頻譜整形技術(shù)的計(jì)算機(jī)模擬研究

1、頻譜整形技術(shù)的計(jì)算機(jī)模擬研究袁子龍(安達(dá)大慶石油學(xué)院)幺景臣(盤錦遼河石油勘探局研究院)袁子龍 幺景臣: 頻譜整形技術(shù)的計(jì)算機(jī)模擬研究, 石油儀器, 1997, 11 (5) , 34 36, 61。摘要 地層的高頻吸收衰減效應(yīng)是導(dǎo)致地震勘探分辨率不高的主要原因, 在高分辨率野外地震數(shù)據(jù)采集系統(tǒng)中, 頻譜整形濾波器 (ssf ) 是所設(shè)置的重要部件。 文章討論了地層吸收衰減與地震波的傳播距離、頻率、時(shí)間和介質(zhì)波速的關(guān)系; 用計(jì)算機(jī)模擬的方法研究地層吸收衰減使分辨率降低的程度和 ssf 對(duì)高頻信號(hào)的補(bǔ)償效果, 指出 了 ssf 對(duì)分辨率的補(bǔ)償量只占由于地層吸收衰減而導(dǎo)致分辨率降低量的 42. 5

2、 % 左右。主 題 詞 地震勘探 地層吸收 高分辨率 頻譜 整形濾波作者介紹 袁子龍 副教授, 1961 年生, 1994 年畢業(yè)于大慶石油學(xué)院應(yīng)用地球物理專業(yè)獲碩士學(xué)位。 現(xiàn)在大慶石 油學(xué)院勘探系物探教研室, 從事儀器理論研究與電路設(shè)計(jì)、高分辨率地震勘探研究、儲(chǔ)層預(yù)測(cè)研究及教學(xué)工作。 郵編: 151400度 v v 有直接關(guān)系。品質(zhì)因數(shù) q是巖石對(duì)彈性波的前言吸收特性一種表達(dá)方式, 它是耗散能 % 與儲(chǔ)能 e的 比率, 表達(dá)式為地層的高頻吸收衰減效應(yīng)是導(dǎo)致地震勘探分辨率不高的主要原因, 高分辨率地震勘探要求其數(shù)據(jù) 采集系統(tǒng)具有較大的瞬時(shí)動(dòng)態(tài)范圍和系統(tǒng) 動(dòng) 態(tài) 范圍。 為此, 在高分辨率地震勘

3、探的數(shù)據(jù)采集中, 設(shè)置了 24 位 a d 轉(zhuǎn)換器和頻譜整形濾波器 (ssf )。設(shè) 置 24 位 a d 轉(zhuǎn)換器只對(duì)擴(kuò)大儀器的瞬時(shí)動(dòng)態(tài)范圍 有好處, 可使有效的瞬時(shí)動(dòng)態(tài)范圍擴(kuò)大到 114 db。設(shè)置 ssf 不僅可以擴(kuò)大儀器的瞬時(shí)動(dòng)態(tài)范圍, 更重 要的是可以彌補(bǔ)地層對(duì)高頻的吸收衰減效應(yīng)和擴(kuò)大儀器的系統(tǒng)動(dòng)態(tài)范圍, 提高高頻信號(hào)的信噪比, 有效 提高了地震勘探的分辨率。 %(v v ) 2. 2(2)q =142%其中 e 是處于最大應(yīng)力和應(yīng)變狀態(tài)下的彈性能; %是 諧 波 每 振 動(dòng) 一 個(gè) 周 期 的 能 量 損 耗。其 中 v v 以km s 為單位。將 q = 代入式 (2) , 可以推

4、導(dǎo)出 的表達(dá)式為 (3)=14 (v v )2. 2將式 (3) 代入式 (1) 得到式 (4)r-a = a o r ( t) r e2. 2(4)14 (v v )因?yàn)?r =v v r t, = v v f , 所以式 (4) 可變換為 0. 224 f t-a = a o r ( t) r e2. 2(5)(v v )地層吸收衰減效應(yīng)1由 式 ( 5) 可以看出: 反射界面埋藏越深, 地層對(duì)波的吸收越嚴(yán)重; 在反射波的各頻率分量中, 頻率越 高, 地層對(duì)其吸收越嚴(yán)重; 地震波的傳播速度越低, 地層對(duì)波的吸收越嚴(yán)重。 針對(duì)某一特定地區(qū)和某一確定層位, 時(shí)間深度 t 和速度 v v 均是常

