气井生产过程中碳钢管柱CO_2腐蚀规律
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摘要
掌握气井稳态生产过程中CO_2对碳钢管柱沿井深方向的腐蚀规律才能更好地确定油气田开发和实施方案,预防和降低管柱腐蚀失效事故。根据质量守恒、动量守恒、能量守恒以及非理想气体状态方程建立了地面稳态生产条件下管柱内热流耦合计算模型,并与实测结果进行了对比研究。以Norsok模型为基础,根据实际生产用管材等建立了相应的修正表达式,并进行了实例验证。研究了CO_2摩尔分数、井筒总体传热系数,管柱内半径和日产量对管柱腐蚀速率的影响。研究表明,建立的热流耦合模型和腐蚀预测模型计算精度满足工程需要;地面日产量越大,井深方向管柱内天然气密度、速度、温度越高,而压力越低;增加CO_2摩尔分数和地面日产气量、降低井筒总体传热系数和管柱内径均可引起管柱最大腐蚀速率出现的位置向井口方向移动,并且日产气量和井筒总体传热系数的影响更为明显;沿井深方向上,管柱腐蚀速率变化分为4个阶段,且不同影响参数变化时,腐蚀速率的影响规律不尽相同。
The CO_2 corrosion law for carbon steel tubing string along the wellbore depth direction in the steady-state production process of gas well is studied to better determine the development and implementation scheme of oil and gas field,prevent and reduce tubing string corrosion failure accidents.In this study,a thermal-flow coupling model in tubing string during steady production process is established on the bases of the mass conservation,momentum conservation,energy conservation and non-ideal gas state equations,and the results from the model are compared with the measured data.A corresponding amendment expression is built based on the Norsok model,actual tubing string materials and so on,and an example is provided to prove its validity.The effects of CO_2 mole fraction,total heat transfer coefficient of wellbore,tubing string inner diameter and daily gas production rate on the corrosion rate of tubing string are studied,and the results show that the calculation precision of coupling model and corrosion prediction model is able to satisfy the engineering requirement.The larger the daily gas production on the ground is,the higher the density,velocity and temperature of natural gas in tubing string along the well depth direction will be,but the lower the pressure will be.Increasing the mole fraction of CO_2 and surface daily gas production as well as decreasing the total heat transfer coefficient of wellbore and inner diameter of tubing string can both lead to the occurrence position of maximum corrosion rate in tubing string moving towards wellhead,and the effects of daily gas production and total heat transfer coefficient of wellbore are more obvious.The variation of tubing string corrosion rate can be divided into four stages along the wellbore depth,and the influence law of corrosion rate varies with different impact parameters.
The CO_2 corrosion law for carbon steel tubing string along the wellbore depth direction in the steady-state production process of gas well is studied to better determine the development and implementation scheme of oil and gas field,prevent and reduce tubing string corrosion failure accidents.In this study,a thermal-flow coupling model in tubing string during steady production process is established on the bases of the mass conservation,momentum conservation,energy conservation and non-ideal gas state equations,and the results from the model are compared with the measured data.A corresponding amendment expression is built based on the Norsok model,actual tubing string materials and so on,and an example is provided to prove its validity.The effects of CO_2 mole fraction,total heat transfer coefficient of wellbore,tubing string inner diameter and daily gas production rate on the corrosion rate of tubing string are studied,and the results show that the calculation precision of coupling model and corrosion prediction model is able to satisfy the engineering requirement.The larger the daily gas production on the ground is,the higher the density,velocity and temperature of natural gas in tubing string along the well depth direction will be,but the lower the pressure will be.Increasing the mole fraction of CO_2 and surface daily gas production as well as decreasing the total heat transfer coefficient of wellbore and inner diameter of tubing string can both lead to the occurrence position of maximum corrosion rate in tubing string moving towards wellhead,and the effects of daily gas production and total heat transfer coefficient of wellbore are more obvious.The variation of tubing string corrosion rate can be divided into four stages along the wellbore depth,and the influence law of corrosion rate varies with different impact parameters.
引文
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[15]ZHOU Desheng,YUAN Hong.A new model for predicting gas-well liquid loading[J].SPE Production&Operations,2010,25(2):172-181.
[16]马德胜,王伯军,吴淑红.油气生产过程中CO2腐蚀预测研究[J].西南石油大学学报:自然科学版,2010,32(3):137-140.MA Desheng,WANG Bojun,WU Shuhong.Research on prediction of carbon dioxide corrosion in hydrocarbon production process[J].Journal of Southwest Petroleum University:Science&Technology Edition,2010,32(3):137-140.
