一种准确预测钻井液安全密度窗口的新方法
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摘要
准确预测钻井液安全密度窗口是井身结构设计和钻井液密度合理选择的前提。常用的钻井液安全密度窗口预测方法是基于Mohr-Coulomb破坏准则和拉伸破坏准则而建立的。但是,由于Mohr-Coulomb破坏准则未考虑中间主应力的影响,预测的钻井液密度偏高,不利于钻井提速和储层保护。为此,引入Mogi-Coulomb破坏准则,建立了3种地应力状态下预测直井钻井液安全密度窗口的新方法,克服了传统方法计算坍塌压力过于保守和计算破裂压力未考虑剪性破裂的不足。将其应用于川西地区H1井砂泥岩地层的钻井液安全密度窗口计算中,结果表明,新方法的预测结果较传统方法的计算结果更符合实际情况,且精度高、实用性强,对解决钻井中的井壁失稳问题有重要的指导意义。
Accurately predicting the safe window of drilling fluid density is a prerequisite for well structure design and reasonable choice of drilling fluid density. The commonly used prediction method is based on Mohr-Coulomb failure criterion and tensile failure criterion. However, the Mohr-Coulomb failure criterion does not consider the role of intermediate principal stress, which makes the predicted drilling fluid density too high, and then greatly affects drilling speed and reservoir protection. Therefore, the MogiCoulomb failure criterion is introduced and a new method to predict the vertical safe window of drilling fluid density is established under three stress states. This method overcomes the shortcomings of the traditional model that calculation of collapse pressure is too conservative and calculation of fracture pressure does not take into account shear failure. It is used to calculate safe window of drilling fluid density of the sandstone and mudstone formation for H1 Well in western Sichuan. It is found that the prediction is more practical and accurate than traditional method. The results show that the result predicted by the new method is more realistic than those calculated by traditional method and has high precision and practicability. These results have important guiding significance to solve the instability of borehole during drilling.
Accurately predicting the safe window of drilling fluid density is a prerequisite for well structure design and reasonable choice of drilling fluid density. The commonly used prediction method is based on Mohr-Coulomb failure criterion and tensile failure criterion. However, the Mohr-Coulomb failure criterion does not consider the role of intermediate principal stress, which makes the predicted drilling fluid density too high, and then greatly affects drilling speed and reservoir protection. Therefore, the MogiCoulomb failure criterion is introduced and a new method to predict the vertical safe window of drilling fluid density is established under three stress states. This method overcomes the shortcomings of the traditional model that calculation of collapse pressure is too conservative and calculation of fracture pressure does not take into account shear failure. It is used to calculate safe window of drilling fluid density of the sandstone and mudstone formation for H1 Well in western Sichuan. It is found that the prediction is more practical and accurate than traditional method. The results show that the result predicted by the new method is more realistic than those calculated by traditional method and has high precision and practicability. These results have important guiding significance to solve the instability of borehole during drilling.
引文
[1]邓金根,张洪生.钻井工程中井壁失稳的力学机理[M].北京:石油工业出版社,1998:30-33.
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[3]贾利春,黄晓嘉,郭正温.井壁稳定性研究中考虑中间主应力强度准则的对比分析[J].断块油气田,2017,24(1):105-111.
[4] VERNIK L, ZOBACK M D. Estimation of maximum horizontal principal stress magnitude from stress-induced well bore breakouts in the Cajon Pass scientific research borehole[J]. Journal of Geophysical Research:Solid Earth,1992,97(B4):5109-5119.
[5] AL-AJMI A M,ZIMMERMAN R W. Relation between the Mogi and the Coulomb failure criteria[J]. International Journal of Rock Mechanics and Mining Sciences,2005,42(3):431-439.
[6] AL-AJMI A M,ZIMMERMAN R W. A new well path optimization model for increased mechanical borehole stability[J]. Journal of Petroleum Science and Engineering,2009,69(1/2):53-62.
[7]金衍,陈勉,柳贡慧,等.大位移井的井壁稳定力学分析[J].地质力学学报,1999,5(1):4-11.
[8]金衍,陈勉,陈治喜,等.弱面地层的直井井壁稳定力学模型[J].钻采工艺,1999,22(3):13-14.
[9]阳友奎,肖长富.不同地应力状态下水力压裂的破裂模式[J].重庆大学学报(自然科学版),1993,16(3):30-35.
[10] LIU J Z,CHAO X L,LI Z Q. Shear fracturing during the process of hydrofractures[J]. Journal of Seismological Research,1984,7(2):253-262.
[11]刘建中,李自强.对水压致裂应力测量理论的实验与分析[J].岩石力学与工程学报,1986,5(3):267-276.
[12]闫传梁,谢玉洪,邓金根,等.安全钻井液密度上限的确定方法[J].天然气工业,2013,33(6):80-85.
[13]朴玉芝,赵素红.利用测井资料确定合理钻井液密度方法的研究[J].钻采工艺,1998,21(5):20-22.
[14]程远方,徐同台.安全泥浆密度窗口的确立及应用[J].石油钻探技术,1999,27(3):16-18.
[15]黄荣樽.水力压裂裂缝的起裂和扩展[J].石油勘探与开发,1981,8(5):62-74.
[2]胜亚楠,管志川,许玉强,等.井壁稳定问题的不确定性分析方法探讨[J].断块油气田,2017,24(6):847-850.
[3]贾利春,黄晓嘉,郭正温.井壁稳定性研究中考虑中间主应力强度准则的对比分析[J].断块油气田,2017,24(1):105-111.
[4] VERNIK L, ZOBACK M D. Estimation of maximum horizontal principal stress magnitude from stress-induced well bore breakouts in the Cajon Pass scientific research borehole[J]. Journal of Geophysical Research:Solid Earth,1992,97(B4):5109-5119.
[5] AL-AJMI A M,ZIMMERMAN R W. Relation between the Mogi and the Coulomb failure criteria[J]. International Journal of Rock Mechanics and Mining Sciences,2005,42(3):431-439.
[6] AL-AJMI A M,ZIMMERMAN R W. A new well path optimization model for increased mechanical borehole stability[J]. Journal of Petroleum Science and Engineering,2009,69(1/2):53-62.
[7]金衍,陈勉,柳贡慧,等.大位移井的井壁稳定力学分析[J].地质力学学报,1999,5(1):4-11.
[8]金衍,陈勉,陈治喜,等.弱面地层的直井井壁稳定力学模型[J].钻采工艺,1999,22(3):13-14.
[9]阳友奎,肖长富.不同地应力状态下水力压裂的破裂模式[J].重庆大学学报(自然科学版),1993,16(3):30-35.
[10] LIU J Z,CHAO X L,LI Z Q. Shear fracturing during the process of hydrofractures[J]. Journal of Seismological Research,1984,7(2):253-262.
[11]刘建中,李自强.对水压致裂应力测量理论的实验与分析[J].岩石力学与工程学报,1986,5(3):267-276.
[12]闫传梁,谢玉洪,邓金根,等.安全钻井液密度上限的确定方法[J].天然气工业,2013,33(6):80-85.
[13]朴玉芝,赵素红.利用测井资料确定合理钻井液密度方法的研究[J].钻采工艺,1998,21(5):20-22.
[14]程远方,徐同台.安全泥浆密度窗口的确立及应用[J].石油钻探技术,1999,27(3):16-18.
[15]黄荣樽.水力压裂裂缝的起裂和扩展[J].石油勘探与开发,1981,8(5):62-74.