推靠式旋轉(zhuǎn)導(dǎo)向鉆具力學(xué)性能研究

1、推靠式旋轉(zhuǎn)導(dǎo)向鉆具力學(xué)性能研究趙金海趙金洲韓來聚唐代緒(勝利石油管理局,山東東營(yíng)257000李子豐(燕山大學(xué),河北秦皇島066004摘要旋轉(zhuǎn)導(dǎo)向鉆井系統(tǒng)在大位移井中得到廣泛的應(yīng)用,該項(xiàng)技術(shù)國(guó)內(nèi)正處于研究階段。結(jié)合國(guó)家863項(xiàng)目“旋轉(zhuǎn)導(dǎo)向鉆井系統(tǒng)整體方案設(shè)計(jì)及關(guān)鍵技術(shù)研究”,對(duì)設(shè)計(jì)出的偏置式旋轉(zhuǎn)導(dǎo)向鉆具組合進(jìn)行了力學(xué)性能的理論研究,介紹了理論模型的建立和力學(xué)性能研究的部分結(jié)果,給出了推靠式旋轉(zhuǎn)導(dǎo)向鉆具的受力狀態(tài)分析、井眼曲率預(yù)測(cè)、導(dǎo)向穩(wěn)定器運(yùn)行參數(shù)、井眼曲率和方向與導(dǎo)向穩(wěn)定器偏心距和偏心方向的關(guān)系?？梢詾樾D(zhuǎn)導(dǎo)向穩(wěn)定器的設(shè)計(jì)提供理論依據(jù)。關(guān)鍵詞旋轉(zhuǎn)導(dǎo)向推靠式穩(wěn)定器力學(xué)性能井眼曲率預(yù)測(cè)隨著鉆井技術(shù)

2、的進(jìn)步,以控制井眼軌跡為目的的下部鉆具組合發(fā)展迅速,在原來的普通增斜、降斜和穩(wěn)斜鉆具的基礎(chǔ)上,發(fā)展并推廣了多種類型的導(dǎo)向鉆具、帶偏心彎接頭的防斜鉆具、帶柔性接頭防斜鉆具和兩穩(wěn)定器間變剛度的增斜鉆具等多種新型下部鉆具組合。20世紀(jì)末期研制出了旋轉(zhuǎn)導(dǎo)向鉆井系統(tǒng),該系統(tǒng)完全拋開了傳統(tǒng)的滑動(dòng)導(dǎo)向方式,而以旋轉(zhuǎn)導(dǎo)向鉆進(jìn)方式,自動(dòng)、靈活地調(diào)整井斜和方位,大幅度地提高了鉆井速度和鉆井安全性,軌跡控制精度也非常高,因此完全適合開發(fā)特殊油氣藏的超深井、大位移井、聰明井等特殊工藝井導(dǎo)向鉆井的需要,同時(shí)也是滿足閉環(huán)自動(dòng)鉆井發(fā)展需要的一種導(dǎo)向方式。目前,國(guó)際上已經(jīng)研制成功了多種旋轉(zhuǎn)導(dǎo)向鉆具。推靠式旋轉(zhuǎn)導(dǎo)向鉆具是在普通

