImpedanceforfar-offsetstack inversiononthefirstpage,asdonepreviously.SelectAVO_WELLonthethirdpageandchoosetheEI_Farlog(22.5degrees)onthefourth,asshown.Thenewmodelwilllooklikethis(youmayneedtoupdatethecolorkey):2022/12/19弹性阻抗Next,clickonInvert/ModelBasedandchangethenameoftheoutputvolumeontheinversionmenuasshownbelow.Onthethirdpage,changetheAverageBlockSizeto4andclickonOKtostarttheinversionprocess:2022/12/19弹性阻抗Wenowhavetwoinversionresults.Notethatwehavehadtousetwodifferentcolorscales,sincetheimpedancevaluesarescaleddifferently.Near_inversionFar_inversion2022/12/19弹性阻抗Nowletuscomparethenear-angleinversionwiththefar-angleinversionbycross-plottingthetwovolumes.Oneitherofthetwoinversionresults,clickonProcess/CrossPlot:Onthefirstmenupage,selecttheCDPrangefrom300to360andthetwovolumesasshown:ClickNext>>untilyoureachthefourthpage.SpecifyaConstantTimeof630msasshown:2022/12/19弹性阻抗IftherewerenoAVOeffects,wewouldexpectthefarandnearimpedancestoberelatedbyastraightline.Inotherwords,therewouldbeasinglecluster.Let’saddsomezonestothecrossplotandviewthecross-sectiontoseewherethesezoneslie.ClickonZones/Add:2022/12/19弹性阻抗Makethefirstzoneusinganellipseandplaceitalongthemainaxis,asshown.PresstheApplybuttontosavethiszone.2022/12/19弹性阻抗Thenhighlightasecondzone,aroundtheclusterasshown:PresstheApplybuttontosa