5、數(shù), 這時(shí)式(5) 只反映了波的頻率越高, 地層對(duì)其吸收越嚴(yán)重。 某一地區(qū)的 v o = 1 880 m s, = 0. 000 26m , 取時(shí)間深度 t= 2. 0 s, 則平均速度為2在均勻吸收介質(zhì)中傳播的平面波振幅方程為a = a o r ( t) r e2r(1)其中, a o 為初始振幅; ( t) 為波動(dòng)函數(shù); 為吸收系數(shù), r 為平面波傳播的距離。 當(dāng)把地層看作均勻介質(zhì)時(shí), 其介質(zhì)的速度為地層 的平均速度 v v , 介質(zhì)對(duì)地震波的吸收與地層速v o tv v = 2 e1 = 2 424 m s2 -t所以式 (5) 可變換為20. 063 9 fa = a o ( t) e

6、(6)則地層的吸收衰減因子可表示為d = e20. 063 9 f(7)地層吸收衰減效應(yīng)對(duì)地震分辨率影響的計(jì)算機(jī)模擬分析建立具有一個(gè)反射面的簡(jiǎn)單地質(zhì)模型如圖 1 所示。圖 1 均勻吸收地質(zhì)模型選擇 f o = 30 h z 零相位雷克子波為地震子波, 若不 考慮地層吸收衰減效應(yīng), 則分辨率不會(huì)降低, 反射波圖 3地層吸收衰減與頻譜整形技術(shù)的計(jì)算機(jī)模擬流程( t)和振幅譜 f (f )的時(shí)間域波形 f如圖 2 所示。圖 4 有地層吸收衰減情況下的地震響應(yīng)y 1 ( t) 和振幅譜 y 1 (f ) 如圖 4 所示。由圖 2 和圖 4 的 振幅譜對(duì)比可以看出, 反射波的主頻率由 30 h z 降低

7、為 f 1 = 18 h z, 所以可分辨的地層最小厚度為圖 2 無(wú)地層吸收衰減情況下的地震響應(yīng)可分辨的地層最小厚度為v v = 20. 20 mv vz o =4 =z 1 = 33. 67 m4 f o4 f 1分辨率 r 與可分辨地層的最小厚度 z 成反比,比例系數(shù)為 p , 則上述種情況下的分辨率為考慮到地層吸收衰減效應(yīng), 用計(jì)算機(jī)對(duì)此進(jìn)行正演模擬, 其流程如圖 3 所示。所獲得的地震反射波r o = p z o r 1 = p z 1由于地層吸收衰減效應(yīng)使分辨率降低的百分?jǐn)?shù)為表 1 地層吸收和 io sy stem ssf補(bǔ)償 (v v = 2 424 m s, t= 2. 0 s)

8、r 1 1 1r o 100 %= zo (-) 100 % = 40 %z oz 1io sy stem 數(shù)控地震儀 ssf對(duì)分辨率的改善在起始頻率到終了頻率之間, 頻譜整形濾波器圖 6 地層吸收與 ssf 補(bǔ)償對(duì)比經(jīng)過(guò)地層傳輸以后, 地震信號(hào)的高頻成分損失嚴(yán)重, 使分辨率降低, 頻譜整形濾波器對(duì)高頻信息給 一定的補(bǔ)償, 使分辨率有一定提高, 其計(jì)算機(jī)正演模 擬過(guò)程也體現(xiàn)在圖 3 中。 頻譜整形以后地震反射波y 2 ( t) 和 y 2 (f ) 如圖 5 所示。圖 5io sy stem ssf 頻譜整形后的地震響應(yīng)其反射波的主頻率由 18 h z 提高到 f 2 = 23 h z,分辨的