3、旋轉(zhuǎn)鉆具的基礎(chǔ)上, 通過旋轉(zhuǎn)近鉆頭穩(wěn)定器,將鉆柱在旋轉(zhuǎn)過程中穩(wěn)定于井眼截面的需要位置,以控制井眼軌跡。為滿足攻關(guān)項(xiàng)目和現(xiàn)場(chǎng)作業(yè)的需要,建立了適用于旋轉(zhuǎn)導(dǎo)向鉆具進(jìn)行三維小撓度靜力學(xué)分析的數(shù)學(xué)模型,包括:微分方程;鉆頭、穩(wěn)定器、變截面、切點(diǎn)和井壁的邊界條件;鉆頭的側(cè)向力和鉆頭轉(zhuǎn)角;鉆具的導(dǎo)向能力與偏心距和偏心方向。編制了旋轉(zhuǎn)導(dǎo)向鉆具力學(xué)性能分析軟件,為旋轉(zhuǎn)導(dǎo)向鉆具的設(shè)計(jì)提供力學(xué)性能優(yōu)化設(shè)計(jì)工具,為旋轉(zhuǎn)導(dǎo)向鉆具的現(xiàn)場(chǎng)試驗(yàn)提供規(guī)律性的認(rèn)識(shí)與建議。1數(shù)學(xué)模型和加權(quán)余量解1.1數(shù)學(xué)模型為了建立推靠式旋轉(zhuǎn)導(dǎo)向鉆具力學(xué)模型,采用了一系列基本假設(shè),并建立了坐標(biāo)系統(tǒng)1。在推靠式旋轉(zhuǎn)導(dǎo)向下部鉆具組合中,如圖1所示,

4、可偏心的旋轉(zhuǎn)導(dǎo)向穩(wěn)定器安放在靠鉆頭位置,其后面串接1個(gè)或多個(gè)鉆柱穩(wěn)定器,為了減小上部的鉆柱力學(xué)性能對(duì)底部鉆具組合導(dǎo)向性能的影響,串接了1根柔性鉆具。在旋轉(zhuǎn)導(dǎo)向過程中,偏置工具的偏心產(chǎn)生的鉆頭側(cè)向力和鉆頭轉(zhuǎn)角起主要的導(dǎo)向作用。圖1推靠式旋轉(zhuǎn)導(dǎo)向下部鉆具組合圖1中的鉆具組合可視為縱橫彎曲梁柱,左端為鉆頭、右端為切點(diǎn),由n-1個(gè)穩(wěn)定器、變截面和接觸點(diǎn)分割成n個(gè)獨(dú)立結(jié)構(gòu)單元,處于三維彎曲井眼里,受自重、鉆壓、扭矩、井壁支撐反力及鉆井液靜水壓力等作用,產(chǎn)生空間彎曲變形。通過建立平衡方程、本構(gòu)方程和假設(shè)條件,推導(dǎo)出導(dǎo)向鉆具三維第26卷第1期石油鉆采工藝Vol.26No.12004年2月OI L DRI L

5、LI NG&PRODUCTI ON TECH NO LOGYFeb.2004基金項(xiàng)目:國(guó)家863項(xiàng)目,編號(hào):2001AA602013。作者簡(jiǎn)介:趙金海,1970年生。1996年7月畢業(yè)于西南石油學(xué)院,獲油氣井工程專業(yè)碩士學(xué)位,2000年12月獲得西南石油學(xué)院油氣井工程專業(yè)博士學(xué)位,現(xiàn)主要從事鉆井工藝技術(shù)服務(wù)和研究工作,鉆井所所長(zhǎng),高級(jí)工程師。電話3李子豐為第4作者。小撓度靜力分析微分方程組15。下部鉆具的邊界條件包括鉆頭、穩(wěn)定器、變截面、切點(diǎn)和井壁處的約束條件,其中穩(wěn)定器和變截面有與井壁接觸和非接觸2種狀態(tài)1。在可偏心的旋轉(zhuǎn)導(dǎo)向穩(wěn)定器處,在接觸井壁的情況下,

