可控源音頻大地電磁測(cè)深法應(yīng)用實(shí)例_圖文

1、第28卷第4期物探化探計(jì)算技術(shù)2006年11月 收稿日期:2005-04-29文章編號(hào):10011749(200604033705可控源音頻大地電磁測(cè)深法應(yīng)用實(shí)例黃力軍,陸桂福,劉瑞德(中國(guó)地質(zhì)科學(xué)院地球物理地球化學(xué)勘查研究所,廊坊065000摘要:目前對(duì)電法的探測(cè)深度要求越來(lái)越高,常規(guī)電法有時(shí)難以滿足實(shí)際工作需要。與常規(guī)電法相比,可控源音頻大地電磁測(cè)深法具有探測(cè)深度大、設(shè)備相對(duì)輕便和橫向分辨率高等特點(diǎn),已廣泛應(yīng)用于地?zé)豳Y源、水文地質(zhì)、有色金屬礦產(chǎn)和工程地質(zhì)勘查工作之中,并取得了令人十分滿意的實(shí)際應(yīng)用效果。這里介紹的是一些具有代表性可控源音頻大地電磁測(cè)深應(yīng)用實(shí)例和應(yīng)用成果,這些實(shí)例基本函概了目

2、前電法的主要應(yīng)用范疇,常規(guī)電法難以勝任的地質(zhì)調(diào)查工作。實(shí)例中包括斷陷盆地型地?zé)豳Y源和深部基巖裂隙水調(diào)查,危機(jī)礦山深部找礦和復(fù)雜地形條件下鐵路隧道工程勘查。關(guān)鍵詞:電磁測(cè)深;地?zé)豳Y源;水文地質(zhì);有色金屬礦產(chǎn);工程地質(zhì);調(diào)查中圖分類號(hào):P 63113+25文獻(xiàn)標(biāo)識(shí)碼:A0前言可控源音頻大地電磁測(cè)深是在音頻大地電磁測(cè)深(AMT 基礎(chǔ)上,發(fā)展起來(lái)的一種人工源頻率測(cè)深方法。上世紀(jì)五十年代,在卡尼亞(L Cagn 2iard 論文1的基礎(chǔ)上,發(fā)展形成了基于觀測(cè)天然場(chǎng)大地電場(chǎng)和磁場(chǎng)正交分量,計(jì)算視電阻率的大地電磁測(cè)深方法。在音頻(n ×10-1Hz n ×103Hz 范圍內(nèi),大地電磁場(chǎng)相

3、對(duì)較弱,人文干擾較大。為了克服上述困難,七十年代初,D W Strang way 教授和他的學(xué)生M A Goldstein 2,3提出沿用AMT 的測(cè)量方式,觀測(cè)人工供電產(chǎn)生的音頻電磁場(chǎng)。由于所觀測(cè)的電磁場(chǎng)頻率、場(chǎng)強(qiáng)和方向均由人工控制,其觀測(cè)的方式與AMT 相同,所以稱其為可控源音頻大地電磁測(cè)深(簡(jiǎn)稱CS AMT 法。CS AMT 法可以采用磁性源或電性源二種人工場(chǎng)源,目前主要應(yīng)用電性源可控源音頻大地電磁測(cè)深法?？煽卦匆纛l大地電磁測(cè)深是以有限長(zhǎng)接地導(dǎo)線為場(chǎng)源,在距場(chǎng)源中心一定距離處同時(shí)觀測(cè)電、磁場(chǎng)參數(shù)的一種電磁測(cè)深方法。目前應(yīng)用大多采用赤道偶極裝置進(jìn)行標(biāo)量測(cè)量,同時(shí)觀測(cè)與場(chǎng)源平行的電場(chǎng)水平分量

