Article
Geochemistry & Geophysics
Xiaoxia Peng, Guobin Li, Xin Cheng, Ling Guo
Summary: This study conducted a comprehensive analysis of pore types and karstification forms in the fifth member of the Majiagou Formation in the Ordos Basin. The research identified interparticle pores, separate-vuggy pores, and touching-vuggy pores in the formation. The dominant forms of karstification were syngenetic karstification, weathering crust karstification, and burial karstification. The study emphasized the influence of factors such as sea level fluctuations, exposure duration, and acidic formation water on the observed patterns of karstification. The study also highlighted the importance of structural and composite fractures in oil and gas migration and reservoir development.
Article
Energy & Fuels
Bo Jiu, Wenhui Huang, Nana Mu, Yuan Li
Summary: Continuous advancements in oil and gas exploration technology have shifted the focus towards ultradeep reservoirs due to increasing demand for resources. This study examines the carbonate karst reservoirs in the Ordovician Ma5 Member in the southeastern Ordos Basin, analyzing development characteristics, types, and influencing factors of paleokarst reservoirs. Petrology and geochemistry indicate three types of karstification processes, controlled by freshwater and thermochemical sulfate reduction, resulting in diverse dissolution pores and fractures in the reservoirs.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2021)
Article
Geochemistry & Geophysics
Lihong Liu, Chunlian Wang, Zhili Du, Jianghua Gong
Summary: The pore cementation of anhydrite is crucial in determining reservoir properties, with different mineral fillings in different regions. Negative isotopic values of calcite filling suggest an influence of thermochemical sulfate reduction.
Article
Energy & Fuels
Wei Liubin, Zhao Junxing, Su Zhongtang, Wei Xinshan, Ren Junfeng, Huang Zhengliang, Wu Chunying
Summary: Analyzing outcrop profiles, drilling cores, cast thin sections, etc., this study systematically analyzed the types, microfacies combinations, and distribution patterns of microbial carbonates in the middle assemblage of the mid-eastern Ordos Basin during the Ordovician period. The distribution of microbial carbonates is influenced by sequence cycles, sedimentary facies changes, and ancient landforms, and they are mainly found in the tidal flat environment during specific depositional stages in different sub-members of the Ordovician middle assemblage.
PETROLEUM EXPLORATION AND DEVELOPMENT
(2021)
Article
Energy & Fuels
Zhou Jingao, Yu Zhou, Wu Dongxu, Ren Junfeng, Zhang Daofeng, Wang Shaoyi, Yin Chen, Liu Yuxin
Summary: By studying two types of dolomite reservoirs in the Ordos Basin, we found that different diagenetic processes and fillings led to changes in reservoir porosity, which is of great significance for the restoration of porosity evolution in other basins or series of strata.
PETROLEUM EXPLORATION AND DEVELOPMENT
(2022)
Article
Energy & Fuels
Baobao Wang, Xiucheng Tan, Wenjie Su, Wei Yan, Di Xiao, Mushi Guo, Shoukang Zhong, Yuqing Xu, Mengying Yang
Summary: This study investigates the nature and types of dolomite reservoirs in the Ordos Basin, China, and delves into the reservoir characteristics, diagenetic history, and fluid-related mechanisms that influence dolomite reservoir development and preservation in gypsum-carbonate rock assemblages. Results suggest that dolomite reservoirs in the studied area have undergone complex multistage development, primarily in the depositional to penecontemporaneous stages, providing new insights into the origins of deeply buried dolomite reservoirs in carbonate-evaporite successions.
ENERGY EXPLORATION & EXPLOITATION
(2022)
Article
Geochemistry & Geophysics
Haiyan Wu, Ting Liang, Chao Gao, Yanjun Wu, Hongxia Cao, Jun Yu, Fenfei Bai, Jianbo Sun, Keyong Li, Yanqin Guo
Summary: A study was conducted on the Yan'an gas field to examine the natural gas reserves, diagenetic evolution, and different diagenesis environments. The results showed the lithology of the reservoir and the filling materials, as well as the carbon and oxygen isotope values and Sr-87/Sr-86 values. The stratigraphic development indicated a cyclical trend, and the fluid inclusions revealed the sources of fluids in the sedimentation and diagenesis process.