9、地層最小厚度為可的增益隨頻率的升高而增大, 頻率提升速率為每倍頻程 6 db 3 , 頻譜整形系數(shù)的振幅譜和相位譜為式(8) 4v v z 2 = 26. 35 m4f 22 2 () 21 + cr h + r ek (f ) =2c 2r 21 +頻譜整形濾波器對(duì)高頻信息補(bǔ)償以后, 相對(duì)無(wú)地層吸收衰減情況, 分辨率降低的百分?jǐn)?shù)為h(8)a rctg cr e 5 (f ) =1 + 2c 2r h (r e + r h )r 211r o 100 %= zo (-) 100 %= 23 %z oz 2頻譜整形濾波器對(duì)分辨率補(bǔ)償?shù)陌俜謹(jǐn)?shù)為 17 % 。也就是說(shuō)在損失 40 % 的分辨率中,

10、io syst em 中 的 ssf 只能補(bǔ)償 17 % , 還有 23 % 未被補(bǔ)償。其原 因是該 ssf 電路階次低 (相當(dāng)一階電路) , 則高頻提(下轉(zhuǎn)第 61 頁(yè))當(dāng)選擇 r h = 1 254 8、r h = 11 136 8、c = 0. 812 5 f時(shí), 頻譜整形系數(shù)的振幅譜和相位譜4210 + 39. 91 fk (f ) =104 + 0. 41 f 2(9)56. 85 r f5 (f ) = a rctg103 + 0. 40 r f 2頻率 (h z)4550556065707580地層吸收 (db )25. 027. 830. 533. 336. 138. 941.

11、 644. 4ssf 補(bǔ)償 (db )9. 210. 010. 711. 311. 812. 312. 813. 2頻率 (h z)510152025303540地層吸收 (db )2. 85. 68. 311. 113. 916. 719. 422. 2ssf 補(bǔ)償 (db )0. 41. 42. 74. 15. 36. 57. 58. 4ab s trac tschen , z. ch. : d evelop in g new gen era t ion geophy s ica l in strum en ts su ita ble f or the requ irem en ts of

12、petro leum exp lora t ion an d product ion of ch ina , p i, 1997, 11 (5) , 3 10.n ow aday s th e se ism ic p ro sp ect ing tech n ique s a re exp and ing in to th e exp lo ita t ion reg ion fo r th e w ho le w o r ld, th e re a re m anych a lleng ing tech n ica l p rob lem s faced w ith fo r se ism

13、ic tech no logy go ing in to exp lo ita t ion reg ion of ou r coun t ry . t h e m a in p rob lem s in c h ina, m o st o il2ga s accum u la t ing re se rvo ir a re sand re se rvo ir w ith con t inen ta l depo sit ion, th e th ick ne ss of sing le laye r is ve ry th in to be abou t seve ra l m e te r

14、s o r le ss. a cco rd ing to th e cap ab ility of p re sen t se ism ic re so lu t ion, on ly abou t 15 m e te r s th ick sand laye r s can be d ist ingu ish ed w ith 3 000m e te r s bu r ied deep. if w e p u sh th e se ism ic tech no logy to go deep ly in to exp lo ita t ion reg ion to do re se rvo

15、ir de scr ip t ion, ch a racte r iza t ion and su rve illance, th e se ism lc re so lu t ion h a s to be im p roved f ir st. t h e requ irem en t s of h igh 2re so lu t ion se ism ic tech no logy of c h ina a re m o re u rgen t th an any o th e r coun t ry. t h e p ract ica l need s of p e t ro luem

16、 exp lo ra t ion and p roduct ion of ou r coun t ry m u st be con side red in deve lop ing new gene ra t ion in st rum en t s. w e shou ld exe r t ou r se lve s in im pov ing th e dynam ic range of in stan taneou s reco rd ing, enh ancing h igh 2f requency info rm a t ion and be t te r signa l to no

