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η=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。
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 compression tests of organic rich shale of marine Longmaxi formation in South China were carried out,a new brittleness 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 wereλ=0.4 andη=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 increasing 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 angleθ=0°andθ=30°,respectively.The anisotropy coefficient was as high as 1.991,which showed that the brittleness of shale had obvious anisotropic characteristics.
作者
桑峰军
程汉列
张晓燕
杨国平
赵建锋
符彩云
张冲
SANG Fengjun;CHENG Hanlie;ZHANG Xiaoyan;YANG Guoping;ZHAO Jianfeng;FU Caiyun;ZHANG Chong(Petroleum Engineering Management Co.Ltd,Sinopec Zhongyuan Oilfield Service Corporation,Puyang457001,Henan,Chin;COSL-EXPRO Testing Services(Tianjin)Co.,Ltd.,Tianjin300457,China;Petro China Changqing Oilfield Company,Yulin719000,Shaanxi,China)
出处
《河南理工大学学报（自然科学版）》
CAS
北大核心
2021年第5期63-70,共8页
Journal of Henan Polytechnic University（Natural Science）
基金
国家科技重大专项资助项目(2016ZX05062004)。
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
Longmaxi formation shale
brittleness index
uniaxial compression test and triaxial compression test
mechanical parameter
stress-strain curve
anisotropic characteristic