4、E x 和與場(chǎng)源正交的磁場(chǎng)水平分量H y (測(cè)量裝置布置見(jiàn)圖1。利用電場(chǎng)振幅E x和磁場(chǎng)振幅H y 計(jì)算卡尼亞阻抗電阻率s ,電場(chǎng)相位E p 和磁場(chǎng)H p 計(jì)算卡尼亞阻抗相位s 。阻抗電阻率和阻抗相位聯(lián)合反演計(jì)算反演電阻率參數(shù),利用反演電阻率進(jìn)行地質(zhì)推斷解釋。目前,可控源音頻大地電磁測(cè)深反演主要采用一維電阻率圓滑反演方法4。圖1標(biāo)量CS AMT 測(cè)量裝置示意圖Fig .1Scalar CS AM T survey array十幾年來(lái),我們一直從事可控源音頻大地電磁測(cè)深應(yīng)用研究和生產(chǎn)工作,在各個(gè)應(yīng)用領(lǐng)域中均做過(guò)很多工作。在本文中,作者以典型實(shí)例介紹了可控源音頻大地電磁測(cè)深方法的實(shí)際應(yīng)用及應(yīng)用效果

5、。1地?zé)豳Y源調(diào)查作為綠色能源,地?zé)豳Y源的開(kāi)發(fā)利用日益受到人們的廣泛重視。一般情況下,地?zé)豳Y源埋藏較深,開(kāi)采風(fēng)險(xiǎn)很大。為了提高效率,降低成本,減少投資風(fēng)險(xiǎn),在開(kāi)發(fā)地?zé)豳Y源前,大多進(jìn)行地質(zhì)調(diào)查,地球物理勘查就是地?zé)豳Y源調(diào)查的重要手段之一。地下熱水能夠使熱儲(chǔ)層位電阻率降低,低阻異常是識(shí)別地?zé)豳Y源的重要標(biāo)志,所以在以往地?zé)豳Y源調(diào)查中,直流電阻率法一直占主導(dǎo)地位。但直流電阻率法的工作效率低,勘探深度相對(duì)較淺,在使用中受較大限制。目前地?zé)豳Y源開(kāi)發(fā)的深度越來(lái)越大,大多開(kāi)采深度已超過(guò)2000m。隨著深度加大,地表觀測(cè)到的由地下熱水引起的電阻率差異越來(lái)越小,以至難以觀測(cè)到由地?zé)嶙兓鸬碾娮杪十惓?所以,深部地

6、熱資源調(diào)查的主要任務(wù)是勘查熱儲(chǔ)地層及地質(zhì)構(gòu)造分布情況。近幾年,我們采用可控源音頻大地電磁測(cè)深法,分別在北京、遼寧、河北、江西、江蘇和浙江等地的深部地?zé)豳Y源調(diào)查中,均取得了較好的地質(zhì)效果。斷陷盆地型熱水埋深相對(duì)較大,以中低溫為主,分布范圍較廣,是目前利用最廣的地?zé)豳Y源,在北京已經(jīng)得到廣泛地開(kāi)發(fā)和利用。北京市及周邊地區(qū)薊縣系霧迷山組白云巖厚度較大,埋深一般0mn×1000m,巖溶裂隙較為發(fā)育,熱導(dǎo)率值較高,是北京市主要熱儲(chǔ)地層。該區(qū)地?zé)峥辈橹饕蝿?wù)是了解薊縣系白云巖埋藏深度、上覆地層和構(gòu)造分布情況。以北京市遠(yuǎn)郊某區(qū)為勘查實(shí)例,該測(cè)區(qū)大部為第四系所覆蓋,第四系(Q由粘土、粉砂和砂礫石組成;

7、第四系下部為白堊系(K砂巖和侏羅系(J砂巖,侏羅系內(nèi)穿插有火山巖;侏羅系下部為薊縣系(Jx,巖性主要為白云巖。在測(cè)區(qū)內(nèi)地層間電性差異較為明顯,第四系電阻率較低,約20m左右;白堊系電阻率20m 50m;侏羅系砂巖電阻率為50m 100m;薊縣系白云巖電阻率大于500m。各時(shí)代地層巖性之間電阻率存在明顯差異,為開(kāi)展電法勘探工作提供了充分的地球物理前提。圖2是該測(cè)區(qū)某地可控源音頻大地電磁測(cè)深反演電阻率和地質(zhì)解釋綜合斷面圖。由圖2可見(jiàn),斷面內(nèi)除x=1500m附近出現(xiàn)斷裂破碎帶外,從剖面起點(diǎn)到端點(diǎn)斷面電阻率逐漸升高,符合實(shí)際地層呈單斜變化趨勢(shì)。斷面內(nèi)0m-500m為第四系,河灘局部出現(xiàn)高阻外,電阻率均

