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弹性波阻抗理论和实现方法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.2023/11/3弹性波阻抗理论和实现方法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.2023/11/3弹性波阻抗理论和实现方法道集叠加反演AVO分析属性1属性2估算VP,VS,和

估算Z=

VPAVO方法

同时使用多属性估算VP,VS,和

,可估算推测流体和岩性.2023/11/3弹性波阻抗理论和实现方法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.2023/11/3弹性波阻抗理论和实现方法范围限制叠加道集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?2023/11/3弹性波阻抗理论和实现方法(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2023/11/3弹性波阻抗理论和实现方法这是近远偏移距(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2023/11/3弹性波阻抗理论和实现方法这是交绘图中的突出区块对应在剖面上的位置.可看出气砂岩已被很好地描绘.TopGASBaseGASCoal2023/11/3弹性波阻抗理论和实现方法(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)2023/11/3弹性波阻抗理论和实现方法

从范围限制叠加到弹性阻抗范围限制叠加使用的是常偏移距或常相位道集,方法很成熟并可避免同相轴未拉平问题.但它究竟有何含义?PatrickConnolly(BP),提出新颖的方法来解释范围叠加的含义,称之为弹性阻抗.弹性阻抗是基于Aki-Richards等式,下几张图片解释弹性阻抗的概念和由来.2023/11/3弹性波阻抗理论和实现方法弹性阻抗理论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:2023/11/3弹性波阻抗理论和实现方法假设

注意到我们可以把

Aki-Richards等式重写为:假设

K

为常数,可以将上式写为:2023/11/3弹性波阻抗理论和实现方法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:2023/11/3弹性波阻抗理论和实现方法

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:2023/11/3弹性波阻抗理论和实现方法将声阻抗(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2023/11/3弹性波阻抗理论和实现方法弹性阻抗–实例下图

显示声阻抗和弹性阻抗(30度角)的曲线比较:2023/11/3弹性波阻抗理论和实现方法 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:2023/11/3弹性波阻抗理论和实现方法EI

