摘要
考虑到目前缺乏对深层页岩水化软化机制的认识和相应本构模型的研究,对四川盆地龙马溪组深层页岩开展室内试验和理论模型研究,建立水化作用下深层页岩软化本构模型。首先开展清水自由浸泡试验;然后对不同浸泡时间的岩样进行CT扫描,并绘制CT灰度直方图分析页岩水化细观损伤机制;再对泡水后的岩样进行三轴压缩试验;最后采用连续损伤力学和Weibull统计理论,建立高闭合压力下的页岩软化本构模型。试验结果表明,页岩水化损伤的主要原因是由于内部微裂隙萌生和扩展,在力学参数上表现为黏聚力、峰值强度和弹性模量等参数随水化时间的增加而降低,泊松比随着水化时间的增加而增加,而在应力-应变曲线中表现为压密阶段和屈服破坏阶段有明显的延长;模型参数m,F_(0)随水化时间的增加而减低,从宏观上解释了水化作用致使页岩力学性质软化这一特性。
Given the lack of the understanding for the hydration leads to softening mechanism of deep shale and the corresponding constitutive model,based on the laboratory experiment and theoretical model research on the deep shale of longmaxi formation in Sichuan Basin,establishing the softening constitutive model of hydration.Firstly,carrying out the experiment of free immersion in clean water.Then CT scanning is performed on rock samples with different soaking time,and CT gray histogram is drawn to analyze the meso-damage mechanism of hydration,and carrying out the triaxial compression test on soaking samples.Finally,establishing the softening constitutive model of shale under high closure pressure by using continuous damage mechanics and Weibull statistical theory.It is found that the main cause of shale hydration damage is the initiation and expansion of internal microcracks,the mechanical parameters,cohesion,peak strength and elastic modulus,decrease with the increase of hydration time,Poisson's ratio increase with the increase of hydration time.In the stress-strain curve,the compaction stage and yield failure stage are obviously prolonged,and the model parameters m and F_(0)decrease with the increase of hydration time,which macroscopically explains the softening of shale mechanical properties caused by hydration.
作者
赵志红
金浩增
郭建春
陈孟婷
卢聪
ZHAO Zhihong;JIN Haozeng;GUO Jianchun;CHEN Mengting;LU Cong(State Key Laboratory of Oil and Gas Reservoir Geology and Development Engineering,Southwest Petroleum University,Chengdu,Sichuan 610500,China;Petroleum Engineering Institute of Sinopec Shanghai Offshore Oil and Gas Company,Shanghai 200120,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2022年第S02期3189-3197,共9页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(52022087)
关键词
岩石力学
页岩
水化作用
损伤力学
统计理论
rock mechanics
shale
hydration
damage mechanics
statistical theory
作者简介
赵志红(1981-),男,2011年毕业于西南石油大学油气田开发专业,现任副教授、硕士研究生导师,主要从事低渗和非常规油气藏增产理论与技术及现场应用方面的研究工作。E-mail:swpuzzh@163.com
