西南石油大学学报(自然科学版) ›› 2017, Vol. 39 ›› Issue (1): 161-168.DOI: 10.11885/j.issn.1674-5086.2015.07.10.24

• 石油机械与油田化学 • 上一篇    下一篇

基于真三轴强度准则分析页岩斜井坍塌风险

马天寿1,2, 杨子莘1,2, 陈平1,2, 郭昭学2   

  1. 1. "油气藏地质及开发工程"国家重点实验室·西南石油大学, 四川 成都 610500;
    2. 西南石油大学石油与天然气工程学院, 四川 成都 610500
  • 收稿日期:2015-07-10 出版日期:2017-02-01 发布日期:2017-02-01
  • 通讯作者: 马天寿,E-mail:matianshou@126.com
  • 作者简介:马天寿,1987年生,男,汉族,四川绵阳人,博士,主要从事油气井工程教学与科研工作。E-mail:matianshou@126.com;杨子莘,1989年生,男,汉族,湖北潜江人,博士研究生,主要从事油气井工程岩石力学方面的研究工作。E-mail:yangzixin211@163.com;陈平,1952年生,男,汉族,四川成都人,教授,博士生导师,主要从事定向井、丛式井、水平井、侧钻水平井等特殊油气井的钻井技术研究工作。E-mail:chenping@swpu.edu.cn;郭昭学,1974年生,男,四川自贡人,副教授,博士,主要从事油气井压力控制、钻井工程仿真模拟及钻井工程数据可视化应用相关理论研究与软件开发工作。E-mail:875514031@qq.com
  • 基金资助:
    国家重点基础研究发展计划(2013CB228003);国家自然科学基金(51604230);中国博士后科学基金资助项目(2016M600626);四川省国际科技合作与交流项目(2017HH0061,2016HH0001)。

Collapse Risk for Deviated Borehole in Shale Formations Based on True-triaxial Strength Criterion

MA Tianshou1,2, YANG Zixin1,2, CHEN Ping1,2, GUO Zhaoxue2   

  1. 1. State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chendu, Sichuan 610500, China;
    2. School of Petroleum and Natural Gas Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500, China
  • Received:2015-07-10 Online:2017-02-01 Published:2017-02-01

摘要: 井壁稳定性分析常采用Mohr-Coulomb(M-C)准则,由于其忽略了中间主应力(σ2)的影响,使得结果偏于保守。为此,给出一种考虑了σ2影响的真三轴Mogi-Coulomb(MG-C)准则,通过拟合Yuubari页岩真三轴实验数据,评价了M-C、Drucker-Prager(D-P)和MG-C准则的适用性;基于孔隙弹性斜井井壁应力分布模型,采用3种强度准则进行了斜井相对坍塌风险的分析。研究表明,MG-C准则拟合结果最好,能够准确反映σ2对强度的影响,岩石强度随σ2增加,先增加后下降;采用3种强度准则计算的斜井相对坍塌风险分布规律基本一致,M-C准则计算结果偏高,D-P准则计算结果偏低,而MG-C准则比较准确地考虑了σ2的影响,其计算结果比较适中,比较适合用于井壁坍塌压力分析。MG-C准则的材料常数可通过常规三轴岩石力学参数(内聚力和内摩擦角)计算得到,使得MG-C准则使用方便,采用测井资料分析井壁稳定可得到连续坍塌压力剖面。

关键词: 井壁稳定, 强度准则, Mogi-Coulomb, 页岩, 坍塌压力

Abstract: The Mohr-Coulomb(M-C)criterion is commonly used in the analysis of wellbore stability. Consequently, the result of wellbore stability analysis is conservative because the influence of intermediate principal stress(σ2) is ignored. Therefore, in this study, the influence of σ2 is considered to derive a true-triaxial Mogi-Coulomb(MG-C) criterion, and the applicability of the M-C, Drucker-Prager(D-P), and MG-C criteria were evaluated by fitting the true-triaxial data of the Yuubari shale. The relative collapse risk was analyzed for these three criteria based on the poro-elastic stress distribution model of the deviated well. The results show that the fitting result of MG-C is the best as it can accurately predict the influence of σ2, and the rock strength increases at first and then decreases with increasing σ2. The distribution rule of the relative collapse risk for deviated wellbore is basically the same for the above three criteria. The result of M-C is slightly higher, while that of D-P is slightly lower, and that of MG-C is optimal, which can accurately predict the impact of σ2. Thus, MG-C criterion is applicable to the analysis of collapse pressure. Moreover, the material constants of the MG-C criterion can be determined by conventional triaxial rock mechanics parameters(cohesion and friction angle), which led to MG-C convenience to apply. The wellbore stability can get a continuous collapse pressure profile with logging data analysis.

Key words: wellbore stability, strength criterion, Mogi-Coulomb, shale formations, collapse pressure

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