8、很低;除第四系和白堊系間電阻率差異較小,層間電阻率呈漸變關(guān)系,除兩者間界面不太明顯外,白堊系侏羅系薊縣系界面非常清楚。實(shí)際驗(yàn)證(地?zé)峋Y(jié)果, 1296m見(jiàn)薊縣系白云巖,利用CS AMT反演電阻率推斷薊縣系白云巖頂界面深度與實(shí)際地?zé)峋?yàn)證深度結(jié)果僅差幾十米(見(jiàn)圖2。該地?zé)峋验_(kāi)發(fā)出溫度71°C,出水量2000m3/d以上的地下熱水。由于地?zé)衢_(kāi)發(fā)井終孔于斷裂破碎內(nèi),是北京市目前溫度和出水量最高的地?zé)衢_(kāi)發(fā)井 。圖2北京市某地CS AM T地?zé)峥辈榫C合斷面圖Fig.2The comp rehensive cr oss secti on ofCS AM T exp l orati on,Bei

9、jing2水文地質(zhì)調(diào)查直流電阻率測(cè)深法是淺部基巖裂隙水調(diào)查的主要手段。但其勘探深度相對(duì)較小,施工過(guò)程相對(duì)較為繁瑣。當(dāng)?shù)乇碚系K物較多時(shí),施工非常困難,尤其隨著深度加大,直流電阻率測(cè)深法更加難以滿足實(shí)際工作需要。下面是北京郊區(qū)水文地質(zhì)調(diào)查實(shí)例。目前,北京應(yīng)用的地下水主要分二個(gè)方面:一個(gè)是灰?guī)r或白云巖巖溶裂隙水;另一個(gè)是斷裂構(gòu)造水。由于奧陶系灰?guī)r巖溶破碎相對(duì)發(fā)育,與其它相應(yīng)巖層相比埋深較淺,因而是目前北京市地下水開(kāi)發(fā)的主要來(lái)源?？碧絽^(qū)為第四系覆蓋,附近地表出露有石炭二迭系(C-P、奧陶系(O和寒武系(。其中,石炭二迭系主要為砂巖、頁(yè)巖和泥巖,電阻率100m左右;奧陶系主要為灰?guī)r,電阻率大于500m;

10、寒武系主要為砂巖、頁(yè)巖和灰?guī)r,電阻率100m300m。剖面附近出露有花崗巖體。833物探化探計(jì)算技術(shù)28卷可控源音頻大地電磁測(cè)深的勘查目的是,利用剖面測(cè)量方法確定實(shí)測(cè)剖面內(nèi)地層、花崗巖體和地質(zhì)構(gòu)造的分布情況,勘探深度2000m 。圖3是區(qū)內(nèi)實(shí)測(cè)剖面CS AMT 勘查綜合斷面圖。由圖3可見(jiàn),除表層外,反演電阻率曲線可大致分為四個(gè)值區(qū),其中從剖面起點(diǎn)到x =1300m 處為高值區(qū),平均電阻率大于1000m ,推斷為花崗巖體產(chǎn)生;從x =1300m 處到剖面末端的區(qū)域內(nèi),由上至下又分為三個(gè)值區(qū),反演電阻率曲線為K 型,根據(jù)反演電阻率曲線及對(duì)應(yīng)巖石電性,推斷由上至下分別為石炭二迭系、奧陶系和寒武系(地

11、質(zhì)推斷結(jié)果見(jiàn)圖3 。圖3北京市某鄉(xiāng)CS AM T 水文地質(zhì)勘查綜合斷面圖Fig .3The comp rehensive cr oss secti on of CS AMThydr ogeol ogical exp l orati on,Beijing圖3內(nèi)水文井為地下水開(kāi)發(fā)鉆孔,鉆孔揭露上部見(jiàn)有砂頁(yè)巖,下部為花崗巖和蝕變灰?guī)r,地層深度與解釋結(jié)果基本一致,終孔于斷裂破碎帶中(井深1000m ,出水量1000m 3/d 以上。3危機(jī)礦山深部找礦電法在金屬礦產(chǎn)物探勘查工作中一直占有重要地位,隨著找礦工作的進(jìn)一步深入,淺表礦日益減少,尋找深部隱伏礦是今后找礦的主要目標(biāo)。另一方面,找礦工作重點(diǎn)已經(jīng)逐漸

