Article
Geochemistry & Geophysics
Xiaofei Fu, Lei Gong, Xiaocen Su, Bo Liu, Shuai Gao, Jianguo Yang, Xinnan Qin
Summary: This study systematically analyzes the controlling factors of fracture distribution in the continental shale of the Qingshankou Formation in the Songliao Basin, China. These factors include internal factors (mineral composition, mechanical stratigraphy, lithofacies) and external factors (faults, abnormally high pressure). Mineral composition is the primary factor governing fracture development, mechanical stratigraphy determines the spatial morphology of fractures, and lithofacies can influence fracture development by controlling mineral composition. Faults and abnormally high pressure also have an impact on fracture distribution.
Article
Energy & Fuels
Shang -Wen Zhou, Dong-Xiao Zhang
Summary: Deep shale gas (3500-4500 m) in China is expected to contribute significantly to the growth of shale gas production. The gas occurrence characteristics of deep shale reservoirs differ from those of shallow and medium layers due to high temperature and high pressure. Methane is mainly adsorbed in the form of micropore filling, while the mesopores store most of the free gas in deep shales. Total organic carbon (TOC) and micropore specific surface area (SSA) are the key factors influencing the adsorption capacity of deep shale. The dominant gas in deep shale gas reservoirs is free gas, with a content ratio of approximately 58%.
Article
Geosciences, Multidisciplinary
Xiongqi Pang, Min Li, Boyuan Li, Tong Wang, Shasha Hui, Yang Liu, Guoyong Liu, Tao Hu, Tianwu Xu, Fujie Jiang, Hong Pang, Chenxi Wang
Summary: This paper thoroughly discusses the methodologies and technology for determining the shale oil recoverable resource evaluation parameters, particularly the shale oil content, movable oil ratio, and recovery factor. It also presents a quantitative estimation model for the movable oil ratio and assesses the recoverable shale oil resources in the Gaoliu area of Nanpu Sag using the volume method model and the Monte Carlo methodology.
EARTH-SCIENCE REVIEWS
(2023)
Article
Geosciences, Multidisciplinary
Xuehui Zhou, Ruyue Wang, Zhili Du, Jing Wu, Zhonghu Wu, Wenlong Ding, Ang Li, Zikang Xiao, Zixian Cui, Xinghua Wang
Summary: Based on the observations and testing data, this paper discusses the characteristics and controlling factors of fractures and their control on shale gas accumulation in the Lower Cambrian Niutitang Formation black shale reservoir of Well YX1 in the northern Guizhou Province. The results show that various types of fractures are present in the Niutitang Formation, and their formation is mainly controlled by major faults. Compared to other shale gas reservoirs, the Well YX1 reservoir has both geological sweet spots and engineering sweet spots, but deformation and faulting have caused the loss of shale gas and damage to the overpressure environment.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Energy & Fuels
He Tian, Lianbo Zeng, Shijie Ma, Hong Li, Zhe Mao, Yongmin Peng, Xiang Xu, Dongjun Feng
Summary: This study analyzes the characteristics and fluid properties of different types of natural fractures, revealing their effects on the enrichment and preservation of shale gas. Non-strata-bounded fractures enhance the vertical connectivity of shale reservoirs, while strata-bounded fractures contribute to the enrichment of shale gas. Bed-parallel fractures control the lateral migration of shale gas.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Geosciences, Multidisciplinary
Fujie Jiang, Lina Huo, Di Chen, Liu Cao, Renjie Zhao, Yuan Li, Tingwei Guo
Summary: This study presents a comprehensive compilation of shale pore structure and proposes a model for predicting the pore structure type based on geological features. The research reveals the heterogeneity and complex pore distribution in different types of shale, and highlights the importance of thermal maturation and mineral composition in shaping the pore structure.
EARTH-SCIENCE REVIEWS
(2023)
Article
Thermodynamics
Bin Nie
Summary: This paper systematically studies the characteristics of gas surface diffusion on the surface wall of microscale fractures in unconventional gas reservoirs. Two innovations are analyzed: the characteristics of gas surface diffusion inside planar microscale fractures and the influence of mixed gas effect on gas surface diffusion. The research results show that the fracture opening has a negligible influence on the thickness of the adsorption layer when it is 2 nm or 5 nm.
Article
Geosciences, Multidisciplinary
Yuqi Huang, Jinchuan Zhang, Peng Zhang, Xuan Tang, Junwei Yang
Summary: Marine-continental transitional shale strata in China, such as the Longtan shales, have high gas potential. The fractal dimensions of different pore sizes were calculated to analyze the pore structures of the Longtan shales. The macropores (>= 100 nm) were mainly inorganic with a complex structure, while the mesopores (50-100 nm) had a slightly higher proportion of organic pores and a medium complexity. The mini-micropores were mainly organic and had complex structures and rough surfaces, and they accounted for the highest proportion of the total pores.