6、鉆柱位于井眼中心或在某一方向上偏離井眼中心一定距離,穩(wěn)定器兩側(cè)鉆柱的位移及其一次導(dǎo)數(shù)連續(xù)、彎矩連續(xù);在懸空狀態(tài)下,懸空穩(wěn)定器兩側(cè)鉆柱坐標(biāo)連續(xù)、導(dǎo)數(shù)連續(xù)、彎矩連續(xù)、內(nèi)力連續(xù)。為了研究和現(xiàn)場(chǎng)使用方便,做如下3個(gè)定義:偏斜角。以井眼的中心為原點(diǎn),從井眼中心原點(diǎn)開始向偏置工具偏出后鉆柱本體中心位置劃線為偏置方向指示線,以從井眼中心鉛垂向下劃線為0,逆時(shí)針轉(zhuǎn)動(dòng)到偏置方向指示線的角度稱為偏斜角。翼肋伸出方向角。從井眼中心原點(diǎn)開始向偏置工具偏出后鉆柱本體中心位置劃線為偏置方向,偏置方向的起點(diǎn)為從井眼中心原點(diǎn)鉛垂向上劃出的線為零點(diǎn),順時(shí)針旋轉(zhuǎn)到偏置工具偏出的方向之間的夾角。翼肋伸出方向是工具設(shè)計(jì)和施工控制中的

7、重點(diǎn)參考線。主法線方向。鉆具偏置后,形成的鉆頭側(cè)向力的方向,主法線方向的起點(diǎn)為從井眼中心原點(diǎn)鉛垂向上劃出的線為零點(diǎn),順時(shí)針旋轉(zhuǎn)到鉆頭側(cè)向力的方向之間的夾角。在常規(guī)井眼軌跡控制技術(shù)中也稱為工具面裝置角方向。1.2加權(quán)余量解1.2.1鉆具的增斜、增方位能力預(yù)測(cè)對(duì)于推靠式旋轉(zhuǎn)導(dǎo)向鉆具組合,當(dāng)?shù)谝环€(wěn)定器的偏心方向和偏心距等參數(shù)確定以后,它的增斜和增方位能力是一定的。該計(jì)算過程是尋找增斜率和增方位率,滿足V2x(k,k+V2y(k,k=0(1式中,V x、V y是鉆頭的側(cè)向運(yùn)動(dòng)速度分量。1.2.2旋轉(zhuǎn)導(dǎo)向工具工作狀態(tài)計(jì)算研制導(dǎo)向工具的過程為給定工具的增斜和增方位能力,確定偏置式導(dǎo)向穩(wěn)定器的偏心距和偏心方

8、向,同時(shí)給出該穩(wěn)定器與井壁的作用力(N x1,N y1。該計(jì)算過程是給定增斜率和增方位率(k,k,尋找滿足偏心距e c1、偏斜角1使得V2x(e c1,1+V2y(e c1,1=0(2 2鉆具的設(shè)計(jì)和導(dǎo)向性能分析2.1推靠式旋轉(zhuǎn)導(dǎo)向鉆具設(shè)計(jì)使用上述數(shù)學(xué)模型編制的計(jì)算軟件,設(shè)計(jì)出的推靠式旋轉(zhuǎn)導(dǎo)向穩(wěn)定器的規(guī)格如圖2所示,適用的井眼直徑為215.9mm,工具本體直徑為171mm,旋轉(zhuǎn)導(dǎo)向穩(wěn)定器在全縮回狀態(tài)下的直徑為202mm,最大偏心伸出量為10mm,則伸出后偏置式導(dǎo)向工具的中心偏離井眼軸線的偏心距為3.05mm,相對(duì)方的間隙為3.9mm。下部鉆具內(nèi)徑統(tǒng)一為90mm。設(shè)計(jì)出的推靠式旋轉(zhuǎn)導(dǎo)向鉆具如圖3

