改进生态水利半径法可有效计算河流生态需水

改进减界在TI介正模拟的用张 慧,改进减界在TI介正模拟的用张 慧,李振春(中国石油大学(华东)地球资源与信息学院,山东青岛255666)[摘要]对边界的处理是正演模拟中很重要的部分,对各向异性介质来说,由于方程更复杂,独立弹性参数更多,所以边界处理也更为复杂针对传统的衰减边界条件,对其衰减因子进行改进,在同样宽度的减带情况下效果更好,并应用到复杂的各向异性介质正演模拟中通过数值模拟试验证明改进的衰减边界实施简单,在较薄的衰减带内能够较好的消除人工边界反射。[关键词]各向异性;边界处理;衰减边界;正演模拟[中图分类号]63144[文献标识码]A[文章编号]1009752(2010)002304限差分法演模拟地球物理非常流行,它能稳定处理各种杂模型,算效率也高但是在限差分正模拟中着两个固问题,一数值频散,二是边界射其中于在模拟将无限区域限化的做使得在工边界处生不期望反射,反能量返回计算区域过多次数积分不断积累,干扰了有效波识别,会记录造成定影响此,若想到一个成的模拟记录,消除边界射是必不少的步骤。过去的30年里,发展稳又高效的收边界条件是一个非常重要的问题关于各向同性介质弹性波程的吸收界条件已有较多的讨论,从最早的吸收边界条件由Lysmer和uhlemeyer提出后,不断展出新的法,例吸收边界[1]透射边界[2,3]衰减边界[4,5]。于各向异介质来说,方程更杂,独立性参数更多,导致边反射也更处理所在做各向异正演模拟时候需尽量避免设置边界件的时候入更多的杂性,故望选择一简单有效的法在对种边界件进行比后发现,减边界是个很有应价值的方法,它的最优点就是简单方便于实现,在这一点它要优于他的边界件但是方法的吸效果同其的方法相比不是特别出,为得到较好吸收效果常常需要置较厚的减带,极地增加了算量和计算存。上所述,向异性介质的正模拟中,何设置合的边界条以得到高量的地震录是一个亟解决的问题针对样的问题,笔者对传统的衰减边界条件进行改进,对erjan衰减因子进行了调整,实践证该方法仅可比传方法大幅升吸收效果,在大衰系数情况保持稳定,并且可以简植入到各复杂各异性介质波场模拟中,不需要外的处理者变换。1I介质性理论弹性介质中,根据义虎克定律,应力ij同应变ul和弹性常数cijkl有如下系:ij=ijklul(1)向各向同性(T)介质是具有柱对称轴的介质,根据对称轴在空间定向是垂直的还是水平的,为VTI介质和HTI质刚性阵包括12个弹参数,独参数有5个(根据Tomsen[6])各向异性质速力方程(Tingas[7];Juhlin[8])如下:[收日期]201002[基项目]家自科基项目(40974073);家863计划目(2006AA06206)。[作简介]慧(198),女,2006年学业,博士生,主从事震传和地成理与法方的究作。5ij=cijklvli,j,k,l=1,2,3(2)5t式中,v为速度同样,根据牛定律:ρ5vm=τ(3)m,n=5ij=cijklvli,j,k,l=1,2,3(2)5t式中,v为速度同样,根据牛定律:ρ5vm=τ(3)m,n=x,y,zmn5t式中为度式(2)和式(3)是度和应力量的一阶程组二维TI介一阶速度2应力方程为:ρ5vxxx xz= +5t5x 5zρ5vzxz zz= +5t5xx5x 5z5vx5vx5vz5vz=11+15+15+13(4)5t5zz5x5vx5z5vx5x5vz5z5vz=13+35+35+335t5xz5x5vx5z5vx5x5vz5z5vz=15+55+55+355t5x5z5x5z2改进的减边界件于各向异介质来说,由方程更复杂,独弹性参数多,以边界反也更难处理各同性边界条主要有吸边界条件透边界条件衰减边界条件3大类相比较而言,衰减边界条件是其中最简单也是容易实的一种衰减边也能够很的适应各异性介质边界处理。用得最普的衰减界条件是由erjan等人提出的[4]erjan通过在计算边界附近引入损耗介质来减向外传的波于在两个有不同吸系数的损介质的界上会产生射,这就求有较多的收层才能较好的吸收效果,而较多的吸收层意味着较大的计算量在erjan提出的方法中,引入尼项的波方程的和未加阻项的波动程的解之有如下关系:U(x,z,)=ep[-c(x,z)可视线性函数:c(x,z)=b(a-x)c(x,z)]1(x,z,t)(5)(6)式中,b衰减系数,可由验确定最值;a为吸收宽度这种离散型吸收边界是在吸收区域内使波的振幅指数衰减被吸收掉,从消除边界射。了常常需要较宽的吸收带外,在erjan的方法中,衰减因子是以指数形式表达的,指数衰相对不是特别稳定,不能简单的以加大衰减数的值来提高衰减效果,否则会在边界处出能量衰减过快导致的数值反射笔者在erjan衰减因子内增加一个新的衰减项,在大衰减数的情况下平缓指数衰减项,从而在同样宽吸收带情况下,取得相对较好较稳定的收果在方程(5)的衰减因子C(x,z)中添加衰项d(x,z)得。G(x,z)=epl(a-x)(7)d(x,z)图1不同衰减因子的衰减曲线了使能量在衰减带内部不出现明显数值反射,定义d(x,z)为:d(x,z)=d(x,z)x-r(8)234·石油天然气学报(江汉石油学院学报)2010年6月式中l,r为常数,x为网格点置d(0)234·石油天然气学报(江汉石油学院学报)2010年6月式中l,r为常数,x为网格点置d(0)=10图1为在减层为20的情况下,erjan衰减因子改进的衰减子对能量衰减强度在面的模型算中取r=1015。