Effects of SC-CO2 and Brine on the Anisotropic  Mechanical Properties of Shale

Ma Tianshou; Feng Jie; Liu Yang

doi:10.20174/j.JUSE.2026.01.10

Chinese Journal of Underground Space and Engineering >

2026 , Vol. 22 >Issue 1: 91 - 102

DOI: https://doi.org/10.20174/j.JUSE.2026.01.10

Effects of SC-CO₂ and Brine on the Anisotropic Mechanical Properties of Shale

Ma Tianshou ,
Feng Jie ,
Liu Yang

Expand

1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, P.R. China;
2. Key Laboratory of Oil & Gas Equipment, Ministry of Education, Southwest Petroleum University, Chengdu 610500, P.R. China

Received date: 2025-02-16

Online published: 2026-03-03

Fold

Abstract

The process of CO₂ waterless fracturing and enhanced production of shale gas involves a physical and chemical reaction between supercritical carbon dioxide (SC-CO₂), brine, and shale rock, and this reaction can alter the physical and mechanical properties of shale rock. However, there has been limited investigation into the evolution of anisotropic mechanical characteristics. Therefore, uniaxial compression experiments were conducted on shale samples with varying bedding angles, soaked in SC-CO₂ + brine for different durations. The evolution of shale strength, elasticity, failure mode, acoustic emission (AE) signal, and fractal dimension under varying bedding angles and soaking times was analyzed, and the evolution characteristics of shale anisotropy were defined. The results indicate that: An increase in soaking time results in a notable softening of the complete stress-strain curve, accompanied by a gradual decline in uniaxial strength and elastic modulus, a gradual increase in peak strain and Poisson's ratio, and a gradual intensification of the shale dilatation phenomenon. The AE signals in the compaction and yield failure stages are significantly enhanced following soaking. The AE fractal dimension is observed to increase with the increase of bedding inclination and soaking time. This indicates that the complexity and irregularity of shale deformation and failure are stronger after soaking. The shale failure mode is closely related to the bedding inclination and soaking time. For bedding inclinations of 45° and 60°, shear failure along the bedding plane is the predominant mode of failure, and the shale failure that occurs after soaking is prone to produce more secondary cracks, resulting in a more thorough degree of shale failure. Following prolonged immersion of SC-CO₂ + brine, the anisotropy of shale strength, elasticity, acoustic emission signal, and acoustic emission fractal dimension is markedly augmented. This phenomenon can be attributed to the ease with which SC-CO₂ + brine invades along the bedding plane, thereby continuously weakening interbedding cementation. This, in turn, results in a gradual increase in the difference between the bedding plane and the matrix, which significantly enhances the anisotropy.

Key words： shale gas; supercritical carbon dioxide; brine; mechanical characteristic; acoustic emission; anisotropy

Cite this article

Ma Tianshou , Feng Jie , Liu Yang . Effects of SC-CO₂ and Brine on the Anisotropic Mechanical Properties of Shale[J]. Chinese Journal of Underground Space and Engineering, 2026 , 22(1) : 91 -102 . DOI: 10.20174/j.JUSE.2026.01.10

