油套管安全性评估
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摘要
在石油化工等生产中，套管担负着固井的任务，在生产中占有及其重要的地位。一旦发生事故，就会危及正常生产，甚至可能引起火灾、中毒、爆炸等恶性事故。做好油气管道的失效分析及预防工作，对我国石油和管道工业的发展，具有重要的意义。
首先，简要阐述了管道剩余强度评价技术的发展背景、研究现状，提出了研究目标和研究内容。
接着介绍了剩余强度评价力学理论基础和评价原则，归纳整理了含裂纹管道的剩余强度的工程评定方法，为论文研究含裂纹型缺陷套管的剩余强度提供工程规范依据。
然后应用断裂力学理论推导了几种典型缺陷和外载作用下的应力强度因子表达式，运用Maple语言编程分别算出周向外表面裂纹和轴向内表面裂纹的应力强度因子形状系数的无量钢值，分析了形状系数的变化趋势和影响因素。结合工程应用实例—N80套管(Φ5.5″×0.361″)，按照结构剩余强度评价的工程规范要求，应用英国中央电力局(CEGB)的R6方法，对其剩余强度进行评估，确定相应的安全边界。系统探讨了内压和轴向载荷对套管剩余强度的影响，给出了相应的参数，揭示了剩余强度随内压、轴向载荷变化的关系，也为现场评估提供了方便。
接下来，在现有评价方法的基础上，以管道最大允许操作压力为评价出发点，结合实例—N80套管(Φ5.5″×0.361″)，依据美国石油协会(API)的“石油天然气工业适用性评价标准推荐做法”中的一级评价方法和采用ANSYS有限元分析软件，分别计算了不同凹坑深度下套管的极限载荷。系统讨论了内压对含凹坑缺陷的套管的剩余强度的影响，并将一级评价方法与有限元方法的计算结果进行了比较，分析了两者的差别，指出了一级评价方法的不足。
最后，考虑评价参数的不确定性，运用Monte Carlo方法，分别建立了基于FAD技术的含裂纹型缺陷套管和基于API 579一级评价方法的含体积型缺陷套管的失效概率的计算模型。并结合工程实例，给出了一个含缺陷压力容器在多种失效模式下的失效概率的定量计算结果，真实地反映了含缺陷结构的安全状态。
The oil thimble is very important in the exploitation of petroleum. Defects in a thimble are usually ge (?)erated in construction and operation. The residual strength of the oil thimble defeated must be evaluated so that the correct decisions can be made: the thimble can continue to service, require to be maintained or must to be replaced.
Firstly, this paper sets forth in the scientific basis , development background and present research situation of the residual strength assessment technology of oil thimble. Then it puts forward the study intention and detailed study containing and also frames the proper technique courses.
The exterior surface crack is the most dangerous among crack defects of oil thimble. The common assessment methods, including the limit load method and fracture mechanics method are discussed and the developing trend of the research on assessment methods is analyzed. Then the energy difference rate method is applied to obtain a simplified closed form solution of the Bernauli's equation about crack opening displacement, which is ultimately deduced in the oil thimble with semi-ellipse outer surface crack or inner surface crack under the a (?)al traction load. For casingΦ5.5"×0.361",Maple language is used to compute non-dimensional values of shape factor of stress intensity factor .On the basis of this, residual strength assessment has been conducted by use of the R6 section l(CEGB). The corresponding security boundary is determined and the influence of pressure and the axial load on the remaining strength has been Systematically analyzed which is convenient for engineering application.
Then the API 579 formula Level 1,given by recommendation procedure of fitness for service criterion in petroleum and gas industry by API ,and the finite element analysis were performed on the load-carrying capability of a pressurized oil thimble with defects in the outer surface. Finite element models were established for the pressurized pipe of Φ5.5"×0.361" in outer diameter with pit defects in the outer surface. Strength analysis and calculation of the limit load were carried out based on the pressure vessel code of design by analysis. Finally, difference between API 579 formula and finite element method is proposed and the reason in analyzed. Finally, indefinity of the parameters is considered. Based on the FAD technology and API 579 formula, the .failure probability computation model of the oil thimble containing the crack and the volume defeats are established according to Monte Carlo method. At last, a typical pressure vessel containing complex defeats is involved and the failure probability is calculated. This result really reflected the secure state..