FRONTIERS IN EARTH SCIENCE
(2023)
Article
Energy & Fuels
Yongliang Wang, Yifeng Duan, Xuguang Liu, Jin Huang, Nai Hao
Summary: This study simulated the hydrofracturing process of naturally fractured reservoirs using various numerical methods, investigating the impact of sensitivity factors on the intersection of hydraulic fractures and natural fractures on fracture network morphology and gas production.
Article
Energy & Fuels
Min Li, Xiongqi Pang, Liang Xiong, Tao Hu, Di Chen, Zhen Zhao, Shasha Hui, Yang Liu, Siyu Zhang
Summary: The study systematically analyzed the shale gas occurrence characteristics of deep high-over mature shales using the Longmaxi Formation as an example, and found that factors such as temperature, pressure, pore structure, and organic matter content have an influence on the occurrence characteristics of shale gas.
Article
Energy & Fuels
Jiale Xu, Songtao Wu, Jingdong Liu, Yujie Yuan, Jinggang Cui, Ling Su, Xiaohua Jiang, Jun Wang
Summary: This study focused on the pore evolution of organic-rich shales from the Permian Lucaogou Formation in Junggar Basin, China. The research identified 18 nanometers as the critical pore size boundary that connected different stages of pore evolution, and revealed that different pore size ranges were controlled by different diagenesis processes. The study also showed a three-phase pattern of pore evolution as thermal maturity increases, with different correlations between pore evolution and organic matter maturity in specific pore size ranges.
Article
Energy & Fuels
Xuewen Shi, Wei Wu, Qiuzi Wu, Kesu Zhong, Zhenxue Jiang, Huan Miao
Summary: This study investigates the enrichment mechanism and forming type of deep shale gas in the Longmaxi Formation shale in the Desheng-Yunjin Syncline area of the Sichuan Basin. The research analyzes the mineralogy, organic geochemistry, physical properties, and gas and water content of the shale, as well as the influence of sedimentation, structural conditions, and hydrogeological conditions on gas enrichment. The results show that the shale in this area is a good hydrocarbon source rock with specific characteristics. Tectonic activities and hydrodynamic conditions have a significant impact on shale gas enrichment.
Article
Energy & Fuels
Xianglu Tang, Zhenxue Jiang, Zhenglian Yuan, Yifan Jiao, Caihua Lin, Xiaoxue Liu
Summary: This study investigates the controlling effect of pore water on shale gas enrichment by systematically analyzing the characteristics of pore water in Quaternary shale in the Qaidam Basin, China. The study reveals that pore water plays a significant role in the formation, adsorption, flow, and occurrence of shale gas. This research is crucial for enhancing the geological theory of shale gas and guiding shale gas exploration.
Article
Engineering, Geological
Hai Qu, Shimao Tang, Ying Liu, Pengpeng Huang, Xiaoguang Wu, Zhonghua Liu, Chengying Li
Summary: The study shows that using liquid nitrogen (LN2) for shale fracturing can decrease the breakdown pressure, activate pre-existing fractures and bedding planes, and enhance formation permeability. Lower stress anisotropy, higher pumping rate, and lower bedding plane angle result in more complex fractures.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Energy & Fuels
Jianglin He, Lixia Zhu, Ankun Zhao, Dong Wang, Zhen Qiu, Ping Yang
Summary: This study investigates the reservoir conditions of lacustrine shale in the Sichuan Basin through experiments on samples from wells and outcrops. The results show that lacustrine shale has different pore characteristics compared to marine shale. The arrangement of pores in marine shale is affected by compaction, while lacustrine shale is characterized by under-compaction. The findings suggest that high-quality areas for lacustrine shale gas may be located in under-compacted regions influenced by upward fluid pressure.
Article
Geosciences, Multidisciplinary
Jingyi Wang, Fujie Jiang, Qinhong Hu, Chunlin Zhang, Xiaoguang Yang, Wuling Mo, Xirong Wang, Zhenguo Qi
Summary: The central and eastern Paleozoic Carboniferous Benxi Formation in the Ordos Basin, China's largest gas-producing area, poses challenges for exploration due to extreme diagenesis, complex pore structure, and strong heterogeneity. This study conducted qualitative and quantitative analyses to investigate the development and controlling factors of secondary porosity in the formation. The findings provide a basis for predicting favorable reservoirs in the tight sandstones of the Benxi Formation in the Ordos Basin.