反演步骤道集AVO分析近角度叠加q1远角度叠加q2反演弹性阻抗

EI(q1)反演弹性阻抗

EI(q2)2023/11/3弹性波阻抗理论和实现方法CaseStudyfromtheColonySandPlayinAlberta,Canada2023/11/3弹性波阻抗理论和实现方法ApplyingElasticImpedancetotheColonyDataInthisexercise,wewillstartwiththe2DColonydatasetwhichweanalyzedearlierandapplytheElasticImpedanceanalysistoit.Firstre-opentheavo_classdatabaseinGEOVIEW.OntheGEOVIEWwindow,clickonDatabase/Open.Selectavo_class.wdbfromthepullDownlist,asshown,andclickonOK:2023/11/3弹性波阻抗理论和实现方法OntheGEOVIEWmainwindow,clickontheAVO/AVObuttontorestarttheAVOprogram:SelecttheoptiontoOpenPreviousProjectandchoosethecolony.prjproject:2023/11/3弹性波阻抗理论和实现方法Beforeanalyzingthedata,wewillcreatetheelasticimpedancelogsinthemodelingwindow.Ifitisnotvisible,clickontheModeling/SingleWellbuttononaseismicwindowandselectAVO_WELLontheOpenWellmenutogetthefollowingwindow:2023/11/3弹性波阻抗理论和实现方法Next,clickontheLogs/Transformsbuttonasshownontheleft,andselecttheElasticImpedanceoptionfromtheTransformsmenushownbelow:2023/11/3弹性波阻抗理论和实现方法ClickNext>>ontheTransformsmenuandselectthecorrectwell(AVO_WELL)fortheP-andS-wavelogsandforstoringtheElasticImpedancelog,asshownbelow.2023/11/3弹性波阻抗理论和实现方法Onthenextmenu,makesuretheFRMeditedlogsareusedforthecalculationoftheelasticimpedanceandcalltheresultEI_Nearasshown.2023/11/3弹性波阻抗理论和实现方法ClickonNext>>andfillinthenextmenuasshown,choosingConstantAngleandfillinginanangleof7.5degrees.2023/11/3弹性波阻抗理论和实现方法WhentheEI_Nearloghasbeencreated,selecttheLogs/Transformsoptionagain,andfillinthemenusasshownpreviouslyexceptforthelasttwomenusshownhere.Onthesemenus,createanewlogcalledEI_Far(makingsurethattheFRMeditedlogsareusedinthecalculation)ataconstantangleof22.5degrees.2023/11/3弹性波阻抗理论和实现方法Todisplaythetwoelasticimpedancetracestogether,clickonthe“eyeball”icontobringuptheParametermenu.UndertheLayouttab,turnofftheDisplayOnlyActiveLogsbuttontoseeallofthelogs,andputtheEI_NearandtheEI_Farlogsonthesametrack,asshown.2023/11/3弹性波阻抗理论和实现方法ClickonOkandyouwillseethedisplaybelow.NoticethattheEI_Farlogplotstotheleftinthegaszoneandtotherightintherestofthelog.Now,let’scrossplotthesetwologs.2023/11/3弹性波阻抗理论和实现方法ClickonCrossplotandfilloutthemenuasshownbelow,selectingtheElasticImpedancelogtypeaswellas<VerticalDepth>and<Time>.Then,clickonNext>>.Onthismenu,selectthewell,andclickonNext>>.2023/11/3弹性波阻抗理论和实现方法Onthismenu,selectElasticImpedanceforboththeXandYaxes,andchangethePlotTitleasshownbelow.(Notethatwewillselectadifferentelasticimpedancelogforeachaxisonthenextmenu).ClickonNext>>.2023/11/3弹性波阻抗理论和实现方法Onthismenu,selectEI_NearfortheXaxisandEI_FarfortheYaxis,asshown.ClickonNext>>.Onthismenu,selectTimeasthedomain,withstartandendvaluesof600and675.ClickonOktogetthecrossplot.2023/11/3弹性波阻抗理论和实现方法

Noticethattheaxesofthe plotarebothlabeledthe same.Tochangetheannotation,clickonEdit/Annotationsandchangethemenuasshownontheright:ClickonOkandtheplotwillappearasshownontheleft.Noticetheclearseparationofthepointsonthelowerleftoftheplot.2023/11/3弹性波阻抗理论和实现方法Letusnowperformzoneanalysistoseeiftheanomalyseenonthecrossplotreallyisthegassand.Todothis,firstdisplaythewelllogcurvesbyclickingontheCross-Sectionbutton.AfterusingtheZoomoption,youshouldseeaplotsimilartothis:2023/11/3弹性波阻抗理论和实现方法Now,clickontheZones/Addoptionandcreatetheellipticalgreybackgroundtrendasshownontheright.2023/11/3弹性波阻抗理论和实现方法Nowdefinetheellipticalyellowgastrendasshown.2023/11/3弹性波阻抗理论和实现方法Notethattheplotofthewelllogshasbeenupdatedwiththecolors,andtheanomalouspointsdoindeedcorrespondtothegassandzone.2023/11/3弹性波阻抗理论和实现方法NowgotothewindowcontainingtheoriginalCDPgathers.ClickonProcess/Stack/RangeLimitedStack:2023/11/3弹性波阻抗理论和实现方法Usethedefaultsonthefirstmenuasshownontheright,andclickonNext>>.Then,fillinthesecondmenuasshownontheleft.Noticethatwearecreating2anglestacksfrom0to30degrees.2023/11/3弹性波阻抗理论和实现方法Thetwoanglestacksarecreatedasshownhere,whererange_limit_stackisthenearanglestack,andrange_limit_stack2isthefaranglestack.2023/11/3弹性波阻抗理论和实现方法Selecttherange_limit_stack.volfromthemenuandclickonOpen.Next,clickontheSTRATAbuttonontheGEOVIEWmainwindow.Wewillcontinueusingthecolonyproject,asindicatedinthemenuontheright.ClickonOktobringuptheSTRATAmainwindow,andthenclickonDataManager/ImportData/OpenSeismic/OpenFromProject.2023/11/3弹性波阻抗理论和实现方法FillouttheWelltoSeismicMapmenuasshownandclickOk.TheSTRATAwindownowlookslikethis:2023/11/3弹性波阻抗理论和实现方法ClickonHorizon/PickHorizonsandpickasecondevent,asshown.Horizon1isthetroughatthetopofthegassand.2023/11/3弹性波阻抗理论和实现方法Finally,pickathirdevent,asshownhere.ThenclickOktofinishthepicking.2023/11/3弹性波阻抗理论和实现方法Next,clickonModel/Build/Rebuild

