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力学与实践 ›› 2018, Vol. 40 ›› Issue (3): 273-280.doi: 10.6052/1000-0879-17-369

• 应用研究 • 上一篇    下一篇

基于塑性损伤理论的软泥页岩地层井壁稳定性分析1)

张鹏伟, 孙峰, 叶贵根, 薛世峰   

  1. 中国石油大学(华东) 储运与建筑工程学院,山东青岛266580
  • 收稿日期:2017-10-30 修回日期:2017-10-30 出版日期:2018-06-15 发布日期:2018-07-17
  • 作者简介:张鹏伟,研究方向为油气田地下工程力学。E-mail:zhangpengweiupc@163.com;薛世峰,教授,主要从事油气田地下工程力学研究。E-mail: xuesf@126.com

ANALYSIS OF THE WELLBORE STABILITY BASED ON PLASTIC DAMAGE THEORY IN SOFT SHALE FORMATION

ZHANG Pengwei, SUN Feng, YE Guigen, XUE Shifeng   

  1. College of Pipeline and Civil Engineering, China University of Petroleum, Qingdao 266580, Shandong, China
  • Received:2017-10-30 Revised:2017-10-30 Online:2018-06-15 Published:2018-07-17
  • Contact: 1) 国家自然科学基金(51304230),中央高校基本科研业务费专项(16CX05001A) 资助项目

摘要: 软泥页岩在地层高压、流体环境下独有的力学变形特性一直是井壁稳定性控制工程领域的研究热点。针对软泥页岩低强度、高塑性的特点,考虑孔隙渗流、塑性损伤引起的渗透率变化等因素,建立了渗流-- 应力耦合形式的井壁稳定性评价数值模型,研究了流体渗流、泥浆压力、水平应力差的影响。结果表明,对过平衡钻井,当泥浆压力超过地层孔隙压力10% 时,渗流-- 应力耦合效应导致井壁塑性损伤区扩大至少65%,需予以考虑。水平应力差的增大会促进井壁塑性损伤区向最小水平主应力方向集中,且损伤区深度增大。

关键词: 软泥页岩|塑性软化|井壁稳定|渗流-应力耦合|泥浆压力

Abstract: The unique mechanical deformation characteristics of the soft shale under a high pressure and in the hydraulic environment are always important issues of researches of the wellbore stability and control engineering.In view of low strength and high plasticity of the soft shale formation, a numerical evaluation model of the wellbore stability is established with consideration of the effects of the hydraulics-deformation coupling, the plastic damage and the permeability variation. The influences of the fluid seepage, the mud pressure and the horizontal stress difference on the wellbore stability are studied. It is shown that for overbalanced drilling, when the mud pressure exceeds ten percent of the formation pore pressure, the hydraulics-deformation coupling effect leads to an expansion of the plastic damage area, by at least sixty-five percent. Moreover, the increase of the horizontal stress difference promotes the plastic damage zone to concentrate in the direction of the minimum horizontal principal stress, and the damage zone becomes deeper.

Key words: soft shale|plastic strain softening|wellbore stability|hydraulics-deformation coupling|mud pres-sure

中图分类号: 

  • TE312