MARINE AND PETROLEUM GEOLOGY
(2023)
Article
Geosciences, Multidisciplinary
Jianjiang Wen, Mengdi Sun, Ziang Cui, Jingyi Wang, Heng Zhang, Zhongxian Cai, Mehdi Ostadhassan, Qi Wang, Qinhong Hu
Summary: In this study, the oil charging characteristics and pore structure of the Lower Cambrian Xiaoerbulake Formation in the Tarim Basin were investigated. The results showed that the microbial dolomites had the highest oil charging force and smallest pore throat threshold, making them the most favorable lithofacies for the accumulation and migration of oil and gas.
MARINE AND PETROLEUM GEOLOGY
(2023)
Article
Geosciences, Multidisciplinary
Yuantao Gu, Quan Wan, Xiaoxia Li, Tao Han, Shuguang Yang, Qinhong Hu
Summary: This study investigates the variation of organic matter occurrence and the relationship between petroleum generation of organic matter and transformation of clay minerals in nanocomposites as a function of maturity. The results show that most shale samples are organic-rich and represent a thermal evolutionary process from oil-window mature to overmature. The structural investigation of nanocomposites reveals that organic carbon dominates the occurrence of organic matter and extends the traditional view of organic matter-clay association. The results contribute to a better understanding of diagenesis and organic-inorganic interactions in organic-rich shales.
JOURNAL OF EARTH SCIENCE
(2023)
Article
Engineering, Civil
Xiaoqing Yuan, Qinhong Hu, Xiang Lin, Chen Zhao, Qiming Wang, Yukio Tachi, Yuta Fukatsu, Shoichiro Hamamoto, Marja Siitari-Kauppi, Xiaodong Li
Summary: The effects of heterogeneity on mass transport in different rock samples were studied. It was found that as particle size decreases, the effective porosity of heterogeneous rocks increases, while the porosity of homogeneous rocks remains constant. Additionally, different rocks exhibit different affinities for tracers.
JOURNAL OF HYDROLOGY
(2023)
Article
Geosciences, Multidisciplinary
Kefei Chen, Rui Yang, Hanyong Bao, Tian Dong, Aoqi Jia, Qinhong Hu, Xiaowen Guo, Sheng He
Summary: In this study, the influence of paleoenvironmental conditions and diagenetic pathways on pore development of the Wufeng and Longmaxi Formations in shale is investigated. The results show that paleoenvironmental conditions determine the composition and content of minerals and organic matter in shale. Different shale lithofacies undergo various diagenetic events and evolution pathways, which ultimately affect pore generation and evaluation. The content of pores varies in different lithofacies, with siliceous shale containing abundant biogenic authigenic quartz and organic matter, mixed shale having fewer residual pores due to compaction, and clay-rich shale experiencing deformation and loss of primary pores. The amount of organic matter pores gradually decreases from the bottom of the formations to the upper section.
MARINE AND PETROLEUM GEOLOGY
(2023)
Article
Chemistry, Multidisciplinary
Qiming Wang, Qinhong Hu, Chen Zhao, Yang Wang, Tao Zhang, Jan Ilavsky, Mengdi Sun, Linhao Zhang, Yi Shu
Summary: Laboratory-scale analysis of natural rocks provides information about their physical characteristics, such as density, porosity, and pore structure. This study investigated the effect of sample size on the petrophysical properties of different rock samples using various experimental techniques. The results suggest that the sample size influences the pore structure changes during crushing and the fluid-to-pore connectivity.
Article
Energy & Fuels
Jingchao Luo, Jianping Yan, Majia Zheng, Wei Guo, Guanghai Zhong, Min Wang, Bin Geng, Qinhong Hu
Summary: This study investigates the influence of mineral composition and lamination on the occurrence and mechanical properties of shale in the Luzhou area of the Sichuan Basin. The results show that the quartz content has a positive correlation with Young's modulus, and the laminated layer enhances shale anisotropy and fracture trapping abilities. The study contributes to a better understanding of the rock mechanics and fracture evaluation of shale reservoirs.
