弹性波阻抗理论和实现方法ppt课件

弹性阻抗理论 利用Hampson Russell软件实现弹性波阻抗反演 2020 4 20 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 2020 4 20 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 2020 4 20 道集 叠加 反演 AVO分析 属性1 属性2 估算VP VS 和 估算Z VP AVO方法同时使用多属性估算VP VS 和 可估算推测流体和岩性 2020 4 20 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 2020 4 20 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 2020 4 20 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 2020 4 20 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 2020 4 20 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 2020 4 20 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 2020 4 20 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 2020 4 20 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 2020 4 20 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 2020 4 20 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 2020 4 20 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 2020 4 20 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 2020 4 20 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 2020 4 20 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 2020 4 20 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 2020 4 20 CaseStudyfromtheColonySandPlayinAlberta Canada 2020 4 20 ApplyingElasticImpedancetotheColonyData Inthisexercise wewillstartwiththe2DColonydatasetwhichweanalyzedearlierandapplytheElasticImpedanceanalysistoit Firstre opentheavo classdatabaseinGEOVIEW OntheGEOVIEWwindow clickonDatabase Open Selectavo class wdbfromthepullDownlist asshown andclickonOK 2020 4 20 OntheGEOVIEWmainwindow clickontheAVO AVObuttontorestarttheAVOprogram SelecttheoptiontoOpenPreviousProjectandchoosethecolony prjproject 2020 4 20 Beforeanalyzingthedata wewillcreatetheelasticimpedancelogsinthemodelingwindow Ifitisnotvisible clickontheModeling SingleWellbuttononaseismicwindowandselectAVO WELLontheOpenWellmenutogetthefollowingwindow 2020 4 20 Next clickontheLogs Transformsbuttonasshownontheleft andselecttheElasticImpedanceoptionfromtheTransformsmenushownbelow 2020 4 20 ClickNext ontheTransformsmenuandselectthecorrectwell AVO WELL fortheP andS wavelogsandforstoringtheElasticImpedancelog asshownbelow 2020 4 20 Onthenextmenu makesuretheFRMeditedlogsareusedforthecalculationoftheelasticimpedanceandcalltheresultEI Nearasshown 2020 4 20 ClickonNext andfillinthenextmenuasshown choosingConstantAngleandfillinginanangleof7 5degrees 2020 4 20 WhentheEI Nearloghasbeencreated selecttheLogs Transformsoptionagain andfillinthemenusasshownpreviouslyexceptforthelasttwomenusshownhere Onthesemenus createanewlogcalledEI Far makingsurethattheFRMeditedlogsareusedinthecalculation ataconstantangleof22 5degrees 2020 4 20 Todisplaythetwoelasticimpedancetracestogether clickonthe eyeball icontobringuptheParametermenu UndertheLayouttab turnofftheDisplayOnlyActiveLogsbuttontoseeallofthelogs andputtheEI NearandtheEI Farlogsonthesametrack asshown 2020 4 20 ClickonOkandyouwillseethedisplaybelow NoticethattheEI Farlogplotstotheleftinthegaszoneandtotherightintherestofthelog Now let scrossplotthesetwologs 2020 4 20 ClickonCrossplotandfilloutthemenuasshownbelow selectingtheElasticImpedancelogtypeaswellasand Then clickonNext Onthismenu selectthewell andclickonNext 2020 4 20 Onthismenu selectElasticImpedanceforboththeXandYaxes andchangethePlotTitleasshownbelow Notethatwewillselectadifferentelasticimpedancelogforeachaxisonthenextmenu ClickonNext 2020 4 20 Onthismenu selectEI NearfortheXaxisandEI FarfortheYaxis asshown ClickonNext Onthismenu selectTimeasthedomain withstartandendvaluesof600and675 ClickonOktogetthecrossplot 2020 4 20 Noticethattheaxesoftheplotarebothlabeledthesame Tochangetheannotation clickonEdit Annotationsandchangethemenuasshownontheright ClickonOkandtheplotwillappearasshownontheleft