aModel.Fillinthefirstpageasshownontheright,changingtheoptionto:TypicalsetupofElasticImpedanceforfar-offsetstackinversion.ClickonNext>>.Onthethirdpage,selectthewellAVO_WELLandclickNext>>.2023/11/3弹性波阻抗理论和实现方法Onthenextpage,wemustselecttheElasticImpedancelogwhichcorrespondstotheNearAnglestack.Sincethisstackcoversananglerangeof0to15degrees,chooseEI_Near,calculatedfortheangleof7.5degrees.NowclickonNext>>twiceandOKtobuildthemodel.Then,clickonInvert/ModelBasedasshown:Onthefirstpage,changetheoutputtonear_inversion.ClickonNext>>twice.Onthethirdpage,changetheAverageBlockSizeto4.ClickOKtoruntheinversion.2023/11/3弹性波阻抗理论和实现方法Theinversionresultwilllooklikethis:2023/11/3弹性波阻抗理论和实现方法

Next,clickonWindow/New Windowtocreateanempty STRATAwindow.Inthisnew window,clickonDataManager/ImportData/OpenSeismic/OpenFromProjectandselectrange_limit_stack2.vol,asshownontheright.ClickonOpentogettheresultshownbelow.Noticethattheexistingpicksareannotated.2023/11/3弹性波阻抗理论和实现方法

Next,clickonModel/Build/Rebuilda ModelandselecttheoptionTypicalsetup ofElasticImpedanceforfar-offsetstack inversiononthefirstpage,asdonepreviously.SelectAVO_WELLonthethirdpageandchoosetheEI_Farlog(22.5degrees)onthefourth,asshown.Thenewmodelwilllooklikethis(youmayneedtoupdatethecolorkey):2023/11/3弹性波阻抗理论和实现方法Next,clickonInvert/ModelBasedandchangethenameoftheoutputvolumeontheinversionmenuasshownbelow.Onthethirdpage,changetheAverageBlockSizeto4andclickonOKtostarttheinversionprocess:2023/11/3弹性波阻抗理论和实现方法Wenowhavetwoinversionresults.Notethatwehavehadtousetwodifferentcolorscales,sincetheimpedancevaluesarescaleddifferently.Near_inversionFar_inversion2023/11/3弹性波阻抗理论和实现方法Nowletuscomparethenear-angleinversionwiththefar-angleinversionbycross-plottingthetwovolumes.Oneitherofthetwoinversionresults,clickonProcess/CrossPlot:Onthefirstmenupage,selecttheCDPrangefrom300to360andthetwovolumesasshown:ClickNext>>untilyoureachthefourthpage.SpecifyaConstantTimeof630msasshown:2023/11/3弹性波阻抗理论和实现方法IftherewerenoAVOeffects,wewouldexpectthefarandnearimpedancestoberelatedbyastraightline.Inotherwords,therewouldbeasinglecluster.Let’saddsomezonestothecrossplotandviewthecross-sectiontoseewherethesezoneslie.ClickonZones/Add:2023/11/3弹性波阻抗理论和实现方法Makethefirstzoneusinganellipseandplaceitalongthemainaxis,asshown.PresstheApplybuttontosa