9、所示,偏置式旋轉(zhuǎn)導(dǎo)向工具安放在鉆頭上方0. 66m處,與上穩(wěn)定器(外徑212mm相隔3.49 m,其上面接10m的鉆鋌,鉆鋌外徑171mm,內(nèi)徑90mm,再往上串接 127mm 加重鉆桿做為柔性短接,根據(jù)導(dǎo)向需要接10200m 的鉆鋌,再往上接 127mm鉆桿。圖2旋轉(zhuǎn)導(dǎo)向穩(wěn)定器在朝135°工具面方向伸出10mm的情況下穩(wěn)定器和井眼的位置關(guān)系圖3設(shè)計(jì)的旋轉(zhuǎn)導(dǎo)向鉆具組合需要旋轉(zhuǎn)導(dǎo)向時(shí)的偏置力是這樣具體實(shí)現(xiàn)的,假如偏置工具的支撐翼肋要向135°工具面方向伸出,則推靠式旋轉(zhuǎn)導(dǎo)向穩(wěn)定器的支撐翼肋在轉(zhuǎn)到75°工具面方位時(shí)受穩(wěn)定平臺(tái)的控制而逐漸伸出,到135°工具面

10、時(shí)完全伸出,繼續(xù)旋轉(zhuǎn)則逐漸縮回,到195°工具面時(shí)全部縮回。這種條件下,偏置式旋轉(zhuǎn)導(dǎo)向工具和井眼之間的關(guān)系如圖2所示。2.2推靠式旋轉(zhuǎn)導(dǎo)向鉆具導(dǎo)向能力分析如圖3所示,設(shè)計(jì)的旋轉(zhuǎn)導(dǎo)向鉆具組合有穩(wěn)斜鉆進(jìn)和旋轉(zhuǎn)導(dǎo)向2種工作狀態(tài)。配接鉆具時(shí)區(qū)分有無柔性短接2種情況。穩(wěn)斜鉆進(jìn)時(shí)該鉆具支撐翼肋全縮回,即旋轉(zhuǎn)導(dǎo)向穩(wěn)定器無偏心,直徑為202mm。其它計(jì)算條件還有:井眼擴(kuò)大率0%,井斜角45°,主41石油鉆采工藝2004年2月(第26卷第1期法線方向0°,鉆頭各向異性指數(shù)0.3,鉆壓100kN,鉆井液密度為1.2g/cm3,鉆頭扭矩4kNm,計(jì)算結(jié)果如下。2.2.1旋轉(zhuǎn)導(dǎo)向穩(wěn)定器在

11、全縮回狀態(tài)下旋轉(zhuǎn)導(dǎo)向穩(wěn)定器在全縮回狀態(tài)下,只是近鉆頭穩(wěn)定器支撐翼肋全縮回,成為直徑為202mm的同心欠尺寸穩(wěn)定器,計(jì)算得到在原井眼是穩(wěn)斜的狀態(tài)下的造斜率為-0.25(°/25m,增方位率為-0.02(°/25m,接近穩(wěn)斜狀態(tài),導(dǎo)向穩(wěn)定器不和井壁接觸,上穩(wěn)定器和下井壁的接觸力為10.22kN,和右井壁的接觸力為-0.07kN。由此可見,設(shè)計(jì)的鉆具在全縮回狀態(tài)下具有穩(wěn)斜能力,具體的鉆具組合和鉆井參數(shù)在實(shí)鉆過程中做小井壁的接觸力為9.1kN范圍的組合調(diào)整,可滿足在全縮回狀態(tài)下穩(wěn)斜鉆進(jìn)的能力。2.2.2旋轉(zhuǎn)導(dǎo)向穩(wěn)定器在全增斜狀態(tài)下(1無柔性短接。如圖3所示的鉆具組合中無 127mm

12、加重鉆桿時(shí),增斜率為4.57(°/25m,增方位率為0.02(°/25m,此時(shí)導(dǎo)向穩(wěn)定器和下井壁的接觸力為9.1kN,和右井壁的接觸力為-0.12kN;上穩(wěn)定器和下井壁的接觸力為16.94kN,和右井壁的接觸力為-0.11kN。(2有柔性短接。如圖3所示的鉆具組合帶 127mm加重鉆桿時(shí),增斜率為5.18(°/25m,增方位率為0.13(°/25m,此時(shí)導(dǎo)向穩(wěn)定器和下井壁、右井壁的接觸力與無柔性短接相同;上穩(wěn)定器和下井壁的接觸力為11.82kN,和右井壁的接觸力為-0. 32kN。從上述計(jì)算結(jié)果看出,在其它鉆井參數(shù)、BH A 條件和井眼條件一致的情況下,