Noticetheclearseparationofthepointsonthelowerleftoftheplot 2020 4 20 Letusnowperformzoneanalysistoseeiftheanomalyseenonthecrossplotreallyisthegassand Todothis firstdisplaythewelllogcurvesbyclickingontheCross Sectionbutton AfterusingtheZoomoption youshouldseeaplotsimilartothis 2020 4 20 Now clickontheZones Addoptionandcreatetheellipticalgreybackgroundtrendasshownontheright 2020 4 20 Nowdefinetheellipticalyellowgastrendasshown 2020 4 20 Notethattheplotofthewelllogshasbeenupdatedwiththecolors andtheanomalouspointsdoindeedcorrespondtothegassandzone 2020 4 20 NowgotothewindowcontainingtheoriginalCDPgathers ClickonProcess Stack RangeLimitedStack 2020 4 20 Usethedefaultsonthefirstmenuasshownontheright andclickonNext Then fillinthesecondmenuasshownontheleft Noticethatwearecreating2anglestacksfrom0to30degrees 2020 4 20 Thetwoanglestacksarecreatedasshownhere whererange limit stackisthenearanglestack andrange limit stack2isthefaranglestack 2020 4 20 Selectthefilecalledrange limit stack volfromthemenuandclickonOpen Next clickontheSTRATAbuttonontheGEOVIEWmainwindow Wewillcontinueusingthecolonyproject asindicatedinthemenuontheright ClickonOktobringuptheSTRATAmainwindow andthenclickonDataManager ImportData OpenSeismic OpenFromProject 2020 4 20 FillouttheWelltoSeismicMapmenuasshownandclickOk TheSTRATAwindownowlookslikethis 2020 4 20 ClickonHorizon PickHorizonsandpickasecondevent asshown Horizon1isthetroughatthetopofthegassand 2020 4 20 Finally pickathirdevent asshownhere ThenclickOktofinishthepicking 2020 4 20 Next clickonModel Build RebuildaModel Fillinthefirstpageasshownontheright changingtheoptionto TypicalsetupofElasticImpedanceforfar offsetstackinversion ClickonNext Onthethirdpage selectthewellAVO WELLandclickNext 2020 4 20 Onthenextpage wemustselecttheElasticImpedancelogwhichcorrespondstotheNearAnglestack Sincethisstackcoversananglerangeof0to15degrees chooseEI Near calculatedfortheangleof7 5degrees NowclickonNext twiceandOKtobuildthemodel Then clickonInvert ModelBasedasshown Onthefirstpage changetheoutputfilenametonear inversion ClickonNext twice Onthethirdpage changetheAverageBlockSizeto4 ClickOKtoruntheinversion 2020 4 20 Theinversionresultwilllooklikethis 2020 4 20 Next clickonWindow NewWindowtocreateanemptySTRATAwindow Inthisnewwindow clickonDataManager ImportData OpenSeismic OpenFromProjectandselectrange limit stack2 vol asshownontheright ClickonOpentogettheresultshownbelow Noticethattheexistingpicksareannotated 2020 4 20 Next clickonModel Build RebuildaModelandselecttheoptionTypicalsetupofElasticImpedanceforfar offsetstackinversiononthefirstpage asdonepreviously SelectAVO WELLonthethirdpageandchoosetheEI Farlog 22 5degrees onthefourth asshown Thenewmodelwilllooklikethis youmayneedtoupdatethecolorkey 2020 4 20 Next clickonInvert ModelBasedandchangethenameoftheoutputvolumeontheinversionmenuasshownbelow Onthethirdpage changetheAverageBlockSizeto4andclickonOKtostarttheinversionprocess 2020 4 20 Wenowhavetwoinversionresults Notethatwehavehadtousetwodifferentcolorscales sincetheimpedancevaluesarescaleddifferently Near inversion Far inversion 2020 4 20 Nowletuscomparethenear angleinversionwiththefar angleinversionbycross plottingthetwovolumes Oneitherofthetwoinversionresults clickonProcess CrossPlot Onthefirstmenupage selecttheCDPrangefrom300to360andthetwovolumesasshown ClickNext untilyoureachthefourthpage SpecifyaConstantTimeof630msasshown 2020 4 20 IftherewerenoAVOeffects wewouldexpectthefarandnearimpedancestoberelatedbyastraightline Inotherwords therewouldbeasinglecluster Let saddsomezonestothecrossplotandviewthecross sectiontoseewherethesezoneslie ClickonZones Add 2020 4 20 Makethefirstzoneusinganellipseandplaceitalongthemainaxis asshown PresstheApplybuttontosavethiszone 2020 4 20 Thenhighlightasecondzone aro