[17]冯叔初,郭揆常,王学敏.油气集输[M].东营:石油大学出版社,1988.FENG Shuchu,GUO Kuichang,WANG Xuemin.Oil&gas gathering and transportation[M].Dongying:Petroleum University Press,1988.
[18]ЧерникинA B.管道水力摩阻的计算[J].油气储运,1999,18(2):26-28.ЧерникинA B.Generalized equation to calculate the coefficient of hydrualic friction of pipeline[J].Oil&Gas Storage and Transportation,1999,18(2):26-28.
[19]关欣.CO2对天然气井管柱腐蚀模拟研究及应用[D].成都:西南石油大学,2014.GUAN Xin.Corrosion simulation and application of CO2 for string in natural gas well[D].Chengdu:Southwest Petroleum U-niversity,2014.
[20]AZIZI N,BEHBAHANI D R,ISAZADEH D M A.An efficient correlation for calculating compressibility factor of natural gases[J].Journal of Natural Gas Chemistry,2010,19(6):642-645.
[21]熊治富,邓金花,陈丹.川东北地区天然气偏差系数计算方法评价[J].西南石油大学学报:自然科学版,2015,37(4):60-66.XIONG Zhifu,DENG Jinhua,CHEN Dan.The comprehensive evaluation of the deviation factor calculation of natural gas in Northeast Sichuan[J].Journal of Southwest Petroleum University:Science&Technology Edition,2015,37(4):60-66.
[22]HALVORSEN A M,SONTVEDT T.CO2corrosion model for carbon steel including wall shear stress model for multiphase flow and limits for production rate to avoid mesa attack[C]∥CORROSION99,25-30 April 1999,San Antonio,Texas.San Antonio,Texas:NACE International,1999.
[23]杨涛,杨桦,王凤江,等.含CO2气井防腐工艺技术[J].天然气工业,2007,27(11):116-118.YANG Tao,YANG Hua,WANG Fengjiang,et al.Anti-corrosion technology in gas wells with CO2[J].Natural Gas Industry,2007,27(11):116-118.
[24]CROLET J L,BONIS M R.Algorithm of the protectiveness of corrosion layers 1-Protectiveness mechanisms and CO2corrosion prediction[C]∥CORROSION2010,14-18 March 2010,San Antonio,Texas.San Antonio,Texas:NACE International,2010.
[2]朱红钧,唐有波,李珍明,等.气井A环空压力恢复与泄压实验[J].石油学报,2016,37(9):1171-1178.ZHU Hongjun,TANG Youbo,LI Zhenming,et al.Experiment on pressure recovery and relief in the A annulus space of gas well[J].Acta Petrolei Sinica,2016,37(9):1171-1178.
[3]HASAN A R,KABIR C S.Wellbore heat-transfer modeling and applications[J].Journal of Petroleum Science and Engineering,2012,86-87:127-136.
[4]郭春秋,李颖川.气井压力温度预测综合数值模拟[J].石油学报,2001,22(3):100-104.GUO Chunqiu,LI Yingchuan.Comprehensive numerical simulation of pressure and temperature prediction in gas well[J].Acta Petrolei Sinica,2001,22(3):100-104.
[5]陈林,余忠仁.气井非稳态流井筒温度压力模型的建立和应用[J].天然气工业,2017,37(3):70-76.CHEN Lin,YU Zhongren.Construction and application of a wellbore temperature and pressure model for unsteady flow in gas wells[J].Natural Gas Industry,2017,37(3):70-76.
[6]陈会娟,李明忠,狄勤丰,等.多点注汽水平井井筒出流规律数值模拟[J].石油学报,2017,38(6):696-704.CHEN Huijuan,LI Mingzhong,DI Qinfeng,et al.Numerical simulation of the outflow performance for horizontal wells with multiple steam injection valves[J].Acta Petrolei Sinica,2017,38(6):696-704.
[7]NYBORG R.CO2corrosion models for oil and gas production systems[C]∥CORROSION2010,14-18 March 2010,San Antonio,Texas.San Antonio,Texas:NACE International,2010.
[8]Standards Norway.CO2corrosion rate calculation model:Norsok Standard No.M506[S].Standards Norway,2005.