首先，简要阐述了管道剩余强度评价技术的发展背景、研究现状，提出了研究目标和研究内容。
接着介绍了剩余强度评价力学理论基础和评价原则，归纳整理了含裂纹管道的剩余强度的工程评定方法，为论文研究含裂纹型缺陷套管的剩余强度提供工程规范依据。
然后应用断裂力学理论推导了几种典型缺陷和外载作用下的应力强度因子表达式，运用Maple语言编程分别算出周向外表面裂纹和轴向内表面裂纹的应力强度因子形状系数的无量钢值，分析了形状系数的变化趋势和影响因素。结合工程应用实例—N80套管(Φ5.5″×0.361″)，按照结构剩余强度评价的工程规范要求，应用英国中央电力局(CEGB)的R6方法，对其剩余强度进行评估，确定相应的安全边界。系统探讨了内压和轴向载荷对套管剩余强度的影响，给出了相应的参数，揭示了剩余强度随内压、轴向载荷变化的关系，也为现场评估提供了方便。
接下来，在现有评价方法的基础上，以管道最大允许操作压力为评价出发点，结合实例—N80套管(Φ5.5″×0.361″)，依据美国石油协会(API)的“石油天然气工业适用性评价标准推荐做法”中的一级评价方法和采用ANSYS有限元分析软件，分别计算了不同凹坑深度下套管的极限载荷。系统讨论了内压对含凹坑缺陷的套管的剩余强度的影响，并将一级评价方法与有限元方法的计算结果进行了比较，分析了两者的差别，指出了一级评价方法的不足。
最后，考虑评价参数的不确定性，运用Monte Carlo方法，分别建立了基于FAD技术的含裂纹型缺陷套管和基于API 579一级评价方法的含体积型缺陷套管的失效概率的计算模型。并结合工程实例，给出了一个含缺陷压力容器在多种失效模式下的失效概率的定量计算结果，真实地反映了含缺陷结构的安全状态。
The oil thimble is very important in the exploitation of petroleum. Defects in a thimble are usually ge (?)erated in construction and operation. The residual strength of the oil thimble defeated must be evaluated so that the correct decisions can be made: the thimble can continue to service, require to be maintained or must to be replaced.
Firstly, this paper sets forth in the scientific basis , development background and present research situation of the residual strength assessment technology of oil thimble. Then it puts forward the study intention and detailed study containing and also frames the proper technique courses.
The exterior surface crack is the most dangerous among crack defects of oil thimble. The common assessment methods, including the limit load method and fracture mechanics method are discussed and the developing trend of the research on assessment methods is analyzed. Then the energy difference rate method is applied to obtain a simplified closed form solution of the Bernauli's equation about crack opening displacement, which is ultimately deduced in the oil thimble with semi-ellipse outer surface crack or inner surface crack under the a (?)al traction load. For casingΦ5.5"×0.361",Maple language is used to compute non-dimensional values of shape factor of stress intensity factor .On the basis of this, residual strength assessment has been conducted by use of the R6 section l(CEGB). The corresponding security boundary is determined and the influence of pressure and the axial load on the remaining strength has been Systematically analyzed which is convenient for engineering application.
Then the API 579 formula Level 1,given by recommendation procedure of fitness for service criterion in petroleum and gas industry by API ,and the finite element analysis were performed on the load-carrying capability of a pressurized oil thimble with defects in the outer surface. Finite element models were established for the pressurized pipe of Φ5.5"×0.361" in outer diameter with pit defects in the outer surface. Strength analysis and calculation of the limit load were carried out based on the pressure vessel code of design by analysis. Finally, difference between API 579 formula and finite element method is proposed and the reason in analyzed. Finally, indefinity of the parameters is considered. Based on the FAD technology and API 579 formula, the .failure probability computation model of the oil thimble containing the crack and the volume defeats are established according to Monte Carlo method. At last, a typical pressure vessel containing complex defeats is involved and the failure probability is calculated. This result really reflected the secure state..