Article
Energy & Fuels
Ji-Jun Li, Zi-Wei Song, Chun -Lin Zhang, Shuang-Fang Lu, Mei-Jun Dong, Shu-Ning Zhang, Jun Jiang
Summary: This study qualitatively investigates the genesis and distribution characteristics of natural gas in the Lower Paleozoic Ordovician strata in the Ordos Basin, China. The results show that the contribution of Upper and Lower Paleozoic source rocks to the gas source of the Ordovician gas reservoir is controlled by various factors, and the isolation effect of gypsum-salt rocks on the gas source varies.
Article
Geochemistry & Geophysics
Jiaqi Yang, Juntao Zhang, Zhiliang He, Macro Brandano, Chongyang Wu
Summary: This study focused on identifying the types and origins of calcite cements in the Majiagou Formation of the Ordos Basin in China. Petrology, isotopes, and element analysis were conducted, revealing five types of calcite cements, four types of cathodoluminescence intensities, and six types of rare earth element patterns. These findings provide valuable insights for predicting reservoir quality in limestone formations during oil and gas exploration.
Article
Geosciences, Multidisciplinary
Wenchao Dou, Luofu Liu, Langbo Jia, Zhengjian Xu, Mengyao Wang, Chongjiao Du
Summary: Several fractal models based on MIP have been proposed for studying the fractal property of porous materials, but results from different models may not always be consistent. By combining various analysis techniques to study the pore structure and petrophysical properties of tight sandstones, it was found that different MIP fractal models usually give different results.
MARINE AND PETROLEUM GEOLOGY
(2021)
Article
Geosciences, Multidisciplinary
Shuai Shi, Jinxian He, Xiaoli Zhang, Hongchen Wu, Ziqi Yu, Jian Wang, Tiantian Yang, Wei Wang
Summary: Studying the complex pore structures and fractal characteristics of gas shale is important for understanding the mechanism of shale gas accumulation and efficient development. This paper utilizes the fractal theory together with mercury intrusion porosimetry and N-2 adsorption technology to investigate the pore size distribution of shale samples. The results reveal that the most common pore types in the samples are pores between or within clay minerals, micropores and mesopores inside organic matter, and microfractures. The pores of shale samples exhibit fractal geometries, and the fractal dimension correlates positively with the corresponding pore volume.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Geochemistry & Geophysics
Baiqiang Li, Zhenzhen Wu, Taofa Zhou, Bin Chen, Qicong Wang, Xiaoli Zhang
Summary: Diagenetic fluids play a crucial role in modifying reservoirs, affecting petrographic, storage capacity, and geochemical characteristics. This study analyzed two types of dolostone in the Majiagou Formation, revealing different petrological and reservoir properties. The diagenetic fluid properties were characterized through various analytical methods, helping to understand the dolomitization process and predict storage capacity.
Article
Energy & Fuels
Guanping Wang, Qian Zhang, Rukai Zhu, Xuan Tang, Kouqi Liu, Zhijun Jin
Summary: The main pore space in the lacustrine Chang 7 Shale is dominated by macro- and meso-pores, while the pores within organic matter are rarely observed. Quartz promotes the development of macro- and meso-pores, while clay minerals show negative effects on their heterogeneity. A critical maturity point of 0.8% Ro is observed for the change of the pore system, and both fractal dimensions and pore structure proxies show inverse trends before and after this point. These findings contribute to a better understanding of pore system evolution and identification of high-quality reservoirs in lacustrine shales.