12、轉(zhuǎn)向我國(guó)西部地區(qū),西部地區(qū)地表和地形條件更加復(fù)雜,一些常規(guī)電磁法已無(wú)法滿足深部及復(fù)雜地形條件工作需要。可控源音頻大地電磁測(cè)深方法采用定源觀測(cè),具有輕便、快速和勘探深度大等優(yōu)點(diǎn),其在復(fù)雜地形條件和深部找礦工作中,確定成礦有利地段和隱伏礦定位預(yù)測(cè)等方面起到了其它方法無(wú)法替代的重要作用。這里的定位預(yù)測(cè)實(shí)際上是指在詳查找礦階段,采用以電測(cè)深為主的方法手段對(duì)礦(化體進(jìn)行二維或三維空間定位。根據(jù)其產(chǎn)狀、規(guī)模和延伸(深情況,結(jié)合已知地質(zhì)和其它資料進(jìn)行合理地質(zhì)解釋的一種找礦方法技術(shù)。在實(shí)際工作中,我們一般采用中梯裝置的時(shí)間域激發(fā)極化方法,尋找勘查區(qū)內(nèi)成礦有利地段,使用可控源音頻大地電磁測(cè)深法,在成礦有利地段對(duì)

13、礦(化體進(jìn)行定位預(yù)測(cè),并結(jié)合地質(zhì)、地球化學(xué)和其它資料進(jìn)行綜合研究的找礦方法。事實(shí)表明,上述方法在實(shí)際找礦工作中可取得明顯的地質(zhì)效果。下面是甘肅白銀有色金屬公司小鐵山礦深部找礦實(shí)例。白銀有色金屬公司是五十年代初興建的我國(guó)最大的銅有色金屬生產(chǎn)基地,近十年來(lái),后備礦源出現(xiàn)危機(jī)。1992年我所參加白銀礦區(qū)地質(zhì)和物化探綜合找礦研究工作,經(jīng)過(guò)充分研究前人在中、大比例尺地質(zhì)和物化探資料基礎(chǔ)上,在小鐵山礦區(qū)選擇成礦有利地段進(jìn)行100m ×20m 網(wǎng)度的可控源音頻大地電磁面積性測(cè)量及重點(diǎn)剖面的巖石地球化學(xué)、重力測(cè)量工作。小鐵山礦床是一個(gè)隱伏的海相火山巖Pb 、Zn 、Cu 多金屬礦床。地表僅有一鐵帽露

14、頭,礦體全部埋藏于深部。區(qū)內(nèi)出露的地層為白銀群變質(zhì)火山巖,可分為上、中、下三層,即上部石英角斑巖夾角斑凝灰?guī)r;中部為硅質(zhì)千枚巖夾石英角斑凝灰?guī)r層;下部為石英角斑凝灰?guī)r層。小鐵山含礦帶富存于一背斜軸部的石英角斑凝灰質(zhì)碎裂巖中,礦化帶上盤為硅質(zhì)千枚巖,下盤為石英鈉長(zhǎng)斑巖體,已知礦的性質(zhì)和分布與斷裂構(gòu)造關(guān)系密切。資料處理后分別在相距100m 的12線和13線可控源音頻大地電磁測(cè)深反演電阻率斷面內(nèi),出現(xiàn)相互對(duì)應(yīng)的二處低阻異常(1和2異常,其中1(1-1和1-2異常異常對(duì)應(yīng)已知礦體,2異常位于深部探礦工程的空白地段的175號(hào)點(diǎn)附近,12線的2異常位于海拔1100m 1800m 處,為單一低阻異常;13線

15、的2異常由二部分組成(21和22異常,其中21異常位于海拔1400m 1700m 處,22異常位于21異常下方海拔850m 1400m 處(見(jiàn)下頁(yè)圖4。根據(jù)地質(zhì)資料和綜合物化探異常,白銀有色金屬公司地質(zhì)隊(duì)1994年采用鉆探驗(yàn)證(鉆孔編號(hào)bzk112線的2異常。鉆孔揭露484135m 終孔(724102m 之間均處于蝕變礦化巖石和近礦圍巖內(nèi),其中銅礦化有向下增高趨勢(shì)(Cu 平均含量0104%,最高含量達(dá)01095%,高于礦體近礦圍巖含量(01036%和本區(qū)背景值(010022%。由于工程故障,鉆孔未到設(shè)計(jì)深度(800m 。9334期黃力軍等:可控源音頻大地電磁測(cè)深法應(yīng)用實(shí)例圖4小鐵山礦區(qū)13線C