引文
[1] 李鹤林，吉玲康，谢丽华，中国石油钢管的发展现状分析．河北科技大学学报．2006(3)：2～5
[2] 在用工业管道定期检验规程(试行)．国家质量监督检验检疫总局文件．2003．4
[3] 华东化工学院化工机械研究所译．CEGB／H／R6第三版，有缺陷结构完整性评定标准[s]，1986．6
[4] API.API 579: Recommended practice for fitness-for service[S]. Washington, DC: American Petroleum Institute, 2000
[5] WEE/37. Guide on Methoods for Assessing the Acceptability of Flaws in Metallic Structures,BS7910-99
[6] BRITE EURAM Project. Structural Integrity Assessment Procedure for European Industry-SINTAP, Procedure Document, Rotherham, UK: British Steel(now Corus Group) Swinden Technology Centre. 1999
[7] 王威强，钝裂纹或缺口下失效评定图的变化及修正方法研究．机械工程学报，1999，35(4)，15～20
[8] 金志江，应变区准三维模型失效评定曲线FAC的研究．工程设计学报．1999，(3)：44～47
[9] 轩福贞，涂善东，王正东，高温含缺陷结构与时间相关的失效评定图．核动力工程．2003，24(6)：508～513
[10] 帅健，辛艳霞，基于失效评定图的油气管线可靠性分析．天然气工业．2002，22(2)：83～86
[11] 王晓春，杨铁成，倾斜裂纹的失效评定图．压力容器．2000，17(5)：1～4，22
[12] 刘应华，岑章志，含缺陷结构的塑性极限分析．固体力学学报．1999，20(3)：211～218
[13] 张红才，李培宁，陈代清球形封头上结构不连续处凹坑极限载荷分析．石油化工设备．2003，32(6)：30～32
[14] 朱健斌，郑敏荣，含气孔缺陷球形压力容器极限载荷的研究．石油机械．2002，30(10)：9～11
[15] 于红艳，含裂纹结构的极限载荷分析方法研究．西安：西北工业大学硕士学位论文，2002．4
[16] 署恒木，李继志．含有裂纹管道剩余强度的评价方法．石油机械，2000，28(7)：51～543
[17] Ahammed M. Prediction of remaining strength of corroded pressuried pipelines.Int.J Ves.& Piping, 1997,71:213,217
[18] Liu Y H, Carveill V, Maier G. Integrity assessment of defective pressurized pipelines by direct simplified methods.Int.J Ves.& Piping, 1997,74:49～57
[19] 尹双增，断裂损伤理论及应用．清华大学出版社．1992
[20] 赵新伟，路民旭，白真权等．含裂纹管道生育强度评价方法及其应用．石油矿场机械。1999，28(3)：24～28
[21] 李强．Maple8基础应用教程．中国水利水电出版社。2004
[22] Newman JC,Raju I S. Stress intensity factor equations for cracks in three dimensional finite bodies. Fracture Me-chanics-Vol. Ⅰ:Theory and Analysis,ASTM STP-791, 1983, 238-269
[23] Chen Zhi Gang, Zhang Xing, A Colssed Form Solution of Stress Intensity Factor about a Circular Tube with a Surface Crack by Engergy Release Rate Method, Engineering Fracture Machanics, Vol.32, No.4, 639-652, 1989
[24] Newman, J. C. Jr., and Raji, I.S ., Stress-Intensity Factors for internal Surface Cracks in Cylindrical Pressure Vessels Trans. ASME, J. Pressure Vessel Technology 102, 342-346, 1980
[25] 赵新伟等．油气管道检测与完整性评价技术．西安：中国石油天然气集团管材研究所，2004
[26] 徐颖强，原园，吕国志等．含凹坑缺陷在役石油管道剩余极限强度分析．石油机械．2004，32(10)：11～13，22
[27] 刘应华，含凹坑缺陷圆柱壳的数值极限分析．力学学报，1996，28(6)：682～6914
[28] 白洁，含凹坑缺陷压力管道的塑性极限分析．清华大学学报，2002．42
[29] 沈士明等．压力管道缺陷评定方法的现状与发展．南京化工大学学报．1999．1
[30] 赵新伟，罗金恒，路民旭．2001．含腐蚀缺陷管道剩余强度的有限元分析．油气储运．20(3)：18～21．
[31] 赵新伟，路民旭，白真权等．管道腐蚀剩余强度评价．油气储运．1999 18(11)：34～37．
[32] 董保胜，赵新伟，韩晓毅等．含体积型缺陷管道剩余强度的计算与试验．油气储运．2004，23(5)：27～30