References

[1] 贾承造, 姜林, 赵文. 页岩油气革命与页岩油气、致密油气基础地质理论问题[J]. 石油科学通报, 2023, 8(6): 695-706. (Jia Chengzao, Jiang Lin, Zhao Wen. The shale revolution and basic geological theory problems of shale and tight oil and gas[J]. Petroleum Science Bulletin, 2023, 8(6): 695-706. (in Chinese))
[2] 蒲秀刚, 付永强, 时战楠, 等. 断陷湖盆细粒区页岩组构特征与页岩油富集成藏规律:以黄骅坳陷古近系为例[J]. 中南大学学报(自然科学版), 2024, 55(3): 994-1007. (Pu Xiugang, Fu Yongqiang, Shi Zhannan, et al. Fabric characteristics and oil accumulation laws of shales in fine-grained areas of faulted lacustrine basin: a case of Paleogene in Huanghua Depression[J]. Journal of Central South University (Science and Technology), 2024, 55(3): 994-1007. (in Chinese))
[3] 赵金洲, 雍锐, 胡东风, 等. 中国深层—超深层页岩气压裂: 问题、挑战与发展方向[J]. 石油学报, 2024, 45(1): 295-311. (Zhao Jinzhou, Yong Rui, Hu Dongfeng, et al. Deep and ultra-deep shale gas fracturing in China: problems, challenges and directions[J]. Acta Petrolei Sinica, 2024, 45(1): 295-311. (in Chinese))
[4] 聂海宽, 党伟, 张珂, 等. 中国页岩气研究与发展20年:回顾与展望[J]. 天然气工业, 2024, 44(3): 20-52. (Nie Haikuan, Dang Wei, Zhang Ke, et al. Two decades of shale gas research & development in China: Review and prospects[J]. Natural Gas Industry, 2024, 44(3): 20-52. (in Chinese))
[5] 许冬进, 张滨海, 李紫晗, 等. 致密气压裂液与储层全过程渗吸伤害规律研究[J]. 长江大学学报(自然科学版), 2022, 19(1): 79-85. (Xu Dongjin, Zhang Binhai, Li Zihan, et al. Study on the law of imbibition damage in the whole process of tight gas fracturing fluid and reservoir[J]. Journal of Yangtze University (Natural Science Edition), 2022, 19(1): 79-85. (in Chinese))
[6] 王梓麟, 时婧玥, 徐栋, 等. 煤储层无水压裂技术现状及展望[J]. 钻采工艺, 2024, 47(1): 80-86. (Wang Zilin, Shi Jingyue, Xu Dong, et al. Research status and prospects of waterless fracturing technology in coal reservoir[J]. Drilling & Production Technology, 2024, 47(1): 80-86. (in Chinese))
[7] 刘卫彬, 徐兴友, 刘畅, 等. 超临界CO₂+水力携砂复合体积压裂工艺对陆相页岩储层的改造机理及效果[J]. 石油学报, 2022, 43(3): 399-409. (Liu Weibin, Xu Xingyou, Liu Chang, et al. The stimulation mechanism and performance analysis of supercritical CO₂ and hydraulic sand-carrying composite volume fracturing technology on continental shale reservoirs[J]. Acta Petrolei Sinica, 2022, 43(3): 399-409. (in Chinese))
[8] 左罗, 韩华明, 蒋廷学, 等. 页岩二氧化碳压裂裂缝扩展机制及工艺研究[J]. 钻采工艺, 2021, 44(5): 45-49. (Zuo Luo, Han Huaming, Jiang Tingxue, et al. Research on propagation mechanism and technology of carbon dioxide fracturing in shale gas[J]. Drilling and Production Technology, 2021, 44(5): 45-49. (in Chinese))
[9] 霍宏博, 刘东东, 陶林, 等. 基于CO₂提高采收率的海上CCUS完整性挑战与对策[J]. 石油钻探技术, 2023, 51(2): 74-80. (Huo Hongbo, Liu Dongdong, Tao Lin, et al. Integrity challenges and countermeasures of the offshore CCUS based on CO₂-EOR[J]. Petroleum Drilling Techniques, 2023, 51(2): 74-80. (in Chinese))
[10] Jayasekara D W, Ranjith P G,Wanniarachchi W A M, et al. CO₂-brine-caprock interaction: Reactivity experiments on mudstone caprock of South-west Hub geo-sequestration project[J]. Journal of Petroleum Science and Engineering, 2020, 189: 107011.
[11] Zhou J, Yang K, Zhou L, et al. Microstructure and mechanical properties alterations in shale treated via CO₂/CO₂-water exposure[J]. Journal of Petroleum Science and Engineering, 2021, 196: 108088.
[12] 王晓燕, 赵贤正, 周立宏, 等. 水平井+CO₂吞吐改善中低渗稠油油藏开发效果机制解析——以大港油田刘官庄埕隆1601区块为例[J]. 石油科学通报, 2023, 8(2): 166-178. (Wang Xiaoyan, Zhao Xianzheng, Zhou Lihong, et al. Mechanism analysis of horizontal well + CO₂ huff and puff to improve the development effect in medium and low permeability heavy oil reservoirs—A case from Liu Guan-zhuang Chenglong 1601 Block in Dagang Oilfield as an example[J]. Petroleum Science Bulletin, 2023, 8(2): 166-178. (in Chinese))