Article
Energy & Fuels
Jingyi Wang, Qinhong Hu, Zhongxian Cai, Xiaohui Sun, Mengdi Sun, Cong Zhang, Wei Wei, Ziang Cui
Summary: A study on 12 lacustrine shale samples from Lucaogou Formation reveals that the mineral compositions and organic matter abundance influence the pore system development and retained oil distribution. The samples are dominated by mineral-related slit-shaped pores with a small amount of organic matter-hosted pores. Feldspar dissolution leads to abundant dissolved pores, improving reservoir properties. Quartz overgrowth negatively affects pore structure, while carbonates undergo dissolution and cementation processes. Mineral sizes are positively related to pore diameter, and source-proximal sedimentary microfacies with coarse components are more favorable for oil exploration. Retained oil primarily occurs as a thin film in pores with diameters of 100-1500 nm, while oil in smaller pores is adsorbed. The retained oil volume is affected by organic matter abundance, storage type, and material source-reservoir configurations.
Article
Geosciences, Multidisciplinary
Xiaoqing Yuan, Qinhong Hu, Furong Wang, Xiaowen Guo, Hua Huang
Summary: This study systematically describes the diagenetic processes, porosity evolution, and diagenetic facies of sandstone reservoirs in the Eocene Lower Xingouzui Formation (LXF) in two depressions in the Jianghan Basin. Petrographic, mineralogical, geochemical, and petrophysical analyses were applied to the samples obtained from the Qianjiang and Jiangling sags. The study revealed multiple phases of diagenesis and the development of abnormally high porosity and permeability zones in both sags.
MARINE AND PETROLEUM GEOLOGY
(2023)
Article
Geosciences, Multidisciplinary
Mengdi Sun, Xianggang Duan, Qing Liu, Tomasz P. Blach, Mehdi Ostadhassan, Bo Liu, Yeping Ji, Qinhong Hu, Zhejun Pan
Summary: This study investigates the pore-fracture connectivity in overmature marine shale samples using small-angle neutron scattering (SANS), repeated mercury intrusion capillary pressure (MICP), and field emission scanning electron microscopy (FE-SEM) imaging. The results show that sealing of the pore system by brittle minerals reduces overall pore connectivity within the shale matrix. The combination of MICP measurements and FE-SEM imaging provides a new evaluation method for pore-fracture connectivity. The study also reveals that a small fraction of pores in overmature shales are accessible to methane, and under high pressure, the density of methane in small pore spaces is greater than that of an ideal gas and forms nanoscale methane clusters.
MARINE AND PETROLEUM GEOLOGY
(2023)
Article
Energy & Fuels
Binqian Yin, Qinhong Hu, Yingying Zhu, Keren Zhou
Summary: In analyzing geological processes, segmenting SEM images of geological samples is crucial but time-consuming. To automate the segmentation, supervised learning approaches have been used, but they require expensive and error-prone label preparation. In this work, we investigated unsupervised and semisupervised approaches for fine-grained shale and developed a semi-supervised learning model, SU-Net, which demonstrated higher accuracy and faster training than existing models.
GEOENERGY SCIENCE AND ENGINEERING
(2023)
Article
Energy & Fuels
Xiaoming Zhang, Ren Wang, Wanzhong Shi, Qinhong Hu, Xiaofeng Xu, Zhiguo Shu, Yang Yang, Qian Feng
Summary: Descriptions, field emission-scanning electron microscopy and geochemical analyses were used to study the developmental properties and controlling factors of natural fractures in the Wufeng-Longmaxi Shales. The study revealed the presence of non-tectonic bedding fractures, tectonic fractures, and micro-fractures. The extent of fracture development is influenced by external structural and internal lithofacies factors. The research provides a model for the development of natural fractures and their impact on shale gas accumulation.
GEOENERGY SCIENCE AND ENGINEERING
(2023)
Article
Energy & Fuels
Shuo Qin, Ren Wang, Wanzhong Shi, Wei Zhang, Rong Qi, Kai Liu, Xiaofeng Xu, Mehdi Ostadhassan
Summary: This study investigates the morphology, development factors, and implications of intragranular fractures in the tight sandstones of the He-1 Member in Shihezi Formation in Hangjinqi area. It reveals that the development of fractures is influenced by factors such as effective pressure, mineral composition, and grain size, and that reservoirs developed in braided bar and channel show better petrophysical properties with more fractures.
GEOENERGY SCIENCE AND ENGINEERING
(2023)
Article
Energy & Fuels
Yuzuo Liu, Wanzhong Shi, Kun Yuan, Ren Wang, Xiaofeng Xu, Xiaoming Zhang, Luheng Bai, Qian Feng, Kurt O. Konhauser
Summary: This study investigates the organic matter accumulation mechanism in the Nabiao Formation of the Youjiang Basin, South China. The results show that the Chotec Event is more conducive to organic matter enrichment than the Kacak Event. Furthermore, oceanic upwelling and dysoxic conditions play important roles in the accumulation of organic matter.
GEOENERGY SCIENCE AND ENGINEERING
(2024)
