基于分项系数法的套管实用可靠度设计方法
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摘要
针对套管服役过程中几何尺寸、力学性能和所承受荷载作用随机性和时变性的特点,结合ISO2394、EN1990、GB50153等国内外结构可靠度设计统一标准,提出了一种基于分项系数方法的套管可靠度设计的实用方法。该方法依据固井水泥环固结前后套管荷载组合形式的差异性和套管强度的折减,将套管整个服役过程分为钻完井阶段和生产阶段,分别建立了上述2个阶段的套管强度设计极限状态方程。考虑荷载和强度的变异系数对套管设计值的影响,采用可靠度理论分别计算套管荷载和强度的分项系数,实现了套管服役期间的可靠度定量表述,可以有效预测套管在整个服役期间的安全可靠性能。计算结果表明:管材强度变异系数对设计结果的影响要远大于荷载变异系数,在设计时应注意选择性质稳定、强度变异系数小的管材。通过与SY/T5724的设计结果相比较,基于分项系数法的分阶段强度可靠度设计方法可以满足工程套管强度的实际需要。
Aiming at the randomness and time-varying characteristics of geometry size,mechanical property and bearing load during casing service process,apractical method is put forward for reliability design of casing based on partial coefficient method in combination with ISO2394,EN1990,GB50153 and other domestic and foreign unified standards for structural reliability design.Based on the differences in casing load combinations and the degradation of casing strength prior and posterior to cement sheath consolidation,the casing service process is divided into two stages using the above method,i.e.,drilling/completion stage and production stage,based on which the limit state equations of casing strength design in the above two stages are established respectively.Taking into account the influences of load and strength variation coefficients on casing design values,the reliability theory was used to calculate the partial coefficients of casing load and strength,and achieve the quantitative expression of reliability in the casing service process,thus effectively predicting the safe reliability of casing in the whole service process.Calculation results show that casing strength variation coefficient has rather higher impacts on design results than load variation coefficient.In the design stage,the casings with property stability and low strength variation coefficient should be selected.Compared with the design results of SY/T5724,the staged strength reliability design method based on partial coefficient method is able to meet the practical strength demand for engineering casing.
Aiming at the randomness and time-varying characteristics of geometry size,mechanical property and bearing load during casing service process,apractical method is put forward for reliability design of casing based on partial coefficient method in combination with ISO2394,EN1990,GB50153 and other domestic and foreign unified standards for structural reliability design.Based on the differences in casing load combinations and the degradation of casing strength prior and posterior to cement sheath consolidation,the casing service process is divided into two stages using the above method,i.e.,drilling/completion stage and production stage,based on which the limit state equations of casing strength design in the above two stages are established respectively.Taking into account the influences of load and strength variation coefficients on casing design values,the reliability theory was used to calculate the partial coefficients of casing load and strength,and achieve the quantitative expression of reliability in the casing service process,thus effectively predicting the safe reliability of casing in the whole service process.Calculation results show that casing strength variation coefficient has rather higher impacts on design results than load variation coefficient.In the design stage,the casings with property stability and low strength variation coefficient should be selected.Compared with the design results of SY/T5724,the staged strength reliability design method based on partial coefficient method is able to meet the practical strength demand for engineering casing.
引文
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[17]国际结构安全度联合委员会.概率模式规范[S].国际结构安全度联合委员会,2011.JCSS.Probability model specification[S].The Joint Committee on International Structure Safety,2011
[18]蔡春源.机械零件设计手册[M].北京:冶金工业出版社,1995.Cai Chunyuan.Mechanical parts design manual[M].Beijing:Metallurgical Industry Press,1995.
[19]殷有泉,李平恩.非均匀载荷下套管强度的计算[J].石油学报,2007,28(6):138-146.Yin Youquan,Li Ping’en.Computation of casing strength under non-uniform load[J].Acta Petrolei Sinica,2007,28(6):138-146.
[20]廖华林,管志川,马广军,等.深井超深井内壁磨损套管剩余强度计算[J].工程力学,2010,27(2):250-255.Liao Hualin,Guan Zhichuan,Ma Guangjun,et al.Remaining strength calculation of internal wall worn casing in deep and ultra-deep wells[J].Engineering Mechanics,2010,27(2):250-255.
[21]Adams A J,Parfitt S H L,Reeves T B,et al.Casing system risk analysis using structural reliability[R].SPE25693,1993.
[22]Galambos T V,Ravindra M K.Properties of steel for use in LRFD[J].Journal of the Structural Engineering Division,ASCE,1978,104(9):1459-1468.
[23]中华人民共和国住房和城乡建设部.GB50009-2012建筑结构荷载规范[S].北京:中国建筑工业出版社,2012.Ministry of Housing and Urban-Rural Development of the People’s Republic of China.GB50009-2012 Load code for the design of building structures[S].Beijing:China Architecture&Building Press,2012.
[2]廖华林,管志川,闫振来,等.基于可靠性理论的套管失效风险评价方法[J].石油学报,2010,31(1):161-164.Liao Hualin,Guan Zhichuan,Yan Zhenlai,et al.The casing failure risk assessment method based on reliability theory[J].Acta Petrolei Sinica,2010,31(1):161-164.
[3]高进伟,闫相祯,杨秀娟,等.用可靠性理论分析传统套管设计中存在的问题[J].中国石油大学学报:自然科学版,2006,30(5):79-83.Gao Jinwei,Yan Xiangzhen,Yang Xiujuan,et al.Analysis of API formulas and calculation of casing strength based on reliability theory[J].Journal of China University of Petroleum:Edition of Natural Science,2006,30(5):79-83.