[13] 邓佳, 张奇, 王栋, 等. 压力驱动条件下页岩微纳米孔隙CO₂/CH₄竞争吸附特性[J]. 东北石油大学学报, 2021, 45(5): 109-116. (Deng Jia, Zhang Qi, Wang Dong, et al. Competitive adsorption characteristics of CO₂/CH₄ in micro-nano pores by pressure-driven for shale reservoir[J]. Journal of Northeast Petroleum University, 2021, 45(5): 109-116. (in Chinese))
[14] 赵玉龙, 黄义书, 张涛, 等. 页岩气藏超临界CO₂压裂—提采—封存研究进展[J]. 天然气工业, 2023, 43(11): 109-119. (Zhao Yulong, Huang Yishu, Zhang Tao, et al. Research progress on supercritical CO₂ fracturing, enhanced gas recovery and storage in shale gas reservoirs[J]. Natural Gas Industry, 2023, 43(11): 109-119. (in Chinese))
[15] 田时锋, 周军平, 鲜学福, 等. 超临界CO₂作用下页岩抗拉强度的变化规律[J]. 煤炭学报, 2023, 48(7): 2728-2736. (Tian Shifeng, Zhou Junping, Xian Xuefu, et al. Effect of supercritical CO2 on alteration of tensile strength of shale[J]. Journal of China Coal Society, 2023, 48(7): 2728-2736. (in Chinese))
[16] 李宁, 金之钧, 张士诚, 等. 水/超临界二氧化碳作用下的页岩微观力学特性[J]. 石油勘探与开发, 2023, 50(4): 872-882. (Li Ning, Jin Zhijun, Zhang Shicheng, et al. Micro-mechanical properties of shale due to water/supercritical carbon dioxide-rock interaction[J]. Petroleum Exploration and Development, 2023, 50(4): 872-882. (in Chinese))
[17] 杨圣奇, 洪王星, 孙博文, 等. 不同盐水环境下页岩三轴力学及破坏特性试验研究[J]. 岩土工程学报, 2023, 45(11): 2217-2226. (Yang Shengqi, Hong Wangxing, Sun Bowen, et al. Experimental study on triaxial mechanics and failure characteristics of shale in different brine environments[J]. Chinese Journal of Geotechnical Engineering, 2023, 45(11): 2217-2226. (in Chinese))
[18] Zhou D, Zhang G, Huang Z, et al. Changes in microstructure and mechanical properties of shales exposed to supercritical CO₂ and brine[J]. International Journal of Rock Mechanics and Mining Sciences, 2022, 160: 105228.
[19] Tan J, Hu C, Lyu Q, et al. Multi-fractal analysis for the AE energy dissipation of CO₂ and CO₂+brine/water treated low-clay shales under uniaxial compressive tests[J]. Fuel, 2019, 246: 330-339.
[20] 罗鸣, 高德利, 黄洪林, 等. 钻井液对页岩力学特性及井壁稳定性的影响[J]. 石油钻采工艺, 2022, 44(6): 693-700. (Luo Ming, Gao Deli, Huang Honglin, et al. Effects of drilling fluids on shale mechanical properties and wellbore stability[J]. Oil Drilling & Production Technology, 2022, 44(6): 693-700. (in Chinese))
[21] Guo Y D, Li X B, Huang L Q, et al. Effect of water-based working fluid imbibition on static and dynamic compressive properties of anisotropic shale[J]. Journal of Natural Gas Science and Engineering, 2021, 95: 104194.
[22] 洪王星. 不同盐水环境下页岩力学行为及破坏机理研究[D]. 徐州: 中国矿业大学, 2023. (Hong Wangxing. Study on Mechanical Behavior and Damage Mechanism of Shale in Different Saline Environments[D]. Xuzhou: China University of Mining and Technology, 2023. (in Chinese))
[23] 白冰, 倪红坚, 郭兴, 等. 超临界二氧化碳作用下层理倾角对页岩力学性质影响试验研究[A]//2018油气田勘探与开发国际会议[C]. 2018: 1-10. (Bai Bing, Ni Hongjian, Guo Xing, et al. Experimental study on effect of bedding dig angle on mechanical properties of shale in supercritical carbon dioxide[A]// 2018 International Field Exploration and Development Conference [C]. 2018: 1-10. (in Chinese))
[24] 马天寿, 王浩男, 杨赟, 等. 不同地应力状态下各向异性地层斜井井壁破裂规律[J]. 中南大学学报(自然科学版), 2022, 53(3): 1123-1135. (Ma Tianshou, Wang Haonan, Yang Yun, et al. Wellbore fracture regularity of inclined wells in anisotropic formation under different in-situ stress states[J]. Journal of Central South University (Science and Technology), 2022, 53(3): 1123-1135. (in Chinese))
[25] 张伯虎, 马浩斌, 田小朋, 等. 层状页岩力学参数的各向异性研究[J]. 地下空间与工程学报, 2020, 16(增2): 634-638. (Zhang Bohu, Ma Haobin, Tian Xiaopeng, et al. Deep layered shale mechanical parameters anisotropy study[J]. Chinese Journal of Underground Space and Engineering, 2020, 16(Supp. 2): 634-638. (in Chinese))