17、 ise ra t io to m ee t h igh 2re so lu t ion exp lo ra t ion of ou r coun t ry f ina lly.subject w ords: se ism ic exp lo ra t ion, h igh re so lu t ion, in stan taneou s reco rd ing, dynam ic range, h igh f requency signa l2no ise ra t io , in te lligen t acqu isit ion sta t ionzen g, q. y. , l iu,

18、 y. , q i, y. w. an d zha o, sh. g. : a suma ry of telem etery se ism om eter s d evelopm en tl evel, p i, 1997, 11 (5) , 11 15.in o rde r to m ee t th e need s of h igh 2re so lu t ion se ism ic exp lo ra t ion, a ll k ind s of te lem e t ry se ism ic in st rum en t s a re deve lop edrap id ly and

19、v igo rou sly, acco rd ing ly w ide ly u sed in 3d se ism ic exp lo ra t ion. t h is a r t icle b r ief ly in t roduce s th e sup r io r ity of te lem e t ry se ism ic in st rum en t and th e nece ssity and cu r ren t leve l of it s deve lopm en t. b y m ak ing a com p a r ision w ith th e sp ecif i

20、ca t ion am ong som e typ e s of th e sy stem. t h e au tho r offe r s sugge st ion s on th e in st rum en t a lloca t ion fo r p ro sp e st ing crew.subject w ords: te lem e te r ing se ism om e te r, da ta t ran sm ission, h igh re so lu t ion, deve lopm en t leve l, sugge st ionhuan g, f. t. : je

21、n era l d evelopm en t s itua t ion in petro leum geo logy exper im en ta l techn iques, p i, 1997, 11(5) , 16 26.t h is p ap e r ou t line s th e p e t ro leum geo logy exp e r im en ta l tech n ique s of c h ina in recen t yea r s f rom 6 a sp ect s, such a s o rgan icgeoch em ist ry, p e t rop h

22、y sica l p rop e r ty, rock m ine ra l, rock g ra in , o il2ga s2w a te r and ino rgan ic ch em ist ry and eva lua te s a ll k ind s of th e exp e r im en ta l tech n ique s, th e ana ly t ica l m e thod s and th e app lica t ion s of th e exp e r im en ta l app a ra tu se s deve lop ed in a ll o il

23、 f ie ld s inc h ina and in t roduced f rom o th e r coun t r ie s. t h e p ap e r po in t s ou t th a t th e p e t ro leum geo logy exp e r im en ta l tech n ique s a re deve lop ing tow a rd s th e d irect ion of th e m icro, fa st2sp eed, m icroa rea, quan t ita t ive and m o lecu la r st ructu r

24、e ana ly sis, fu lly ref lect ing th a t th e p e t ro leum geo logy exp e r im en ta l tech ique s h ave m oved tow a rd s a new p h a se.subject w ords: p e t ro leum geo logy exp e r im en t, ana ly t ica l tech n ique, jene ra l deve lopm en t situa t ion , com p reh en sive eva lua t ionguan ,

25、w. l. , w an , z. m. an d chen , y. ch. : 3d phy s ica l-m odel in g exper im en ta l equ ipm en ts an dexper im en ta l techn iques, p i, 1997, 11 (5) , 27 30.a se t of exp e r im en ta l equ ipm en t s of low 2p re ssu re sca le m ode l and th e co r re spond ing labo ra to ry exp e r im en ta l t

26、ech n ique s h avebeen deve lop ed succe ssfu lly by e xp lo ra t ion and d eve lopm en t r e sea rch in st itu te of l iaoh e o ilf ie ld. t h e exp e r im en ta l equ ipm en t s and tech n ique s h ave been w ide ly u sed in scien t if ic re sea rch and p roduct ion. t h e p ap e r in t roduce s t

27、h e exp e r im en ta l equ ipm en t s, expound s th e th ree2dem en t iona l p h y sica l m ode ling exp e r im en ta l tech n ique and it s deve lopm en t t rend in fu tu re.subject w ords: o il re se rvo ir num e r ica l sim u la t ion, th ree2dem en t iona l m ode l, exp e r im en ta l equ ipm en

