浮力作用对大斜度井套管居中度的影响
|
摘要
准确了解套管内外密度差所产生的浮力对套管居中度的影响对于大斜度井合理安放扶正器,降低套管下入风险具有重要的意义。通过对扶正器受力分析模型进行修正,建立了套管内外密度差对套管居中度的影响图版,同时考虑顶替过程中套管内外密度差随时间变化情况,形成埕海油田大斜度井套管扶正器安放方法。计算结果表明,埕海地区扶正器安放间距分别为30 m、20 m、15 m时,通过浮力作用使套管居中度最大可增加36.4%、19.6%、12.2%,井斜角越大、套管内外密度差越大,居中度变化值越大。扶正器安放间距为10 m时,浮力作用减弱,居中度变化值最大仅为6.2%。研究结果表明,扶正器安放间距、井斜角的正弦值、套管内外密度差与浮力作用下的居中度变化量呈三次多项式的非线性正相关。ZH29-30井实践表明,考虑浮力作用的套管居中度设计方法,可以有效提高固井顶替效率,保证套管安全下入。
In order to install centralizers in high angle deviated wells rationally and decrease the risk of casing running, it is significant to figure out accurately the effect of buoyance generated by the difference of density inside and outside the casing on the casing central degree. In this paper, the model for analyzing the forces on centralizers was modified and a chart describing the influence of density difference between inside and outside the casing on the casing central degree was established. And the change of density difference between inside and outside the casing over the time in the process of displacement was also taken into consideration. Thus, the centralizer installation method for high angle deviated wells in Chenghai Oilfield was developed. Calculation results show that the maximum increment of casing central degree due to buoyance is 36.4%, 19.6% and 12.2% when the centralizer installation spacing in the area of Chenghai is 30 m, 20 m and 15 m. The higher the hole deviation angle is and the higher the density difference between inside and outside the casing is, the larger the variation of central degree is. When the centralizer installation spacing is 10 m, buoyance gets weak and maximum variation of central degree is only 6.2%. It is in nonlinear positive correlation of cubic polynomial between centralizer installation spacing, sine of hole deviation angle, density difference between inside and outside the casing and central degree variation under the effect of buoyance. It is shown from the practice in Well ZH29-30 that the casing central degree design method which takes the buoyance into account can improve the displacement efficiency of cementing and ensure the safe running of casing.
In order to install centralizers in high angle deviated wells rationally and decrease the risk of casing running, it is significant to figure out accurately the effect of buoyance generated by the difference of density inside and outside the casing on the casing central degree. In this paper, the model for analyzing the forces on centralizers was modified and a chart describing the influence of density difference between inside and outside the casing on the casing central degree was established. And the change of density difference between inside and outside the casing over the time in the process of displacement was also taken into consideration. Thus, the centralizer installation method for high angle deviated wells in Chenghai Oilfield was developed. Calculation results show that the maximum increment of casing central degree due to buoyance is 36.4%, 19.6% and 12.2% when the centralizer installation spacing in the area of Chenghai is 30 m, 20 m and 15 m. The higher the hole deviation angle is and the higher the density difference between inside and outside the casing is, the larger the variation of central degree is. When the centralizer installation spacing is 10 m, buoyance gets weak and maximum variation of central degree is only 6.2%. It is in nonlinear positive correlation of cubic polynomial between centralizer installation spacing, sine of hole deviation angle, density difference between inside and outside the casing and central degree variation under the effect of buoyance. It is shown from the practice in Well ZH29-30 that the casing central degree design method which takes the buoyance into account can improve the displacement efficiency of cementing and ensure the safe running of casing.
引文
[1]丁保刚,李国庆,姜文勇,李子丰.套管居中设计和校核[J].石油钻探技术,2009,37(1):58-61.DING Baogang,LI Guoqing,JIANG Wenyong,LIZifeng.Casing centralization design and verfication[J].Petroleum Drilling Techniques,2009,37(1):58-61.
[2]谭树人.大斜度井、水平井套管扶正器最佳间距计算[J].中国海上油气(工程),1993,5(4):40-44.TAN Shuren.The calculation of centralizer spacing in high angle wells,horizontal well[J].China Offshore Oil and Gas(Engineering),1993,5(4):40-44.
[3]孙铭新,张大千,步玉环,孙旺.大位移井套管轴向力对套管挠度的影响[J].石油矿场机械,2014,43(1):7-10.SUN Mingxin,ZHANG Daqian,BU Yuhuan,SUN Wang.Effect of axial force on casing deflection in extendedreach well[J].Oil Field Equipment,2014,43(1):7-10.
[4]王九龙,吴朗.套管柱扶正优化设计与软件实现[J].西部探矿工程,2014(4):64-66.WANG Jiulong,WU Lang.The casing centralizer optimization design and software implementation[J].West-china Exploration Engineering,2014(4):64-66.
[5]国家发展与改革委员会.SY/T 5724-2008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/T 5724-2008 Design for casing string structure and strength[S].Beijing:Petroleum Industry Press,2008.
[6]魏涛.油气井固井质量测井评价[M].北京:石油工业出版社,2010.WEI Tao.Evaluation of oil and gas well cementing quality[M].Beijing:Petroleum Industry Press,2010.
[2]谭树人.大斜度井、水平井套管扶正器最佳间距计算[J].中国海上油气(工程),1993,5(4):40-44.TAN Shuren.The calculation of centralizer spacing in high angle wells,horizontal well[J].China Offshore Oil and Gas(Engineering),1993,5(4):40-44.
[3]孙铭新,张大千,步玉环,孙旺.大位移井套管轴向力对套管挠度的影响[J].石油矿场机械,2014,43(1):7-10.SUN Mingxin,ZHANG Daqian,BU Yuhuan,SUN Wang.Effect of axial force on casing deflection in extendedreach well[J].Oil Field Equipment,2014,43(1):7-10.
[4]王九龙,吴朗.套管柱扶正优化设计与软件实现[J].西部探矿工程,2014(4):64-66.WANG Jiulong,WU Lang.The casing centralizer optimization design and software implementation[J].West-china Exploration Engineering,2014(4):64-66.
[5]国家发展与改革委员会.SY/T 5724-2008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/T 5724-2008 Design for casing string structure and strength[S].Beijing:Petroleum Industry Press,2008.
[6]魏涛.油气井固井质量测井评价[M].北京:石油工业出版社,2010.WEI Tao.Evaluation of oil and gas well cementing quality[M].Beijing:Petroleum Industry Press,2010.