[9]王献昉,陈长风,白真权,等.CO2腐蚀速率半经验预测模型研究[J].腐蚀与防护,2009,30(2):90-94.WANG Xianfang,CHEN Changfeng,BAI Zhenquan,et al.Semiempirical model for prediction of CO2corrosion rate[J].Corrosion&Protection,2009,30(2):90-94.
[10]CHENG Yuanpeng,LI Zili,LIU Qianqian.Research on CO2corrosion rate prediction of gathering pipelines considering the effect of oil[J].Applied Mechanics and Materials,2015,737:788-793.
[11]NORDSVEEN M,NEIC′S,NYBORG R,et al.A mechanistic model for carbon dioxide corrosion of mild steel in the presence of protective iron carbonate films-part 1:theory and verification[J].Corrosion,2003,59(6):443-456.
[12]NEIC′S,NORDSVEEN M,NYBORG R,et al.A mechanistic model for carbon dioxide corrosion of mild steel in thepresence of protective iron carbonate films-part 2:a numerical experiment[J].Corrosion,2003,59(6):489-497.
[13]GARBER J D,PATIL V B,YAP K M.CO2,H2S and bacteria pitting corrosion model[C]∥CORROSION2011,13-17 March2011,Houston,Texas.Houston,Texas:NACE International,2011.
[14]张智,刘志伟,谢玉洪,等.井筒载荷-腐蚀耦合作用对碳钢套管服役寿命的影响[J].石油学报,2017,38(3):342-347.ZHANG Zhi,LIU Zhiwei,XIE Yuhong,et al.Influence of shaft load-corrosion coupling on the service life of carbon steel casing pipe[J].Acta Petrolei Sinica,2017,38(3):342-347.
[15]ZHOU Desheng,YUAN Hong.A new model for predicting gas-well liquid loading[J].SPE Production&Operations,2010,25(2):172-181.
[16]马德胜,王伯军,吴淑红.油气生产过程中CO2腐蚀预测研究[J].西南石油大学学报:自然科学版,2010,32(3):137-140.MA Desheng,WANG Bojun,WU Shuhong.Research on prediction of carbon dioxide corrosion in hydrocarbon production process[J].Journal of Southwest Petroleum University:Science&Technology Edition,2010,32(3):137-140.
[17]冯叔初,郭揆常,王学敏.油气集输[M].东营:石油大学出版社,1988.FENG Shuchu,GUO Kuichang,WANG Xuemin.Oil&gas gathering and transportation[M].Dongying:Petroleum University Press,1988.
[18]ЧерникинA B.管道水力摩阻的计算[J].油气储运,1999,18(2):26-28.ЧерникинA B.Generalized equation to calculate the coefficient of hydrualic friction of pipeline[J].Oil&Gas Storage and Transportation,1999,18(2):26-28.
[19]关欣.CO2对天然气井管柱腐蚀模拟研究及应用[D].成都:西南石油大学,2014.GUAN Xin.Corrosion simulation and application of CO2 for string in natural gas well[D].Chengdu:Southwest Petroleum U-niversity,2014.
[20]AZIZI N,BEHBAHANI D R,ISAZADEH D M A.An efficient correlation for calculating compressibility factor of natural gases[J].Journal of Natural Gas Chemistry,2010,19(6):642-645.
[21]熊治富,邓金花,陈丹.川东北地区天然气偏差系数计算方法评价[J].西南石油大学学报:自然科学版,2015,37(4):60-66.XIONG Zhifu,DENG Jinhua,CHEN Dan.The comprehensive evaluation of the deviation factor calculation of natural gas in Northeast Sichuan[J].Journal of Southwest Petroleum University:Science&Technology Edition,2015,37(4):60-66.
[22]HALVORSEN A M,SONTVEDT T.CO2corrosion model for carbon steel including wall shear stress model for multiphase flow and limits for production rate to avoid mesa attack[C]∥CORROSION99,25-30 April 1999,San Antonio,Texas.San Antonio,Texas:NACE International,1999.
[23]杨涛,杨桦,王凤江,等.含CO2气井防腐工艺技术[J].天然气工业,2007,27(11):116-118.YANG Tao,YANG Hua,WANG Fengjiang,et al.Anti-corrosion technology in gas wells with CO2[J].Natural Gas Industry,2007,27(11):116-118.
[24]CROLET J L,BONIS M R.Algorithm of the protectiveness of corrosion layers 1-Protectiveness mechanisms and CO2corrosion prediction[C]∥CORROSION2010,14-18 March 2010,San Antonio,Texas.San Antonio,Texas:NACE International,2010.