Article
Thermodynamics
Bing Bai, Hong-jian Ni, Xian Shi, Xing Guo, Lu Ding
Summary: The study reveals that ScCO2 immersion decreases the compressive strength but increases the elastic modulus of shale. ScCO2 alters the mechanical properties of shale through pressure, adsorption, and dissolution, with adsorption being the dominant factor enhancing the elastic modulus.
Article
Energy & Fuels
Ning Li, Zhijun Jin, Shicheng Zhang, Haibo Wang, Peng Yang, Yushi Zou, Tong Zhou
Summary: By conducting high-temperature and high-pressure immersion experiments and grid nanoindentation tests on calcareous laminated shale samples, the impacts of water/supercritical CO2-rock interaction on the micro-mechanical properties of shale were investigated. The results showed that the damage to shale caused by this interaction was mainly characterized by the generation of induced fractures in clay-rich laminae. The presence of induced fractures led to a decrease in elastic modulus and hardness, and the extent of degradation increased with longer soaking time, higher pressure, and temperature. Compared to water-rock interaction, supercritical CO2-rock interaction caused less mechanical damage on the shale surface, making it a potential fracturing fluid for shale reservoirs.
PETROLEUM EXPLORATION AND DEVELOPMENT
(2023)
Article
Thermodynamics
Kang Yang, Junping Zhou, Xuefu Xian, Lei Zhou, Chengpeng Zhang, Shifeng Tian, Zhaohui Lu, Fengshou Zhang
Summary: This study investigates the impact of ScCO2-water exposure on shale properties and reveals the changes in mineral composition, pore structure, and mechanical properties due to the chemical-mechanical interaction. The results indicate that the interaction leads to changes in shale porosity and permeability, with chemical reactions increasing the porosity in unstressed conditions and the chemical-mechanical coupling effects decreasing the permeability in stressed conditions. The findings highlight the importance of understanding the chemical-mechanical processes in shale for optimizing gas recovery and CO2 sequestration.
Article
Energy & Fuels
Junping Zhou, Kang Yang, Lei Zhou, Yongdong Jiang, Xuefu Xian, Chengpeng Zhang, Shifeng Tian, Maolin Fan, Zhaohui Lu
Summary: This study investigates the influence of sub/super-critical CO2-water exposure on the microstructure and mechanical properties of shale. The results show that CO2 exposure leads to a decrease in carbonate and clay content in shale, while altering pore structures and reducing the mechanical properties of the shale. Additionally, the study finds that greater alterations in the pore structure and mechanical properties are induced by supercritical CO2 compared to subcritical CO2, and these alterations are further enhanced by CO2-water exposure.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2021)
Article
Thermodynamics
Song Weiqiang, Ni Hongjian, Tang Peng, Zhang Shichuan, Gao Jichao, Zhang Junming, Shen Baotang
Summary: Laboratory experiments were conducted to measure the influence of carbon dioxide immersion on shale rock's properties, and the coupling mechanism between stress and seepage during hydraulic fracturing was simulated based on cohesive zone model. The results showed that the elastic modulus of shale increased, Poisson's ratio decreased, and compressive strength decreased after geothermal reaction with carbon dioxide. Compared with water fracturing, carbon dioxide fracturing induces longer and narrower fractures. The influence of viscosity of carbon dioxide on fracture width and length is negligible, validating the stable feasibility of carbon dioxide fracturing.
JOURNAL OF THERMAL SCIENCE
(2021)
Article
Energy & Fuels
Saad Alafnan
Summary: This study investigates the impact of supercritical carbon dioxide injection on the geomechanics of kerogen in shale formations. It reveals that the injection of supercritical carbon dioxide alters the mechanical behavior of kerogen, leading to a decrease in ductility under applied stress. This research provides nano-scale insights into the advantages of using supercritical carbon dioxide to degrade the mechanical integrity of organic matters contained in shales, supporting the value of carbon dioxide sequestration in shale formations.
Article
Energy & Fuels
Xiaofei Wang, Shaobin Hu, Enyuan Wang
Summary: Supercritical CO2 pneumatic fracturing technology shows promising applications in petroleum and shale gas extraction. A true triaxial experimental system was developed to study the fracturing effect of different polyenergy agent dosage and CO2 pressure. The study found that an increase in initial CO2 pressure improved the fracturing effect, while the effect remained unchanged with increased initial pressure at sufficient dosage. Tensile stresses from shock wave reflection were identified as the cause of micro-annular cracks. The fractal dimension provided a comprehensive description of the damage, making it a useful damage variable for characterizing the fracture morphology.