28、 t, low 2p re ssu re sca le m ode l, deve lop ing t rendha o, z. x. , zhuan g,m. zh. an d sun , z. ch: w el l-test an d test in g techn o logy fa c il it ies in ch ina , p i, 1997, 11(5) , 31 33, 53.t h e fo rm a t ion eva lua t ion te ste r is a advanced w e ll2te st equ ipm en t, w h ich began to

29、be im po r ted and deve lop ed in th e 1970sin c h ina. a ll k ind s of fo rm a t ion te ste r s im po r ted f rom aboa rd and deve lop ed by it se lf a re in t reduced sy stem a t ica lly, a s w e ll it s st ructu re fea tu re s, funct ion s and u se a re in t roduced in cla ssif ica t ion.subject

30、w ords: exp lo ra t ion and w e ll2te st, te st ing tech no logy equ ipm en t, st ructu ra l fea tu rey uan , z. l. an d ya o, j. ch. : com puter ana logue study on spectrum sha p in g techn o logy, p i, 1997, 11 ( 5) , 34 36, 61.t h e effect of ea r th s ab so rp t ion w ane to th e h igh f requenc

31、y signa l is th e ch ief rea son fo r cau sing th e re so lu t ion of th e se ism icp ro sp ect ing no t be ing h igh. in th e f ie ld se ism ic da ta sy stem of h igh re so lu t ion, th e sp ect rum sh ap ing f ilte r (ssf ) is a im po r tan t p a r t w h ich w e se t. in th is p ap e r, th e re la

32、 t ion s be tw een th e ea r th s ab so rp t ion w ane and th e comm un ica t ion d istance of se ism ic w ave, f requence, t im e and m ed ium ve locity a re d iscu ssed. t h e leve l of re so lu t ion reducing due to ea r th s ab so rp t ion w ane andth e ssf com p en sa t ion effect to th e h igh

33、 f requency signa l a re stud ied by u sing th e com p u te r ana logue tech n ique. it is po in ted ou t th a t th e ssf re so lu t ion com p en sa t ion is on ly abou t 42. 5% in th e re so lu t ion reducing cau sed by ea r th s ab so rp t ion w ane.subject w ords: se ism ic exp lo ra t ion, ea r

34、th s ab so rp t ion, h igh re so lu t ion, f requency sp ect rum , sh ap e f ilte r ingsha o, r. x. : the se ism ogra ph in terf eren ce s igna l s an d restra in t m ethods, p i, 1997, 11 (5) , 37 40.a t p re sen t, th e se ism og rap h w ith 242b it a d conve r te r h a s low no ise, low d isto r

35、t ion, h igh sam p le ra te and la rge rin stan taneou s dynam ic range. it h a s rea lized th e reco rd of m icro 2vo lt signa ls, crea ted th e cond it ion fo r th e se ism ic p ro sp ect ing of th e h igh re so lu t ion. a lthough th e geop hone p ick ing up se ism ic signa ls doe s no t reach th

36、 e deve lopm en t leve l of p re sen tse ism og rap h, a lso ach ieve s a cen ta in of th e p rog re ss. n ow th e m e thod s and m ean s re st ra ined th e env irom en ta l in te rfe rence signa l a lm o st h ave no p rog re ss du r ing th e se ism ic acqu isit ion. th u s th e se in te rfe rence s

37、igna ls m e rge th e w eak h igh 2f requeney ref lect ion signa ls in se ism ic p ro sp ect ing. becau se th e se in te rfe rence signa ls h ave w ide f requeney2baud and random , w e seem h av ing no w ay ou t it. in fact, w e can effect ive ly re st ra in th em by ana lyzing th e p a th en te red

38、by th e in te rfe rence singna ls, m ak e th e inf luence of th e in te rfe rence signa ls on effect ive se ism ic signa ls ruduce to a m in ium in o rde r to enh ance th e signa l2no ise ra te of se ism ic da ta. subject w ords: se ism om e te r, in te rfe rence signa l, comm on inh ib it ion , cab