13、在第2個(gè)穩(wěn)定器上方增加1根柔性短接,可明顯提高鉆具的導(dǎo)向能力。有無柔性短接得到的增斜率計(jì)算結(jié)果均在設(shè)計(jì)的58.5(°/30m導(dǎo)向性能范圍內(nèi),而偏置式導(dǎo)向穩(wěn)定器和井壁的接觸力為9.1kN和11.82kN,在設(shè)計(jì)的支撐翼肋活塞推力范圍(18kN之內(nèi),在井下工具的實(shí)際下井工作過程中,通過調(diào)整鉆井參數(shù)和微調(diào)鉆具組合,完全可以滿足設(shè)計(jì)的導(dǎo)向性能。2.2.3該工具的旋轉(zhuǎn)導(dǎo)向特性將井斜角為45°,如圖3所示的旋轉(zhuǎn)導(dǎo)向鉆具在偏置式導(dǎo)向穩(wěn)定器支撐翼肋朝不同方向伸出時(shí)得到的增斜率和增方位率繪成圖表,如圖4所示,可以得到控制井眼軌跡時(shí)需要的控制位置,這些控制位置有明顯的規(guī)律性,連成一線可以得到規(guī)

14、則的圓形 。圖4推靠式旋轉(zhuǎn)導(dǎo)向鉆具的旋轉(zhuǎn)導(dǎo)向控制位置圖3結(jié)論與認(rèn)識(shí)(1所建立的數(shù)學(xué)模型比較客觀地描述了旋轉(zhuǎn)導(dǎo)向鉆具在井下的受力狀態(tài)。(2可以比較準(zhǔn)確地預(yù)測(cè)出旋轉(zhuǎn)導(dǎo)向鉆具的導(dǎo)向能力。(3分析結(jié)果可以指導(dǎo)旋轉(zhuǎn)導(dǎo)向鉆具的研制和改進(jìn)。(4推薦的偏置導(dǎo)向穩(wěn)定器及其鉆具組合具備設(shè)計(jì)的軌跡調(diào)整能力。參考文獻(xiàn)1李子豐.油氣井桿管柱力學(xué).北京:石油工業(yè)出版社,1996:49712李子豐,馬興瑞,黃文虎.鉆柱力學(xué)基本方程及其應(yīng)用.力學(xué)學(xué)報(bào),1995,27(4:4064143李子豐.井眼軌道控制理論.北京:石油工業(yè)出版社,1996:9724李子豐,劉希圣.導(dǎo)向鉆具組合三維小撓度力學(xué)分析.石油鉆探技術(shù),1993,21

15、(2:165周大千.井眼軌道實(shí)用理論基礎(chǔ).北京:石油工業(yè)出版社,1993:751426李子豐,劉希圣.下部鉆具三維大撓度靜力分析.石油大學(xué)學(xué)報(bào)(自然科學(xué)版,1994,18(4:37427Li Z ifeng,Ma X ingrui,Huang Wenhu.3D Analysis of Bot2tom H ole Assembly Under Large Deflection.SPE Drilling&C ompletion,1996,11(2:1041108李子豐,李敬元,馬興瑞.油氣井桿管柱動(dòng)力學(xué)基本方程及應(yīng)用.石油學(xué)報(bào),1999,20(3:8790(收稿日期2003204208編輯

16、薛改珍51趙金海等:推靠式旋轉(zhuǎn)導(dǎo)向鉆具力學(xué)性能研究OI L DRI LLING&PRODUCTION TECHNOLOG YV ol.26N o.1Feb2004ABSTRACTSTU DY ON DRI LL BIT SE LECTIONS FOR XI2 JIANG EXTEN DE D-REACH WE LLS IN SOUTH CHINA SEAby G ao Deli,Pan Qifeng,(University of Petroleum;Zhang WunianAbstractIn this article,the evaluation results of rock me