Article
Energy & Fuels
Bryan X. Medina, Arjun Kohli, Anthony R. Kovscek, Vladimir Alvarado
Summary: Characterizing the pore structures and transport properties of low-permeability shales is critical for evaluating these formations as potential seals or storage sites for geological CO2 sequestration. The study used low-pressure gas adsorption and nuclear magnetic resonance (NMR) techniques to characterize the pore-size distribution of shales before and after injection of supercritical CO2. Results showed that supercritical CO2 injection alters the pore-size distribution for pore sizes <1 nm to 1 mm, providing insights on the evolution of pore structure and mass transport properties during storage of supercritical CO2 in different shale lithologies.
Article
Chemistry, Multidisciplinary
Jinzhang Jia, Hailong Song, Peng Jia
Summary: In this study, adsorption simulations were conducted to investigate the amount and control mechanism of methane adsorbed by different coal rank coals. The results showed that the adsorption of methane was mainly concentrated in the effective pores of coal molecules, and the isosteric heat exhibited an exponential relationship with adsorption pressure.
Article
Thermodynamics
Chao Qin, Yongdong Jiang, Junping Zhou, Shuangying Zuo, Shiwan Chen, Zhengjie Liu, Hong Yin, Ye Li
Summary: This study investigates the influence of supercritical CO2 (ScCO2) injection on the water wettability of shale. The results show that the water contact angles of shale generally increase and the wettability weakens after ScCO2 exposure. This change may have positive effects on gas seepage but negative effects on CGS stability.
Article
Chemistry, Multidisciplinary
Siwei Meng, Xu Jin, Jiaping Tao, Xiaoqi Wang, Chenjun Zhang
Summary: The study investigates the effects of supercritical carbon dioxide (SC-CO2) treatment on shale samples from the Songliao Basin in China, revealing that SC-CO2 treatment leads to a gradual decrease in the mechanical properties of shale, primarily due to a loss in elastic modulus and changes in mineral composition.
Article
Energy & Fuels
Shoaib Memon, Runhua Feng, Muhammad Ali, Masood Ahmed Bhatti, Ausama Giwelli, Alireza Keshavarz, Quan Xie, Mohammad Sarmadivaleh
Summary: It has been found that the interaction between supercritical CO2 and shale during hydraulic fracturing can alter the petrophysical properties of the rock and result in a reduction of fracture aperture, thereby decreasing the post-fracturing productivity of the rock.
Article
Geosciences, Multidisciplinary
Hongyan Yu, Maxim Lebedev, Jinyu Zhou, Minghui Lu, Xiaolong Li, Zhenliang Wang, Tongcheng Han, Yihuai Zhang, Lukman M. Johnson, Stefan Iglauer
Summary: Rock mechanical properties play a crucial role in shale reservoirs, influencing production efficiency and hydraulic fracturing design. However, there is limited data on rock mechanical properties in lacustrine shales. This study explores the differences between argillaceous shales and silty laminae shales through petrophysical and rock mechanical tests. The results show that the content of mixed illite/smectite and organic matter strongly affects the rock mechanical properties of lacustrine shales. Furthermore, texture and micro-structure determine the fracture complexity of shale reservoirs. High clay content in lacustrine shales allows for extensive fracturing and potentially economic production.
MARINE AND PETROLEUM GEOLOGY
(2022)
Article
Thermodynamics
Chao Qin, Yongdong Jiang, Mengyao Cao, Junping Zhou, Xiao Song, Shuangying Zuo, Shiwan Chen, Yahuang Luo, Siyou Xiao, Hong Yin, Xidong Du
Summary: This study investigates the desorption-diffusion behaviors of CH4 in shale after supercritical CO2 injection, and finds that ScCO2 exposure can enhance the desorption and diffusion of CH4 in shale, with slight dependence on exposure pressure and temperature.
Article
Energy & Fuels
Arash Kamali-Asl, Mark D. Zoback, Arjun H. Kohli
Summary: The study observed a negative correlation between initial permeability and carbonate content in the formations. Clay- and organic-rich samples experienced a reversible decrease in permeability due to matrix swelling from adsorption of scCO(2), while carbonate-rich samples showed an irreversible increase in permeability from dissolution of carbonate minerals. Flow of scCO(2) through mu m-scale cracks plays a key role in determining matrix permeability and pressure dependence.