16、S AM T反演電阻率異常和鉆孔驗(yàn)證結(jié)果Fig.4CS AM T exp l orati on comp rehensive crs oss secti on,Xiaotieshan M ine在距12線100m處的13線布置22異常驗(yàn)證孔(鉆孔編號(hào)13B2,見(jiàn)厚1717m,綜合品位(Cu、Pb和Zn達(dá)17%的工業(yè)礦體;由于礦體埋深較大,后來(lái)加拿大明科公司在1547m的巷道內(nèi)連續(xù)施工三個(gè)定向孔,每個(gè)鉆孔均見(jiàn)工業(yè)礦體5,礦體的總金屬量為450000t。這是目前我國(guó)礦山深部物化探找礦成功的實(shí)例。在小鐵山深部找礦工作中CS AMT方法起到了關(guān)鍵的,其它方法難以做到的定位預(yù)測(cè)作用。4工程地質(zhì)勘查地震勘

17、探一直是工程地質(zhì)勘查的主要手段,在地震勘探難以施工地區(qū),多采用直流電阻率測(cè)深或瞬變電磁測(cè)深方法等常規(guī)電法。在通常情況下,常規(guī)電法勘探深度較小,同時(shí)受到地表?xiàng)l件影響,在復(fù)雜地形條件下,直流電阻率測(cè)深和瞬變電磁測(cè)深方法等常規(guī)電法很難完成相應(yīng)的勘查工作。以CS AMT法鐵路隧道勘查工作為實(shí)例。寺鋪尖隧道位于太行山深處,是朔黃鐵路上最長(zhǎng)的一個(gè)隧道。隧道全長(zhǎng)6400m,隧道通過(guò)的地段地表?xiàng)l件非常復(fù)雜,相對(duì)高差超過(guò)1000m,大多地段行人難以通行?？辈槟康氖翘綔y(cè)隧道通過(guò)的地段地層、可能富水地段和地質(zhì)構(gòu)造分布等情況,探測(cè)深度為1000m。在實(shí)際工作中,我們采用隧道上部和隧道二側(cè)相互結(jié)合的測(cè)量方法。即盡量在設(shè)

18、計(jì)隧道上部測(cè)量,當(dāng)設(shè)計(jì)隧道上部難以通過(guò)時(shí),采用在隧道二側(cè)布設(shè)測(cè)線,用二側(cè)剖面測(cè)量結(jié)果來(lái)推斷隧道通過(guò)地段地質(zhì)情況的勘查方法。寺鋪尖隧道區(qū)除溝谷中分布有第四系洪積層外,大部基巖裸露;隧道出口段出露有太古界五臺(tái)山群混合花崗巖;隧道進(jìn)口段主要出露有古生界中、上寒武系(2+3灰?guī)r,其中,中寒武系下部為頁(yè)巖;山頂處出露奧陶系下統(tǒng)(O1灰?guī)r。出口處半坡見(jiàn)有下寒武系(1黃紫色頁(yè)巖直接角度不正合于太古界地層之上。統(tǒng)計(jì)結(jié)果表明:奧陶系下統(tǒng)電阻率800m1200m;寒武系中、上統(tǒng)電阻率500m800m;寒武系下、中統(tǒng)電阻率500m800m;太古界五臺(tái)山群電阻率大于1500m。圖5(a(見(jiàn)下頁(yè)是其中一條旁測(cè)剖面的CS

19、 AMT反演電阻率斷面圖。我們根據(jù)CS AMT反演電阻率橫向變化(電阻率橫向間斷推斷出剖面通過(guò)地段斷層展布情況,這里推斷出五條斷層(分別將其編號(hào)為F2、F3、F4、F3+1和F5斷層;結(jié)合巖石物性及電阻率隨著深度變化推斷出地層分布情況。圖5(b是根據(jù)二條旁測(cè)剖面測(cè)量結(jié)果推斷的設(shè)計(jì)隧道地質(zhì)推斷解釋斷面圖(局部。施工單位利用我們預(yù)測(cè)結(jié)果施工,實(shí)際結(jié)果證明我們推斷的地層地質(zhì)構(gòu)造均較準(zhǔn)確6。這是目前CS AMT法在復(fù)雜地形條件下工程地質(zhì)勘查工作中比較成功的應(yīng)用實(shí)例。043物探化探計(jì)算技術(shù)28卷圖5朔黃鐵路寺鋪尖隧道CS AMT勘查綜合斷面圖Fig.5CS AMT exp l orati on comp