17、chanics parameters of X J24-1oil field are given by operations on S oftware for R ock Mechanics Analysis and Drill Bit Selections based on the electrical logging data as input.The anti-drilling characteristics of the formations is illustrated with the help of the above re2 sults,which shows rock str

18、ength and abrasiveness in2 creasing with hole depth and the formation is difficult to be drilled.Base on the analysis,several appropriate drill bit types are recommended for drilling into the formations in X J24-1oil field and are of g ood performances while drilling into the extended-reach wells in

19、 this oil field.K ey w ordsERW(Extended Reached Wellrock mechanics parameters drill bit selection well logging data COMP LETION TECHN OLOG Y OF THE FIRST TAML5DOUB LE LATERA L WE LL AT H OME by Jiang Zujun(S outh West Petroleum Bureau of SI NOPECAbstractA set of com pletion technology and aux2 iliar

20、y tools for multi-lateral well is developed accord2 ing to such geological characteristics as multiple produc2 tion zones,high pressure gradients,dense formation and variability of litbology,etc in west Sichuan area.With the help of the auxiliary tools,the dynamic integrity and mechanical stability

21、at the junction of main hole with branch hole may be achieved;both the main hole and the branch are cemented,and then squeeze sealing fluid at the window,thus m ore reliable hydraulic seal can be achieved at the junction of main hole with branch hole.A orienting facility is pre-set in the com pletio

22、n string, which ensures the accuracy,continuity and sim plicity of the branch hole orientation;by applying auto-position2 ing and orientating tool,the re-entrance of each branch is ensured;by using the premilled casing and hollow whipstock,the communication between the main hole and branch is then e

23、stablished;zonal pressure is olation and separated fracturing and producing can be achieved through dual tubing string and dual packer.These tech2 nologies were success fully used in Well X inqian-90, which is double lateral well,and its com pletion level reached T AM LS.K ey w ordsChuanxi area natu

24、ral gas lateral well com pletion well technologyDISCUSSION OF MECHANISM OF THE LEAK2 AGE AN D JU MPE D-OUT ABOUT THE THREADS OF CASING CONNECTORby Lian Zhanghua,Liu Y onggang,T ang Bo,( S outhwest Petroleum Institute;Y ang Long;Han Jianzeng,Zhang Y iAbstractUnder the deep well,extra-deep well,extend

25、 well and horizontal well,the properties of the leakage and jum ped-out of the casing connector is the topic that is studied forever at home and abroad in the research of the oil-gas pipeline mechanics.Based on the study of many literatures,the develop object of the premium connections was presented

26、 in the paper,the mechanism of the leakage and jum ped-out of the threads of casing connection was discussed in detail.The stresses of the connection of the buttress and round threads were analyzed with finite element method( FE M,the curves of the jum ped-out loads varied with the time was obtained

27、 when the flank angles of the but2 tress are3°,5°and10°degreed,respectively.With the three tapers1/14,1/16and1/17,for the round casing connector,the curves that the jum p-out loads varied with the loading process were obtained.It provides the theoretical supports for the selection of

28、the casing con2 nectors in the extra-deep well and com plex well.K ey w ordscasing connection thread deep well leakage and jum ped-out FE M mechanism studySTU DY ON MECHANICA L PR OPERT Y OF PUSH -THE-BIT R OTAR Y STEERING BHAby Zhao Jinhai,Zhao Jinzhou,Han Laiju,( Shengli Oil Administration Bureau;

29、Li Z ifeng;T ang DaixuAbstractAlong with the progress of drilling tech2 nology,bottom hole assembly developed rapidly to control well trajectory.R otary steering bottom hole assembly is the m ost advanced.Bottom hole assembly studied in this paper is set rotating steering stabilizer in a comm on rot