GEOENERGY SCIENCE AND ENGINEERING
(2023)
Article
Geosciences, Multidisciplinary
Qibiao Zang, Chenglin Liu, Rizwan Sarwar Awan, Xiya Yang, Zhendong Lu, Guoxiong Li, Yuping Wu, Dehao Feng, Yu Ran
Summary: This research analyzed the characteristics and movable fluid distribution of the Chang 7 reservoir and found significant differences in reservoirs from different areas. Sandstone from the Heshui Block exhibited better physical properties and higher content of movable fluid in submicron pores.
NATURAL RESOURCES RESEARCH
(2022)
Article
Energy & Fuels
HE Haiqing, GUO Xujie, ZHAO Zhenyu, XI Shengli, WANG Jufeng, SONG Wei, REN Junfeng, WU Xingning, BI He
Summary: This study examines the geological conditions and main controlling factors of gas accumulation in the subsalt Ma 4 Member of the Ordovician Majiagou Formation based on extensive drilling, logging, and seismic data. It provides new insights into the control of facies, reservoirs, and accumulations by paleo-uplifts. The study has identified favorable exploration areas and successfully tapped into gas reserves, marking a historic breakthrough in gas exploration in the Ordos Basin.
PETROLEUM EXPLORATION AND DEVELOPMENT
(2022)
Article
Geosciences, Multidisciplinary
Jin Lai, Shichen Liu, Yi Xin, Song Wang, Chengwen Xiao, Qiuqiang Song, Xu Chen, Kefu Yang, Guiwen Wang, Xiujian Ding
Summary: The occurrence and petrology of dolomites, along with their pore systems in the Cambrian of Tarim Basin, China, were documented through the integration of cores, thin sections, and cathodoluminescence analysis. Six types of dolomite were identified, with various pore systems dominating the reservoir types. Fractures were found to enhance reservoir quality in dolostone reservoirs.
Article
Geosciences, Multidisciplinary
Bang Zeng, Meijun Li, Xin Wang, Fangzheng Wang, Chenglin Gong, Jin Lai, Yang Shi
Summary: This study investigates the geochemical features and spatial distribution of effective source rocks in the Fushan Depression using mudstone samples, well-logging curves, and seismic sections. The results show that the good hydrocarbon generation potential source rocks are mainly distributed in different systems tracts and their occurrence is controlled by thermal maturity. The southern slope has fewer hydrocarbon accumulations.
GEOLOGICAL JOURNAL
(2022)
Article
Geosciences, Multidisciplinary
Jin Lai, Xiaojiao Pang, Meng Bao, Bing Wang, Jianan Yin, Guiwen Wang, Xuechun Fan
Summary: Diagenesis plays a significant role in controlling reservoir quality. This study investigated the diagenesis of Paleogene sandstones in the Bohai Bay Basin, China using various testing methods. The results reveal the diagenetic dissolution along bedding planes, with feldspar grains experiencing a high degree of dissolution. Grain size and bedding structure are important factors influencing the dissolution process. These findings contribute to a better understanding of diagenetic models and have implications for reservoir quality prediction and resource assessments.
FRONTIERS OF EARTH SCIENCE
(2022)
Article
Chemistry, Analytical
Ming Guan, Xiaoping Liu, Zhijun Jin, Jin Lai, Biao Sun, Panpan Zhang, Kefei Chen
Summary: This study investigates the variation of pore structure heterogeneity during thermal maturation in shale samples. It combines multifractal theory with nitrogen adsorption-desorption tests to determine the governing factors. The study finds that the increasing thermal maturity leads to changes in pore structure heterogeneity, influenced by the volume difference between different types of pores.
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
(2022)
Article
Geosciences, Multidisciplinary
Ming Guan, Xiaoping Liu, Zhijun Jin, Jin Lai, Jie Liu, Biao Sun, Tian Liu, Zuxian Hua, Wen Xu, Honglin Shu, Gaocheng Wang, Mengcai Liu, Yufeng Luo
Summary: The heterogeneity and lack of proper parameters in lacustrine shale oil occurrences hinder the assessment of shale oil reserves. This study characterized shale oil content using petroleum compositional characteristics and determined its spatial occurrence. The controlling factors of shale oil content were also discussed. This work has implications for optimizing exploration targets and evaluating resource potential.
