桑峰军, 程汉列, 张晓燕,等.基于应力应变曲线的页岩脆性指标分析[J].河南理工大学学报（自然科学版）,2021,40(5):63-70.

SANG F J, CHENG H L, ZHANG X Y,et al.Study on brittleness index of shale based on stress-strain curve[J].Journal of Henan Polytechnic University(Natural Science) ,2021,40(5):63-70.

基于应力应变曲线的页岩脆性指标分析

桑峰军1, 程汉列2, 张晓燕3, 杨国平3, 赵建锋3, 符彩云3, 张冲3

1.中石化中原石油工程有限公司 工程服务管理中心，河南 濮阳 457001;2.中海艾普油气测试（天津）有限公司，天津 300457;3.中国石油长庆油田分公司，陕西 榆林 719000

摘要:页岩脆性是评价页岩气储层是否可压的一个重要指标，是储层能否实现商业开采的关键。以南方海相龙马溪组富有机质页岩为研究对象，开展了单三轴压缩试验，依据岩石应力应变曲线建立新的脆性评价指标，并进行验证，在此基础上研究了页岩的脆性各向异性特征，结果表明：提出的脆性指标可以较好地反映页岩的脆性特征，标准化系数分别取λ=0. 4和n = 0.6时效果最好；南方海相龙马溪组页岩储层具有较强的脆性特征，可将其划分为高可压性储层；页岩的脆性指标随着围压增加逐渐降低，降低的速率逐渐减小；页岩的应力应变曲线5个阶段比较明显，随着围压增加，压密阶段逐渐缩短，屈服阶段逐渐变长，残余强度随着围压几乎线性增加；随着围压增加，页岩的峰值强度、弹性模量和软化模量都表现出明显的增加趋势，增幅分别为105.17％，71.74％和97.75％；页岩的脆性指标随着层理倾角增加先减小后增加，表现出“U”形变化规律，在层理倾角θ=0°时取得最大值，θ=30°时取得最小值，各向异性系数高达1.991，具有明显的各向异性特征。

关键词:龙马溪组页岩;脆性指标;单三轴压缩试验;力学参数;应力应变曲线;各向异性

doi:10.16186/j.cnki.1673-9787.2020010065

基金项目:国家科技重大专项资助项目（2016ZX05062004）

收稿日期:2020/01/21

修回日期:2020/04/21

出版日期:2021/09/15

Study on brittleness index of shale based on stress-strain curve

SANG Fengjun1, CHENG Hanlie2, ZHANG Xiaoyan3, YANG Guoping3, ZHAO Jianfeng3, FU Caiyun3, ZHANG Chong3

1.Petroleum Engineering Management Co. Ltd， Sinopec Zhong-yuan Oilfield Service Corporation， Puyang  457001 ， Henan， China;2.COSL-EXPRO Testing Services（Tianjin） Co. ， Ltd. ， Tianjin  300457 ， China;3.PetroChina Changqing Oilfield Company， Yulin  719000 ， Shaanxi， China

Abstract:The brittleness of shale is a key indicator for evaluating the compressibility of shale reservoirs ， and is the key to decide whether shale reservoirs can be commercialized. In this work ， the uniaxial and triaxial com-pression tests of organic rich shale of marine Longmaxi formation in South China were carried out ， a new brittle-ness evaluation index was established and verified according to the rock stress-strain curve. On this basis ， the brittleness anisotropy characteristics of shale were studied. The results showed that the brittleness index could commendably reflect the brittleness characteristics of shale ， and the best results could be obtained when the normalization coefficients were λ =0.4 and n =0. 6 ， respectively； The shale reservoir of marine Longmaxi formation in south China had strong brittleness， which could be divided into high compressibility reservoir； The brittleness index decreased With the increase of confining pressure ， and the decreasing rate decreased gradually ； With the increase of confining pressure ， the compaction stage shortened and the yield stage became longer. The residual strength increased almost linearly with the increase of confining pressure ； With the increase of confining pressure ， the peak strength ， elastic modulus and softening modulus of shale showed a significant in-creasing trend ， with growing rate of 105.17% ，71.74% and 97.75% ， respectively. With the increase of the bedding angle ， the brittleness index of shale decreased first and then increased ， showing a “U” shape change law ， whose maximum value and minimum value were obtained when the bedding angle θ=0° and θ= 30° ， respectively. The anisotropy coefficient was as high as 1.991 ， which showed that the brittleness of shale had obvious anisotropic characteristics.

Key words:Longmaxi formation shale;brittleness index;uniaxial compression test and triaxial compression test;mechanical parameter;stress-strain curve;anisotropic characteristic

基于应力应变曲线的页岩脆性指标分析_桑峰军.pdf