20、 rehensive crs oss secti on,Si pujian Tunnel5結(jié)語(yǔ)作為一種人工源電磁法,在可控源音頻大地電磁測(cè)深方法測(cè)量中不可避免地會(huì)存在場(chǎng)源效應(yīng)。所以在實(shí)際工作中,應(yīng)根據(jù)工作任務(wù),結(jié)合實(shí)際地質(zhì)和地層電性分布情況,合理地選擇場(chǎng)源方向、收發(fā)距和采樣頻率范圍。在保證最佳信噪比情況下,要盡量使所采集的數(shù)據(jù)處在遠(yuǎn)區(qū)。在數(shù)據(jù)處理中,要注意識(shí)別場(chǎng)源效應(yīng)和靜態(tài)效應(yīng)等影響引起的數(shù)據(jù)畸變,慎重處理這些效應(yīng)的影響。無(wú)論資源開(kāi)發(fā)還是工程施工進(jìn)行前期調(diào)查均可以提高效率、降低成本、減少風(fēng)險(xiǎn)。實(shí)際應(yīng)用結(jié)果表明,可控源音頻大地電磁測(cè)深法能夠適應(yīng)復(fù)雜地形條件,滿足探測(cè)深度較大的地質(zhì)勘查工作要求。需

21、要說(shuō)明的是,隨著勘探深度加大,其勘查手段必須提高觀測(cè)和解釋精度,以加大勘探深度,提高方法的實(shí)際應(yīng)用效果。另一方面,引起地下電阻率變化的因素很多,利用可控源音頻大地電磁測(cè)探法勘查,需要結(jié)合已知地質(zhì)、地球物理特征和其它有關(guān)資料進(jìn)行綜合研究,合理地進(jìn)行地質(zhì)解釋。上述實(shí)例表明,在一些地?zé)豳Y源、水文地質(zhì)、有色金屬礦產(chǎn)資源和工程地質(zhì)等地質(zhì)勘查工作中,可控源音頻大地電磁測(cè)深法能夠起到其它方法無(wú)法起到的作用。參考文獻(xiàn):1C AG N I A RD L.Basic theory of the magnet otelluric meth2od of geophysical p r os pectingJ.Geop

22、hysics,1953,18:605.2STRANG WAY D W,S W I FT C M,HOLMER R C.Theapp licati on of audi o2frequency magnet otellurics(AM Tt o m ineral exp l orati onJ.Geophysics,1973,38:1159.3G OLDSTE I N M A,STRANG WAY D W.Audi o2frequen2cy magnet otellurics with a grangded electric di poles ourceJ.Geophysics,1975,40:

23、1159.4C ONST ABLE S C,P ARKER R L,C ONST ABLE C G.Occa ms inversi on:A p ractical algorith m for generatings mooth models fr om electr omagnetic s ounding dataJ.Geophysics,1987,52(3:289.5胡達(dá)驤,徐葉兵,陳群,譯.明科礦業(yè)及金屬公司在白銀廠地區(qū)找礦新進(jìn)展J.地質(zhì)與勘探,1999,35(2:1.6杜彥軍,王皓,李瑋.可控源音頻大地電磁測(cè)深法在寺鋪尖隧道勘察中的應(yīng)用J.鐵路地質(zhì)與地基,1998,37(1:19.作者

24、簡(jiǎn)介:黃力軍(1954-,男,1982年畢業(yè)于長(zhǎng)春地質(zhì)學(xué)院物探系,1992年獲中國(guó)地質(zhì)大學(xué)(北京碩士學(xué)位,教授級(jí)高級(jí)工程師,主要從事電磁法勘查研究和生產(chǎn)工作。1434期黃力軍等:可控源音頻大地電磁測(cè)深法應(yīng)用實(shí)例 Nov. 2006 COMPUTI G TECHN I UES FOR GEOPHYSICAL AND GEOCHEM ICAL EXPLORATI N N Q O 3 WANG Zhi2gang , HE Zhan 2xiang , W E I W en 2 3 ( 1. China University of Geosciences, Beijing bo 100083, Chin