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[2] 在用工业管道定期检验规程(试行)．国家质量监督检验检疫总局文件．2003．4
[3] 华东化工学院化工机械研究所译．CEGB／H／R6第三版，有缺陷结构完整性评定标准[s]，1986．6
[4] API.API 579: Recommended practice for fitness-for service[S]. Washington, DC: American Petroleum Institute, 2000
[5] WEE/37. Guide on Methoods for Assessing the Acceptability of Flaws in Metallic Structures,BS7910-99
[6] BRITE EURAM Project. Structural Integrity Assessment Procedure for European Industry-SINTAP, Procedure Document, Rotherham, UK: British Steel(now Corus Group) Swinden Technology Centre. 1999
[7] 王威强，钝裂纹或缺口下失效评定图的变化及修正方法研究．机械工程学报，1999，35(4)，15～20
[8] 金志江，应变区准三维模型失效评定曲线FAC的研究．工程设计学报．1999，(3)：44～47
[9] 轩福贞，涂善东，王正东，高温含缺陷结构与时间相关的失效评定图．核动力工程．2003，24(6)：508～513
[10] 帅健，辛艳霞，基于失效评定图的油气管线可靠性分析．天然气工业．2002，22(2)：83～86
[11] 王晓春，杨铁成，倾斜裂纹的失效评定图．压力容器．2000，17(5)：1～4，22
[12] 刘应华，岑章志，含缺陷结构的塑性极限分析．固体力学学报．1999，20(3)：211～218
[13] 张红才，李培宁，陈代清球形封头上结构不连续处凹坑极限载荷分析．石油化工设备．2003，32(6)：30～32
[14] 朱健斌，郑敏荣，含气孔缺陷球形压力容器极限载荷的研究．石油机械．2002，30(10)：9～11
[15] 于红艳，含裂纹结构的极限载荷分析方法研究．西安：西北工业大学硕士学位论文，2002．4
[16] 署恒木，李继志．含有裂纹管道剩余强度的评价方法．石油机械，2000，28(7)：51～543
[17] Ahammed M. Prediction of remaining strength of corroded pressuried pipelines.Int.J Ves.& Piping, 1997,71:213,217
[18] Liu Y H, Carveill V, Maier G. Integrity assessment of defective pressurized pipelines by direct simplified methods.Int.J Ves.& Piping, 1997,74:49～57
[19] 尹双增，断裂损伤理论及应用．清华大学出版社．1992
[20] 赵新伟，路民旭，白真权等．含裂纹管道生育强度评价方法及其应用．石油矿场机械。1999，28(3)：24～28
[21] 李强．Maple8基础应用教程．中国水利水电出版社。2004
[22] Newman JC,Raju I S. Stress intensity factor equations for cracks in three dimensional finite bodies. Fracture Me-chanics-Vol. Ⅰ:Theory and Analysis,ASTM STP-791, 1983, 238-269
[23] Chen Zhi Gang, Zhang Xing, A Colssed Form Solution of Stress Intensity Factor about a Circular Tube with a Surface Crack by Engergy Release Rate Method, Engineering Fracture Machanics, Vol.32, No.4, 639-652, 1989
[24] Newman, J. C. Jr., and Raji, I.S ., Stress-Intensity Factors for internal Surface Cracks in Cylindrical Pressure Vessels Trans. ASME, J. Pressure Vessel Technology 102, 342-346, 1980
[25] 赵新伟等．油气管道检测与完整性评价技术．西安：中国石油天然气集团管材研究所，2004
[26] 徐颖强，原园，吕国志等．含凹坑缺陷在役石油管道剩余极限强度分析．石油机械．2004，32(10)：11～13，22
[27] 刘应华，含凹坑缺陷圆柱壳的数值极限分析．力学学报，1996，28(6)：682～6914
[28] 白洁，含凹坑缺陷压力管道的塑性极限分析．清华大学学报，2002．42
[29] 沈士明等．压力管道缺陷评定方法的现状与发展．南京化工大学学报．1999．1
[30] 赵新伟，罗金恒，路民旭．2001．含腐蚀缺陷管道剩余强度的有限元分析．油气储运．20(3)：18～21．
[31] 赵新伟，路民旭，白真权等．管道腐蚀剩余强度评价．油气储运．1999 18(11)：34～37．
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