3 型试算立了2个度模型改进的边界条件的效果进行验证,第一个模型是均匀横向各向同性介质模型,二个是倾层速度型模型数和模拟数如表1示。表1正演模拟参数度型性数拟数/gcm-3序号位Δx/mz/m11/a33/a13/a55/a波类型t/ms率/z11011011011021511921511911411911411910191019161416141441251441251015121123克子波克子波3030注:Δxz分为型纵向格采间隔t为拟的间采间隔;113313和55是TI介的4个弹参数为密度。11均匀I介模型均匀各向性介质型进行了试验,比较erjan衰减边界改进的衰减边界和无边界条件的模拟结果图2(a)～(d)是使用erjan边界条件减带宽30时的波场记录和波场快照,图3(a)～(d)是使用了进的衰减界条件,减带宽为30时的波场记录和波场快照从波场记录和快照中可以看出:单独使用erjan边只能在吸收带较宽的情况下,边界反射才会被完全吸收,当吸收带较小时也出现边界射模使用了30个网的衰减带,但是仍然可以看到边界反射比较改进衰减边界处后的波场录和快照,看出边界吸收效果要好于erjan边界,这说明改进的边界条件在同样吸收带度的情况能取得对较好的果。图2经过衰减边界(扩边30)处理后的波场记录和波场快照12 倾斜向异性度模型型的第1和第3为各向同性介质,中间倾斜层为横向各向同性介质图4(a)和图4(b)分为600ms时刻X分和Z分的波场快照图4(c)和图4(d)分别为750ms时刻x量和z分量的场快照得到的结果(图4(a)～(d))看,波场快照上边界反射明显减弱,横波分裂现象清晰见,并且向同性介质一层的反射波能量明显比TI介质一层的反射波能量要弱,与Juhlin[8](1995年)得的结论一致倾斜层度模型证了改进衰减边界条件也适用于复杂的各向异性介质的正模拟。图3经过改进的衰减边界图3经过改进的衰减边界(扩边30)处理后的波场记录和波场快照图4倾斜各向异性介质的波场快照(600s和750)4结论减边界条适应性强,简单,于实现,常用的消人工边界射的方法该研究提的改进衰减界条件在种模型均取得了好的吸收果:1)保了衰减界条件的点,对其减因子进行改进,提升了衰减边界的吸收效果,经过广泛验证明,该方适用于种复杂各异性介质正演模拟。2)试的模型示对边界制效果较好,在大衰系数的情下比较稳定。[参考文献][1]laytonR,Engqist1Aboringoundaryonitonsforaousticandlasticwaeequatons[J]1Bl1i1o1A1,1977,67(6):1529～1541[2]廖鹏1近场动数模拟[J]1学进展,1997,27(2):193～211[3]igonR1Aboringoundaryonitonsforlasticwaes[J]1ophyics,1991,56(2):231241[4]Charleserjan,anolff,onieolff,eta1Aonrflectingoundaryonitonforicreteaousticandlasticwaeequatons[J]1ophyics,1985,50(4):705701[5]cciJ,ucekR,oreJ,t1AborigouaryoitonsadufeaesJ]1pycs,7,2():1[6]Tomen1eaklasticaiotopy[J]1ophyics,1986,51(10):19541961[7]TingasC,VfiisA,anaeichE1lasticwaepopagationintranserlyiotopiceiauingfiitefferences[J]1o2phyicalPopecting,1990,38(8):933～941[8]ChiopherJuli1fiitfferencelasticwaepopagationin2Dheteogenoustranserlyiotropiceia[J]1gophyicalpope2ting,1995,43(3):843～851[编辑]弘文oroverorover,anticlioriumandsynclioriumarearrangedalternatelyinthebasementocksofErlianBai1Therfore,Palaooicburiedillreeroirsmaybeoftheameieofistributonina51ag,itistheareaforfurthereplorato1eyrs:caronaterock;buriedill;ErlianBain;a51buriedillreeroir214anoyntfatnnnlealsfMltanoesLUin,Oi,NGheng,LUpeng,Noie(DepartmentofDevelopmentEnginee2ing,CNOOC,Langfang065201,Heei,Chin)act:Duringtheoifielddeelopmentbywateijecton,inlargcalechannelsandody,omeijectonandproductonwellsinthecertinlocatonswareonnectiity,wheretheonitonsofi2jectionandproduingwellswerepoo1Furtherstuiessowedthattherewasainlesandodyoundaryinsuchsandod1Basedonthatituation,tracingandlasfinginglechannelsan2odywasnecesaryforreogiingtheonnectiityrelatonwitinthemultsandoies,accuratelydeteriingthewaterijectonorinoingirectonofoiwaterwells,themetodwastostudyitbyuingtheliiteddataofwellloging,welltesting,oringandtrace1Themultsandoies,areclasfiedacoringtosandodypartitonanditsarealrelationsip1tslasfingprinipleisd2cribedanditisusedinXOifield,Thepeialoiwaterflowrulesofmeanderingchannelsandissummedp,bywichabaisisproidedformakingaplanofoifieldajustmen1eyrs:fluialfaies;multsandody;inlechannel217nrlactrsandLtfacesnreatnfroacederorsnhizira2tnfaniiasldUiasheg(SchoolofEnergyRsourcs,ChinaUnivesityofesciencs,Beijing100083,Chi2n)act:obetterunderstandtheontrollingfactorsandreseroiristributoninSihiorm2tonofDaiuiasieldinOrosBain,mathematicalstatisticmetodandregresonmetodwereeployedtostudytheontrolfactorsonthefaorablereeroirsinSiheiormatoninominatonwithtinsectonanalyis,grainizeanalyisandphyicalpropertyanalyi1twasonideredthatthegrinieandclasticonstituentswerethekeyfactorsontrollingthephyicalcharacteristicsofreseroir1Theoarsgrinedquartrichsandstonehadbetterphyicalpropertie1Aoringtowelltestandlogingdata,thequantitativereeroirisinterpretedinominatonwithgrainizeandopoito1ThesandstonearealistributonsowsthatellD1D2isafaorableeploratonare1eyrs:Daiuiasield;ontrolfactor;logingdata;litofaies;reseroirpreicton228ackieMatnnIeaandslatnNGJiai(RsearchIstituteofeologyandeophysis,ChinseAcademyofSciencs,Bei2jing100029,Chin)UNa(eophysicalRsearchIstituteofShengliOilfieldCompany,SINOPEC,Dongying257022,Shandong,Chin)NGhei,NGhancn(RsearchIstituteofeologyandeophysis,ChinseAcademyofSciencs,Beijing100029,Chin)act:Thealorithmsforonentonalprstacktimeigratonwerebasedontheassuptonthattheiituodelwasiotropicorlayerediotropicmeia,onentonallyusedtraetimealo2rithmswerestrightrayorbentraythories,anapproimatonthatwasoftenotalidandthusouldinducepoitonerrorsonNMOorigratonimage1ntispaper,thetraveltimealorithmswereuedinVTImeiaforprstacktimeigraton,andinominatonwiththesisicdataandstructuralcharacteristicsfromoplexountainareasintheortheastofichuanProincetofindanewmetodofprocesingtheimaingofisicdatafromtheoplexountinareasbyuingthetechiqueofprstacktimeigraton,proideanewawayforprocesingsisicdataforthei2larountinarea1eyrs:3Dsism;aiotropy;prstackimaing;sisicdataofoplexountinarea232latnfredapngonaryntnnIearardiatnNGi,LIhecn(Collegeof