深水油气田钻井安全密度窗口计算方法
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摘要
近年来深水油气勘探发展迅速,与陆上及浅海区域的钻井相比,深水上覆岩层压力较低,容易发生漏失。另外,深水浅层泥页岩也容易发生水化坍塌。因此,深水钻井中要求提供更精确的安全密度窗口,以防止发生复杂事故。通过借鉴陆上与浅海地区钻井中的井壁稳定性分析方法,结合深水钻井自身特点,得出了深水钻井安全密度窗口计算方法,其中上覆岩层压力利用密度积分方法计算,孔隙压力可以利用测井数据根据Eaton法进行计算。针对深水浅部地层的特殊性,建立了塑性区半径评价法用于浅部地层坍塌压力计算,并且认为深水钻井中漏失压力等于水平最小主应力,钻井中将漏失压力作为允许使用钻井液密度的上限。根据上述计算方法可以得出深水钻井的安全密度窗口,为钻井工程提供参考。
Oil and gas exploration in deepwater areas has developed rapidly for recent years.Compared with drilling on land or in shallow water,the overburden pressure was lower in deepwater,which would cause lost circulation easily.In addition,Shale in the shallow formation of deepwater area was easy to be collapse because of hydration.Therefore,more accurate safety density window was required to prevent the occurrence of complex problem in deepwater drilling.By using the analycal method of borehole stability on land and in shallow water,and in combination with the characteristics of deepwater drilling,a calculation method of drilling safety density window was obtained.Overburden pressure can be calculated by using density integral method,and pore pressure can be calculated by Eaton method with logging data.According to particularity of shallow formation in deepwater,plastic area radius estimated method is established to calculate collapse pressure.Furthermore,the upper limitation of allowable drilling fluid density in drilling is leakage pressure that is equal to minimum horizontal principle stress.The safety density window of deepwater drilling can be calculated by above method,which can provide reference for drilling engineering.
Oil and gas exploration in deepwater areas has developed rapidly for recent years.Compared with drilling on land or in shallow water,the overburden pressure was lower in deepwater,which would cause lost circulation easily.In addition,Shale in the shallow formation of deepwater area was easy to be collapse because of hydration.Therefore,more accurate safety density window was required to prevent the occurrence of complex problem in deepwater drilling.By using the analycal method of borehole stability on land and in shallow water,and in combination with the characteristics of deepwater drilling,a calculation method of drilling safety density window was obtained.Overburden pressure can be calculated by using density integral method,and pore pressure can be calculated by Eaton method with logging data.According to particularity of shallow formation in deepwater,plastic area radius estimated method is established to calculate collapse pressure.Furthermore,the upper limitation of allowable drilling fluid density in drilling is leakage pressure that is equal to minimum horizontal principle stress.The safety density window of deepwater drilling can be calculated by above method,which can provide reference for drilling engineering.
引文
[1]杨进,曹式敬.深水石油钻井技术现状及发展趋势[J].石油钻采工艺,2008,30(2):10～13.
[2]Santos H,Fontoura S,Gupta A,et al.Laboratory tests for wellbore stability in deepwater,Brazil[J].SPE 38977,1997.
[3]Moos D.Wellbore Stability in deep water-handling geomechanical uncertainty[A].The AADE 2001National Drilling Conference heldat the Omni,Houston,Texas,USA,Mar 27-29,2001.
[4]Ritter D G,Grollimund B.Wellbore stability in the deepwater Bijupira&Salema Fields,Offshore Brazil-a probabilistic approach[A].The 2003offshore technology conference held in Houston,Texas,USA,May 5-8,2003.OTC 15205.
[5]樊洪海.测井资料检测地层孔隙压力传统方法讨论[J].石油勘探与开发,2003,30(4):72～73.
[6]张荣忠,郭良川,徐辉.孔隙压力地震预测技术综述[J].勘探地球物理进展,2005,28(2):90～96.
[7]Liaw A L.Theory and application of integrated pore pressure prediction in deepwater exploration[A].The International PetroleumTechnology Conference held in Kuala Lumpur,Malaysia,Dec 3-5,2008.IPTC 12072.
[8]Eaton B A.The equation for geopressure prediction from well logs[J].SPE 5544,1975.
[9]刘岩生,苏义脑.探井地层孔隙压力计算[J].石油钻采工艺,2000,22(5):6～9.
[10]Bowers G L.Pore pressure estimation from velocity data:accounting for overpressure mechanisms besides undercompaction[J].SPEDrilling&Completion,1995,10(2):89～95.
[11]楼一珊,金业权.岩石力学与石油工程[M].北京:石油工业出版社,2006.
[12]Risnes R,Bratli R K,Horsurd P.Sand stresses around a well[J].SPEJ,1982:883～898.
[13]朱亮,张春阳,楼一珊,等.两种漏失压力计算模型的比较分析[J].天然气工业,2008,28(12):60～61,67.
[14]Aadnoy B S.Geomechanical analysis for deep-water drilling[J].SPE39339,1998.
[2]Santos H,Fontoura S,Gupta A,et al.Laboratory tests for wellbore stability in deepwater,Brazil[J].SPE 38977,1997.
[3]Moos D.Wellbore Stability in deep water-handling geomechanical uncertainty[A].The AADE 2001National Drilling Conference heldat the Omni,Houston,Texas,USA,Mar 27-29,2001.
[4]Ritter D G,Grollimund B.Wellbore stability in the deepwater Bijupira&Salema Fields,Offshore Brazil-a probabilistic approach[A].The 2003offshore technology conference held in Houston,Texas,USA,May 5-8,2003.OTC 15205.
[5]樊洪海.测井资料检测地层孔隙压力传统方法讨论[J].石油勘探与开发,2003,30(4):72～73.
[6]张荣忠,郭良川,徐辉.孔隙压力地震预测技术综述[J].勘探地球物理进展,2005,28(2):90～96.
[7]Liaw A L.Theory and application of integrated pore pressure prediction in deepwater exploration[A].The International PetroleumTechnology Conference held in Kuala Lumpur,Malaysia,Dec 3-5,2008.IPTC 12072.
[8]Eaton B A.The equation for geopressure prediction from well logs[J].SPE 5544,1975.
[9]刘岩生,苏义脑.探井地层孔隙压力计算[J].石油钻采工艺,2000,22(5):6～9.
[10]Bowers G L.Pore pressure estimation from velocity data:accounting for overpressure mechanisms besides undercompaction[J].SPEDrilling&Completion,1995,10(2):89～95.
[11]楼一珊,金业权.岩石力学与石油工程[M].北京:石油工业出版社,2006.
[12]Risnes R,Bratli R K,Horsurd P.Sand stresses around a well[J].SPEJ,1982:883～898.
[13]朱亮,张春阳,楼一珊,等.两种漏失压力计算模型的比较分析[J].天然气工业,2008,28(12):60～61,67.
[14]Aadnoy B S.Geomechanical analysis for deep-water drilling[J].SPE39339,1998.
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