[26] Stanley D, Christensen N I. Attenuation anisotropy in shale at elevated confining pressures[J]. International Journal of Rock Mechanics and Mining Sciences, 2001, 38(7): 1047-1056.
[27] 刘文革, 尹成, 陈康, 等. 川东南页岩气储层的岩石物理特征分析[J]. 西南石油大学学报(自然科学版), 2024, 46(3): 27 36. (Liu Wenge, Yin Cheng, Chen Kang, et al. Rock physics characteristics of shale gas reservoir in Southeast Sichuan[J]. Journal of Southwest Petroleum University (Science & Technology Edition), 2024, 46(3): 27-36. (in Chinese))
[28] Lyu Q, Wang K, Hu C, et al. Effects of supercritical CO₂/water imbibition under dynamic pressures on shale mechanics and acoustic emission characteristics[J]. Fuel, 2022, 321: 124087.
[29] Blake O O, Faulkner D R, Tatham D J. The role of fractures, effective pressure and loading on the difference between the static and dynamic Poisson's ratio and Young's modulus of Westerly granite[J]. International Journal of Rock Mechanics and Mining Sciences, 2019, 116: 87-98.
[30] 马天寿, 王浩男, 刘梦云, 等. 页岩抗张力学行为各向异性实验与理论研究[J]. 中南大学学报(自然科学版), 2020, 51(5): 1391-1401. (Ma Tianshou, Wang Haonan, Liu Mengyun, et al. Experimental and theoretical investigation on anisotropy of shale tensile mechanical behaviors[J]. Journal of Central South University (Science and Technology), 2020, 51(5): 1391-1401. (in Chinese))
[31] Li Z, Suo J, Fan J, et al. Damage evolution of rock salt under multilevel amplitude creep-fatigue loading with acoustic emission monitoring[J]. International Journal of Rock Mechanics and Mining Sciences, 2023, 164: 105346.
[32] Zhou J, Tian S, Zhou L, et al. Effect of sub-/super-critical CO₂ and brine exposure on the mechanical and acoustic emission characteristics of shale[J]. Journal of Natural Gas Science and Engineering, 2021, 90: 103921.
[33] Hurst H E. Long-term storage capacity of reservoirs[J]. Transactions of the American Society of Civil Engineers, 1951, 116(1): 770-799.
[34] Niandou H, Shao J F, Henry J P, et al. Laboratory investigation of the mechanical behaviour of Tournemire shale[J]. International Journal of Rock Mechanics and Mining Sciences, 1997, 34(1): 3-16.
[35] 马天寿. 页岩气水平井井眼坍塌失稳机理研究[D]. 成都: 西南石油大学, 2015. (Ma Tianshou. Research on the mechanisms of borehole collapse instability for horizontal wells in shale gas reservoirs[D]. Chengdu: Southwest Petroleum University, 2015. (in Chinese))
[36] 霍健, 王星皓, 罗超, 等.川南地区龙马溪组页岩储层裂缝特征[J]. 工程地质学报, 2021, 29(1): 171-182. (Huo Jian, Wang Xinghao, Luo Chao, et al. Fracture characteristics of Longmaxi shale in southern Sichuan[J]. Journal of Engineering Geology, 2021, 29(1): 171-182. (in Chinese))
[37] Goodman A,Sanguinito S, Tkach M, et al. Investigating the role of water on CO₂-Utica Shale interactions for carbon storage and shale gas extraction activities-Evidence for pore scale alterations[J]. Fuel, 2019, 242: 744-755.
[38] Zhou J, Tian S, Xian X, et al. Comprehensive review of property alterations induced by CO₂ shale interaction: Implications for CO₂ sequestration in shale[J]. Energy & Fuels, 2022, 36(15): 8066-8080.
[39] 熊健, 李羽康, 刘向君, 等. 水岩作用对页岩岩石物理性质的影响—以四川盆地下志留统龙马溪组页岩为例[J]. 天然气工业, 2022, 42(8): 190-201. (Xiong Jian, Li Yukang, Liu Xiangjun, et al. Influences of water-rock interaction on the physical and mechanical properties of shales: A case study of the Lower Silurian Longmaxi Formation in the Sichuan Basin[J]. Natural Gas Industry, 2022, 42(8): 190-201. (in Chinese))
[40] Zhang Q, Fan X, Chen P, et al.Geomechanical behaviors of shale after water absorption considering the combined effect of anisotropy and hydration[J]. Engineering Geology, 2020, 269: 105547.

Options

Outlines

模态框（Modal）标题

Abstract

Cite this article

References