海上高温高压井套管应力分析
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摘要
套管损坏是影响海上高温高压井开发效益的重要原因之一。在准确求解井筒温度场的基础上,考虑地层非均匀地应力、地层高压与热应力的影响,计算套管-水泥环-地层系统耦合热应力状态,分析水泥环、套管性能参数等对套管损坏的影响。结果表明,随着离套管中心径向距离的增加,Mises应力逐渐降低、径向应力呈现"增-减"变化趋势、周向应力呈现"跳跃式"变化,综合确定套管内壁处套管损坏风险最高;考虑高温高压时,套管Mises应力更高,套损风险增大;随着圆周角的变化,Mises应力、剪应力最大值出现于圆周角45°、周向应力最大值出现于圆周角0°;随套管、水泥环弹性模量与热膨胀系数的增大,套管Mises应力逐渐增大。研究成果对于海上高温高压井的套管损坏分析具有一定的指导意义。
Casing failure is one of the important factors affecting the development efficiency of offshore high temperature and high pressure(HTHP) wells. So far, the influence of HTHP on casing stress has not been studied deeply. In this paper, wellbore temperaturefield was calculated accurately. Then, the coupling thermal stress state of casing-cement sheath-formation system was calculated in consideration of the influence of non-uniform in-situ stress, high formation pressure and thermal stress. Finally, the effects of the performance parameters of cement sheath and casing on the casing failure were analyzed. It is indicated that with the increase of radial distance from the casing center, the Mises stress decreases gradually, the radial stress increases firstly and then decreases, and the circumferential stress presents a "skip" change. It is comprehensively determined that the risk of casing failure is the highest at the inner wall. If HPHT is taken into account, the Mises stress of casing and the risk of casing failure will increase. With the change of circumference angle, the maximum values of Mises stress and shear stress appear at the circumference angle of 45°, and the maximum circumferential stress appears at the circumference angle of 0°. With the increase of the elastic modulus and thermal expansion coefficient of casing and cement sheath, the Mises stress of casing increases gradually. The research results are of some guiding significance to the analysis on the casing failure of offshore HPHT wells.
Casing failure is one of the important factors affecting the development efficiency of offshore high temperature and high pressure(HTHP) wells. So far, the influence of HTHP on casing stress has not been studied deeply. In this paper, wellbore temperaturefield was calculated accurately. Then, the coupling thermal stress state of casing-cement sheath-formation system was calculated in consideration of the influence of non-uniform in-situ stress, high formation pressure and thermal stress. Finally, the effects of the performance parameters of cement sheath and casing on the casing failure were analyzed. It is indicated that with the increase of radial distance from the casing center, the Mises stress decreases gradually, the radial stress increases firstly and then decreases, and the circumferential stress presents a "skip" change. It is comprehensively determined that the risk of casing failure is the highest at the inner wall. If HPHT is taken into account, the Mises stress of casing and the risk of casing failure will increase. With the change of circumference angle, the maximum values of Mises stress and shear stress appear at the circumference angle of 45°, and the maximum circumferential stress appears at the circumference angle of 0°. With the increase of the elastic modulus and thermal expansion coefficient of casing and cement sheath, the Mises stress of casing increases gradually. The research results are of some guiding significance to the analysis on the casing failure of offshore HPHT wells.
引文
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[14]范明涛,柳贡慧,李军,等.页岩气井温压耦合下固井质量对套管应力的影响[J].石油机械,2016,44(8):1-5.
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[2]陈勇,练章华,陈若铭,等.基于残余应力的热采井套管安全评价分析[J].石油矿场机械,2009,38(4):16-19.
[3]余雷,薄岷.辽河油田热采井套损防治新技术[J].石油勘探与开发,2005,32(1):116-118.
[4]张万才,马振生,郭立君,等.热采井套管损坏机理及防治技术--以单家寺油田为例[J].油气地质与采收率,2005,12(2):74-76.
[5]WU J,GONZALEZ M E,HONSN N.Steam injection casing design[J].SPE 93833,2005:1-12.
[6]BOUR D.Cyclic steam well design-A new approach to solve an old problem of cement sheath failure in cyclic steam wells[J].SPE 93868,2005:1-12.
[7]王耀锋,李军强,杨小辉.套管-水泥环-地层系统应力分布规律研究[J].石油钻探技术,2008,36(5):7-11.
[8]邓金根,王康平,黄荣樽,等.油井套管、水泥环组合体抗非均匀围岩外载的强度特性[J].岩石力学与工程学报,1994,13(2):160-167.
[9]练章华,罗泽利,于浩,等.砂泥岩夹层套管损坏的有限元分析及防控措施[J].石油钻采工艺,2016,38(6):887-892.
[10]席岩,柳贡慧,李军,等.力-热耦合作用下套管应力瞬态变化研究[J].石油机械,2017,45(6):8-12.
[11]李静,林承焰,杨少春,等.套管-水泥环-地层耦合系统热应力理论解[J].中国石油大学学报(自然科学版),2009,33(2):63-69.
[12]陈朝伟,殷有泉.水泥环对套管载荷影响的理论研究[J].石油学报,2007,28(3):141-144.
[13]练章华,罗泽利,步宏光,等.水泥环环状缺失套损机理及防控措施[J].石油钻采工艺,2017,39(4):435-441.
[14]范明涛,柳贡慧,李军,等.页岩气井温压耦合下固井质量对套管应力的影响[J].石油机械,2016,44(8):1-5.
[15]LI Y,LIU S,WANG Z,et al.Analysis of cement sheath coupling effects of temperature and pressure in non-uniform in-situ stress field[R].SPE 131878,2010.
[16]VAZQUEZ G,BLANCO A M,Colina A M.A methodology to evaluate the gas migration in cement slurries[C].SPE Latin American and Caribbean Petroleum Engineering Conference,Society of Petroleum Engineers,Rio de Janeiro,Brazil,2005.
[17]KRUSCHE K,JOHNSON C R,BRAUD N Y,et al.Application of engineered cementingsolution to solve long-term cement integrity issues in tunisia[C].SPEAnnual Technical Conference and Exhibition,Society of Petroleum Engineers,San,Antonio,Texas,2006.
[18]THIERCELIN M,DARGAUD B,BARET J,et al.Cement design based on cement mechanical response[C].SPEannual technical conference and exhibition,Society of Petroleum Engineers,San,Antonio,Texas,1997.
[19]THIERCELIN M,BAUMGARTE C,GUILLOT D.A soil mechanics approach to predict cement sheath behavior[C].SPE/ISRM Rock Mechanics in Petroleum Engineering,Society of Petroleum Engineers,trondheim norway,1998:329-337.