30、ate bottom hole assembly to control well path.T o develop and use this bottom assembly,this paper provides me2 chanical analysis of rotary steering BH A,the mathemati2 cal m odel includes forces analysis of rotary steering BH A,BUR calculating,con figuration of steering stabi218Vol.26No.1ABSTRACTliz

31、er and controlling positions of steering stabilizer.This paper provides theory basis for the design of rotary steer2 ing stabilizer.K ey w ordsrotary steering push-the-bit sta2 bilizer mechanical analysis BUR calculationSTU DIES ON SLANTING CONTR OL&FAST DRI LLING BHA IN THE OVERTHRUST NAPPE FOR

32、 MATIONby He Weibin,Wang Lei,Y u Chengshui, (Drilling and Production T echnology Research Inst.of Dagang Oilfield G roup C om pany;Lin Y ushuiAbstractC onventional pendulum drill-assembly is not efficient enough in drilling the over-thrust nappe formation which is slant and hard and causes such prob

33、lems as bit jum ping and drill tool friction;while only light W OB could be applied when drilling the hard for2 mation which severely limits the penetration rate and adds up to the drilling cost.This paper focuses on the experimental application of several drill-assemblies when drilling the 311mm ho

34、le in the over-thrust nappe in Well Qiong-9,specifically these assemblies are angle-holding assembly with multiple stabilizers and MW D plus steerable drill,eccentric drill and suspended drilling.Results show that all the three assemblies can im prove ROP by applying high W OB,however,hole de2 viati

35、on control remains a problem.P ossible causes of poor deviation control are analyzed and eccentric drill should be used;it is als o an ideal alternative to drill di2 rectional well and extended reach well by taking the ad2 vantage of the natural slanting tendency in such forma2 tion.K ey w ordsQingx

36、i Oilfield overthrust nappe slanting control fast drilling suspending drilling RESEARCH ON THE FAI L URE MECHANISM AN D FATIGUE LIFE PRE DICTION OF DRI LLPIPEby Lin Y uanhua(S outhwest Petroleum Institute; Luo H ongzhi,Zhou Bo,Shi T aihe,Weng X iaohong,Li Run fangAbstractThe w orking condition of dr

37、illpipe is very serious,especially in the dogleg or build section. Large alterative bending stress gives rise to the fatigue failure of drillpipe.Calculation of the fatigue life of the drillpipe can give s ome guidance for the use and precau2 tion of drillpipe failure.As a result,in this paper,the t

38、hree-axis stress has been analyzed based on the mechanism of fatigue failure of drillpipe,and a m odel for the calculation of fatigue life of drillpipe is proposed, which can be used for the prediction of fatigue life of crackled or noncrackled drillpipe.Results of exam ple show that the m odel is r

39、eas onable and coincident with the field data.K ey w ordsfatigue Life drillpipe Failure Mecha2 nism Crack predictCEMENTING EVA L UATION ON U LTRA-DEEP WE LL KU-1IN TAHE OI LFIE LDby Zhao Fengsen,Y ang Z ichao,Zhang H ong wei, (North West Branch C om pany of SI NOPECAbstractWith the enhancement of ex

40、ploration and development in T ahe Oilfield,m ore ultra-deep exploration wells of over6000m in depth are drilled in the lower Ordovician formation.T o im prove cementing quality and expand the exploration achievements,a m ost representative well K U-1is selected as an exam ple for evaluation.The eva

41、luation focuses on hole condition dif2 ficulties presentation before cementing each section of casing,operation process description,successes and failures of cementing operations,etc.T echnical features and difficuhies in cementing operations of T ahe Oilfield are presented,and it is pointed out that the present tech2 nology level can meet the cementing requirements in ultra -deep wells,while there are still s ome aspects to be im proved.S ome suggestions and methods are als o brought out and can be used as refere