25、a; 2. Departm ent of East Geophysical Company, Zhuozhou Heibei Province 072751, Chi2 na; 3. Geo - detection laboratory,M inistry of Educa2 tion, B eijing 100083, China . COM PU T IN G TECH 2 1, 2, 3 2 study the results of p rocession. Key words: high density resistivity m ethod; defect error; accide

26、ntal error; p rep rocess APPL ICAT I N O F PO TENT IAL F IELD NO R2 O M AL IZED DOW NW ARD EXTRAPOLAT I N IN O SP PRO BAB I ITY TOMO GRAPHY L RUAN Shuai, WANG Xu 2ben, GAO Yong2cai, et al . ( College of Information Engineering, University of Science and Technology of Chengdu, Chengdu Si2 chuan 61005

27、9, China . COM PU T IN G TECHN IQU ES RA T ION , 2006, 28 ( 4 : 332 N IQU ES FOR GEO PHYS ICAL AND GEOCHEM ICAL EX PLORA T ION , 2006, 28 ( 4 : 322 THE AR ITHM ET IC O F THE DATA PREPRO 2 CESS ING IN THE H IGH D ENS ITY RES IS IT IV2 ITY M ETHOD L I Yi2nian, LUO Yan 2zhong ( Institute of Geophysics

28、and Geom atics, China University of Geosciences, W uhan 430074, China . COM PU T IN G TECH 2 N IQU ES FOR GEO PHYS ICAL AND GEOCHEM ICAL EX PLORA T ION , 2006, 28 ( 4 : 328 The high density resisitivity m ethod through elec2 trode power supp ly, surveys electric current and volt2 age, gathers appare

29、nt resistivity data. B ecause of fault in operation and the p recision of instrum ent, the defect error and accidental error are involved in the p rocession of data collection, the defect error that are brought by m istakes of peop le and influence of outside is large, the contingency error that are

30、 inevitably and random icity is little. The m ission of computer is to lim it the defect error, supp ress the accidental error and m ini izes the influence of these errors to the in2 m version result This Paper analyzes the reason of error . s appearance and the characters of the m ethod of re2 sist

31、ivity p rocessing, compares the manual work w ith computer calculate p rogram , gives out several data perp rocessing p rogram s which base on different arith2 metics for the p rocession of error - lim itation, and The paper discusses the calculation method of field induced by vertical line sources

32、by segments and field stacking The method realizes 3D modeling of . field induced by DC in cased well The paper analy2 . zes comp ress storage of large coefficient m atrix which realizes 1D chain comp ress storage of coefficient ma2 trix by combination of array and structure. During so2 lution of su

33、pper - large sparse system of linear equa2 tions, incomp lete Cholesky factorization of stabilized biconjugate gradient ( I CBG method is app lied. Comparing of the analytic solutions and numerical ones of line sources in homogeneous half - space indi2 cates that the m ethod is accurate and reliable

34、. Key words: DC borehole 2ground m ethod; comp ress storage; 3D finite difference method; biconjugate gra2 dient m ethod; incomp lete cholesky factorization CO NTROLL ED SO URE AUD I - FREQUENCY O M AGNETO TELL UR ICS HUANG L i2jun, LU Gui2fu, L I Rui2de ( Institute of U Geophysical and Geochem ical

35、 Exp loration, CAGS Langfang 065000, China . COM PU T IN G TECH 2 N IQU ES FOR GEO PHYS ICAL AND GEOCHEM ICAL EX PLORA T ION , 2006, 28 ( 4 : 337 B ased on the normalized downward extrapolation theory, we have i p roved vertical p recision of tradi2 m tional surface self - potential ( SP tomography

36、meth2 od, of which p rocessing only uses the surface ob2 served voltages After that, external lim itations that . cause the shortages in rep resenting the whole under2 ground information can be volum inously avoided. During model analysis, the new tomography schem e can p rovide more exact results t