[4]高进伟.复杂井况下套管的可靠性与风险评估研究[D].东营:中国石油大学(华东),2007.Gao Jinwei.Study on reliability and risk assessment of casing in complex well status[D].Dongying:China University of Petroleum(East China),2007.
[5]杨平阁.辽河油田井筒完整性现状与研究[C]∥油气井管柱与管材国际会议(2014)论文集.西安,2014.Yang Pingge.The study on wellbore integrity of Liaohe oilfield[C]∥The present situation and the oil and gas well tubing string and tubing proceedings of international conference(2014).Xi’an,2014.
[6]龙刚,李猛,管志川,等.深井套管安全可靠性评价方法[J].石油钻探技术,2013,41(4):48-53.Long Gang,Li Meng,Guan Zhichuan,et al.Evaluation method of casing safety and reliability in deep wells[J].Petroleum Drilling Techniques,2013,41(4):48-53.
[7]Thoft-Christensen P,Baker M J.Structural reliability theory and its applications[M].New York:Springer-Verlag,1982:51-52.
[8]Liang Q J.Application of quantitative risk analysis to pore pressure and fracture gradient prediction[R].SPE77354,2002.
[9]许志倩,闫相祯,杨秀娟,等.复杂井况下油井套管柱的系统可靠性计算[J].中国石油大学学报:自然科学版,2009,33(4):125-129.Xu Zhiqian,Yan Xiangzhen,Yang Xiujuan,et al.Calculation of casing system reliability in complex well condition[J].Journal of China University of Petroleum:Edition of Natural Science,2009,33(4):125-129.
[10]练章华.地应力与套管损坏机理[M].北京:石油工业出版社,2009.Lian Zhanghua.Ground stress and the mechanism of casing damage[M].Beijing:Petroleum Industry Press,2009.
[11]许志倩,闫相祯,杨秀娟,等.微观泄露机理在非API套管接头密封性能评估中的应用[J].石油学报,2014,35(5):963-971.Xu Zhiqian,Yan Xiangzhen,Yang Xiujuan,et al.Aplication of microleakage mechanism for evaluating the sealing performance of non-API casing connections[J].Acta Petrolei Sinica,2014,35(5):963-971.
[12]翟晓鹏,楼一珊,曹砚峰,等.蠕变岩层地层刚度和松弛时间对套管外挤力的影响[J].石油学报,2015,36(10):1299-1304.Zhai Xiaopeng,Lou Yishan,Cao Yanfeng,et al.Influences of stratum stiffness and relaxation time of creep layers on external squeeze pressure of casing[J].Acta Petrolei Sinica,2015,36(10):1299-1304.
[13]国家发展和改革委员会.SY/T5724-2008套管柱结构与强度设计[S].北京:石油工业出版社,2008.National Development and Reform Commission.SY/T5724-2008Design method of casing string strength[S].Beijing:Petroleum Industry Press,2008.
[14]国际标准化组织设计基础委员会.ISO2394结构可靠性总原则[S].国际标准化组织,1996.The International Standard.The general principle of structuralreliability(ISO2394)[S].International Organization for Standardization,1996.
[15]“结构欧洲规范”技术委员会.欧洲规范—结构设计基础[S].欧洲标准化委员会,1990.CEN/T250.Eurocode—Basis of structural design[S].The European Committee for Standardization,1990.
[16]中华人民共和国住房和城乡建设部.GB50153-2008工程结构可靠性设计统一标准[S].北京:中国建筑工业出版社,2008.Ministry of Housing and Urban-Rural Development of the People’s Republic of China.GB50153-2008 Unified standard for reliability design of engineering structures[S].Beijing:China Architecture&Building Press,2008.
[17]国际结构安全度联合委员会.概率模式规范[S].国际结构安全度联合委员会,2011.JCSS.Probability model specification[S].The Joint Committee on International Structure Safety,2011
[18]蔡春源.机械零件设计手册[M].北京:冶金工业出版社,1995.Cai Chunyuan.Mechanical parts design manual[M].Beijing:Metallurgical Industry Press,1995.
[19]殷有泉,李平恩.非均匀载荷下套管强度的计算[J].石油学报,2007,28(6):138-146.Yin Youquan,Li Ping’en.Computation of casing strength under non-uniform load[J].Acta Petrolei Sinica,2007,28(6):138-146.
[20]廖华林,管志川,马广军,等.深井超深井内壁磨损套管剩余强度计算[J].工程力学,2010,27(2):250-255.Liao Hualin,Guan Zhichuan,Ma Guangjun,et al.Remaining strength calculation of internal wall worn casing in deep and ultra-deep wells[J].Engineering Mechanics,2010,27(2):250-255.
[21]Adams A J,Parfitt S H L,Reeves T B,et al.Casing system risk analysis using structural reliability[R].SPE25693,1993.
[22]Galambos T V,Ravindra M K.Properties of steel for use in LRFD[J].Journal of the Structural Engineering Division,ASCE,1978,104(9):1459-1468.
[23]中华人民共和国住房和城乡建设部.GB50009-2012建筑结构荷载规范[S].北京:中国建筑工业出版社,2012.Ministry of Housing and Urban-Rural Development of the People’s Republic of China.GB50009-2012 Load code for the design of building structures[S].Beijing:China Architecture&Building Press,2012.