基于真三轴强度准则分析页岩斜井坍塌风险

发布时间：2018-03-04 15:10

本文选题：井壁稳定　切入点：强度准则　出处：《西南石油大学学报(自然科学版)》2017年01期 　论文类型：期刊论文

【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(σ_2)的影响,使得结果偏于保守。为此,给出一种考虑了σ_2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σ_2对强度的影响,岩石强度随σ_2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σ_2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。
[Abstract]:The Mohr Coulombn M-C criterion is often used in wellbore stability analysis, which ignores the effect of intermediate principal stress (蟽 2) and makes the results conservative. Therefore, a true triaxial Mogi Coulomb MG-C criterion considering the effect of 蟽 2 is presented, and the true triaxial experimental data of Yuubari shale are fitted by fitting the true triaxial experimental data. The applicability of M-C Drucker Prager(D P) and MG-C criterion is evaluated, and the relative collapse risk of inclined well is analyzed by three strength criteria based on the stress distribution model of borehole lining. The results show that the MG-C criterion is the best. It can accurately reflect the effect of 蟽 _ 2 on strength, the rock strength increases with 蟽 _ 2 and then decreases, and the relative collapse risk distribution of inclined wells calculated by three strength criteria is basically consistent with that calculated by M-C criterion, and the results of D-P criterion are lower than that of M-C criterion. The MG-C criterion considers the effect of 蟽 _ s _ 2 accurately, and its calculation results are relatively moderate. The material constants suitable for the wellbore collapse pressure analysis .MG-C criterion can be calculated by the conventional triaxial rock mechanics parameters (cohesion force and friction angle). The MG-C criterion is convenient to use and the continuous collapse pressure profile can be obtained by using log data to analyze wellbore stability.
【作者单位】： "油气藏地质及开发工程"国家重点实验室·西南石油大学;西南石油大学石油与天然气工程学院;
【基金】：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)
【分类号】：TE21

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