37、o fit the true original model. Towards the p ractical data exp lanations, it ac2 curately gives both horizontal abnor ity corresponding m w ith p ractical survey and vertical infor ation of whole m underground space. Key words: Self - potential, Surface SP Tomo2 graphy, Normalized Downward Extrapola

38、tion W ith the dep th increasing of the underground ob2 jects to be p rospected, the conventional electric meth2 ods are difficult to m eet the p rospecting requirem ents . Compared w ith the conventional electric m ethods, the Controlled source audio - frequency magnetotellurics m ethod is featured

39、 of large p rospecting dep th, porta2 ble equipm ent and high lateral resolution. It has been w idely used in geothermal exp loration, hydro - geo2 logical exp loration, non - ferrous m ineral exp loration and engineering geological investigation, and satisfac2 tory field results have been obtained

40、in these area. However, few papers concerning the app lication of the m ethod have been published on publicly circula2 ted journals until now, and even fewer are the papers FOR GEO PHYS ICAL AND GEOCHEM ICAL EX PLO 2 4 ABSTRACTSVol 28 No. 4 . THE I PRO VEM ENT AND D EVELO PM ENT M O F THE M UL T I -

41、 FUNCT I N ASTAT I SO FT2 O C W ARE L I J ian 2xin, WANG Gui2cai, L I Chun 2 ing U U m ( School of Info - Physics Engineering, Center South University , Changsha 410083, China . COM PU T IN G TECHN IQU ES FOR GEO PHYS ICAL AND GEO 2 CHEM ICAL EX PLORA T ION , 2006, 28 ( 4 : 346 concerning the system

42、atic app lication of the m ethod. This paper describes some rep resentative field cases and results of the Controlled source audio - frequency magnetotellurics method. These cases basically cover the main app lication areas of the electric method and the works to which the conventional electric meth

43、od can not competent, which include fault basin geother2 mal resource and deep bedrock fracture water p ros2 pecting, deep m ineral exp loration in the near dep lete m ine, and geotechnical investigation over the comp lex terrain for railw ay tunnels . Key words: eletromagnetic soundings; geother al

44、 m resources; hydrogeology; non 2ferrous m ine; engineer2 ing geology; investigation THE PARALL EL COM PUTAT I N O F LA 2 O GRANGE M UL T IPL IER SEARCH ING IN M AG2 NETO TELL UR IC OCCAM INVERS I N O 1, 2 ( 11China University of Geoscience,W uhan L I Yu U Hubei 430074, China; 2. Guilin Institute of

45、 Technolo2 gy, Guilin Guangxi 541004, Chian . COM PU T IN G Occam inversion has been w idely used in magne2 totelluric data p rocessing for its convergence stability and independent of startup model, but the Lagrange multip lier ( searching result in too m any forward calculations and reduce the inv

46、ersion speed greatly . Based on discussing the calculation method of , the paper put forward using parallel computation to solve this p roblem and realized scanning and searching parallel computation w ith m aster - slave p rogramm ing mode. To reduce the comm unication and achieve load balancing, c

47、omputation tasks were arranged in group s and each grope were dispatched to different computation node. The examp le show s that parallel computation can speed up the p rocessing obviously . Key words: M T; occam inversion; one di ensional m search; parallel computation; COW The ASTATIC is an accord

48、ing p rocessing p ro2 gram of GDP system , which is used for the static TECHN IQU ES FOR GEO PHYS ICAL AND GEO 2 CHEM ICAL EX PLORA T ION , 2006, 28 ( 4 : 342 THE STUDY O F S IGNAL EST I AT I N FROM M O GRO UND PENETRATE RADAR DATA IN W AVEL ET DOM A IN INTERFERED BY W H ITE NO ISE Q I N ing, CHANG

49、Yan 2jun, CAO Zhong2lin ( Institu2 U te of Geophysics and Geom atics, China University of Geosciences, W uhan, 430074, China . COM PU T IN G Considering that the observed signals in ground penetrate radar data are som etim es polluted by noise, we introduce, in this paper, the app lication of smoot2

50、 hing factor in wavelet domain to esti ate available m signal from GPR data interfered by white noise, ac2 cording to wavelet analysis and fractal theory both havng identical p roperties in m ulti - scale analysis and self sim ilarity First, the signal w ith white noise . is transformed via the wavelet analysis filter into multi - scale subsystem s in tim e scale dom ain. Some non - station