Information,ChinaUnivesityof Petroleum,Qingdao255666,Sha255666,Shandong,Chin)act:oundaryprocesingwaseryiportantinforwardodelin1oraiotropicmeia,waveequatonwasoreoplex,indpendentelasticparameterswouldbeore,therforethea2otropicmeiaodelingoundaryonitonswereorefficulttobehanledwit1Inalluontothetraitonaldapingoundaryoniton,itsdapingfactorsareiproedandtheoundaryo2itonobtinedcanbeusedinoplexaiotropicmeiaodelin1Thetestdeonstratesthattheiproeddapingoundaryonitioncaneliinatetheostoftheartfiialrflectonsintindapingone1eyrs:aiotropy;oundaryoniton;dapingoundary;forwardodeling240ckysalrortyanderorectnnLisuaafMangeesnLIia(ChinaUnivesityofMiningandTechnology,Beijing100083,Chin)act:BasedontheintegrationofmultwellloginginLishuwaDpreson,therockphyicalpropertyonkownwellswasstuied,thereseroirchangesundertheonitonsofwatercutandoilbearingwereobtinedthroughflidiplacementtes1Thefferenceofelasticreponseinreser2oirsoftheblockwasstuiedunderfferentsaturationonition1Onthebaisstatedaove,througharockphyicalforwardstudyandreeronoftheforwardresult,itisdeonstratedthatthereislessariatonofsandandmudeloityfferenceswithsperiposedlitology,theproblemofreseroirpreictoncanotbeffectielyoledbyposstackonstrainedparsepikereeroninthearea,itcanonlybeoledbyopresionalwaeeloityobtainedthroughjointprstackr2vero1eyrs:MiyangDpresion;forward;reveron;flidiplacement;reseroirpreicton248latnfcalcoostncnienolexaltlcka(GuangzhouInstituteofechemistry,ChinseAcademyofSciencs,GuangzhouNGPeng510640,Guangdong,China;BGPeologicalRsearchenter,Zhuozhou072751,Heei,Chin)NGJiaua(ChinaUnivesityofPetroleum,Dongying257061,Shandong,China;GuangzhouInstituteofechemistry,ChinseAcademyofSciencs,Guangzhou510640,Guangdong,Chin)NGonwei,NGSua,NPeng(BGPeologicalRsearchenter,Zhuozhou072751,H2ei,Chin)act:ointerpretfaultblocksinoplexfaultblockareasbyuingpectraldeopoitondataolumewasaveryffectietoo1Theworkingprinipleandinterpretingmetodofthepectrald2opoitonolumewereintroducedforinterpretatoninoplexfaultblockarea1Byuingthepectraldeopoitonphasecubelice,faultiagois,faultarealistributionarestuiedinpre2onstructuralinterpretationofcertinfaultblockareainazhoDpresion,bywichaveryoodresultisaciee1ey