39、 le, se ism og rap hhe, d. q. : the new techn ique of l a ser m icro sam p l in g f or iso top ic ana ly s is, p i, 1997, 11 (5) , 41 44, 49.w ith th e m icro 2ana ly sis ga s m a ss sp ect rom e te r suppo r ted, th e new tech n ique of la se r m icro sam p ling fo r iso top ic ana ly sis isu sed t

40、o ana lyze and m ea su re th e iso top e va lue s by u sing h igh 2pow e r facu sed la se r fo r h ea t ing and ab la t ing m ine ra l sam p le. it h a s abou t th e sam e ana ly sis p recision a s conven t iona l m e thod (e. g. ca rbona te m ine ra l: 13c , = 0. 1% ; 18o , = 0. 2% ) , and w ithh i

41、gh sp ace re so lu t ion. b y th is m e thod, w e can ge t iso top e va lue s of a ll k ind s of f ine st ructu re com po sit ion in m ine ra l sam p le, and deve lop th e study of iso top e geo logy and o il2ga s re se rvo ir geo logy.subject w ords: ana lyze r, geoch em ist ry , la se r m icro sam

42、 p le, iso top e ana ly sis, ca rbona te rockw en g, y. sh. : d evelopm en t an d u t il iza t ion of the v ir tua l in strum en t techn o logy, p i, 1997, 11 (5) , 45 46.t h is p ap e r sim p ly de scr ibe s th e v ir tua l in st rum en t sy stem w h ich is a da ta acqu isit ion and con t ro l sof

43、tw a re p ack age fo rm icro sof t w indow s o r d o s. t h e v ir tua l in st rum en t sy stem deve lop ed on gene ra l io dev ice s and u se rs dll pog ramm ed w ithm icro sof t v isua l c language a re in t roduced.subject w ords: com p u te r, v ir tua l in st rum en t, dll ,m icro sof t w indow

44、 sw an g, d. l. an d m a , r. l. : d evelopm en t of a utoma t ic po s iton in g d etector f or hor izon ta l w el l pref ora t ion ,p i, 1997, 11 (5) , 47 49.w ith th e deve lopm en t of new tech n ique s of ho r izon ta l w e ll d r illing, a new re sea rch p rob lem h a s a r isen fo r logg ingp

45、e rfo ra t ion, th a t is , how to adop t de rect iona l p refo ra t ion tech no logy to accu ra t ly shoo t dow n to o il re se rvo ir. com b ined w ith th e need s of p e t ro leum p roduct ion, l ogg ing e ng inee r ing d ep a r tm en t of c h angq ing p e t ro leum e xp lo ra t ion b u reau h a

46、s deve lop ed a se t of ho r izon ta l2w e ll p e rfo ra t ion equ ipm en t s, com po sed of au topo sit ion p e rfo ra t ing gu s, de tecto r and signa ls sen so r. t h e au tom a t ic po siton ing de tecto r is im po r tan t com ponen t of th e de rect iona l2w e ll p refo ra t ion tech no logy, u

47、 sed to de tect th e p rofo ra t ion azim u th and im p rove it s accu racy. t h e new tech no logy h a s been u sed in c h angq ing sp 2 w e ll, succeed in one st rok e. t h e sp ecif ica t ion s a ll com e up to th e de sign requ r im en t s.subject w ords: p e rfo ra to r, ho r izon ta l w e ll,

48、au tom a t ic po sit ion ing, de tecto rzhen g, j. x. an d chen , y. q. : v ibra con s isten cy an d a pp l ica t ion of v ibra check, p i, 1997, 11 (5) , 50 53.s tanda rd izing v ib ra day2ch eck con sistency is of g rea t im po r tance to qua lity m on ito r ing and accep tance in v ib ro shockp roduct ion. p roceed f rom th e actua l dem and s, th e p ap e r expound s th e nece ssity and sup e r io r ity of v ib ra to r con sistency done by m ean s of v ib ra ch eck. t h e m a thm a t ic p r incip le of ch eck ing v ib ra to r by v ib ra ch eck