MARINE AND PETROLEUM GEOLOGY
(2022)
Article
Geosciences, Multidisciplinary
Xiaojiao Pang, Guiwen Wang, Lichun Kuang, Hongbin Li, Yidi Zhao, Dong Li, Xin Zhao, Songtao Wu, Zhou Feng, Jin Lai
Summary: The study focuses on the relationship between pore structure and oil movability in fine-grained sedimentary rocks, utilizing various analysis methods such as thin sections, mercury injection capillary pressure (MICP), and nuclear magnetic resonance (NMR). A quantitative evaluation model of movable oil saturation was established based on the findings, improving the understanding of tight/shale oil enrichment in this type of sedimentary rocks.
MARINE AND PETROLEUM GEOLOGY
(2022)
Review
Geochemistry & Geophysics
Jin Lai, Guiwen Wang, Qixuan Fan, Xiaojiao Pang, Hongbin Li, Fei Zhao, Yuhang Li, Xin Zhao, Yidi Zhao, Yuyue Huang, Meng Bao, Ziqiang Qin, Qiqi Wang
Summary: This review aims to bridge the gap between well-log evaluation and unconventional hydrocarbon resources by characterizing various properties using petrophysical well logs. Advanced well-log series are used to evaluate unconventional oil and gas, including NMR log, image logs, array acoustic logs, ECS and LithoScanner logs. The relationships between the properties are revealed, and the geological and engineering sweet spots are optimized to support decision-making in exploration and exploitation.
SURVEYS IN GEOPHYSICS
(2022)
Article
Geosciences, Multidisciplinary
Xiaojiao Pang, Guiwen Wang, Lichun Kuang, Fei Zhao, Chaoliu Li, Chongyang Wang, Mei Zhang, Jin Lai
Summary: Lamellation fractures have significant effects on reservoir quality and hydraulic fracturing engineering in shale oil reservoirs. They are parallel along weak bedding planes and favor the connectivity of pores and throats, leading to high reservoir quality in shale oil reservoirs.
MARINE AND PETROLEUM GEOLOGY
(2023)
Article
Geochemistry & Geophysics
Jin Lai, Guiwen Wang, Qixuan Fan, Fei Zhao, Xin Zhao, Yuhang Li, Yidi Zhao, Xiaojiao Pang
Summary: This paper discusses the scientific interpretation of geophysical well log data, highlighting typical misunderstandings and proposing countermeasures. Factors affecting data acquisition and the applications of well logs in structural geology, sedimentary geology, and petroleum geology are summarized. The review also provides insights into solving geological issues using well logs based on published papers and personal experiences. This study is highly important for petrophysicists and geologists in interpreting geophysical well log data and addressing geological problems.
SURVEYS IN GEOPHYSICS
(2023)
Article
Energy & Fuels
Jin Lai, Xiaojiao Pang, Xin Zhao, Yidi Zhao, Guiwen Wang, Yuyue Huang, Hongbin Li, Yuhang Li
Summary: The method and theoretical system of well logging geology have been widely used but there are frequent misunderstandings due to the different response sensitivity of different well logging series to geological information and the mismatching between geophysical properties of multiple well logs and geological genesis of rocks. It is crucial to analyze typical misunderstanding cases and explore scientific ideas and countermeasures.
NATURAL GAS INDUSTRY B
(2023)
Article
Geosciences, Multidisciplinary
Jin Lai, Fei Zhao, Mei Zhang, Tianyu Bai, Yuyue Huang, Dong Li, Guiwen Wang, Ziqiang Qin
Summary: Research shows that fracture porosity can become very high in ultra-deep burial conditions, especially in situations with low stress difference and high dissolution.
GEOSCIENCE FRONTIERS
(2023)
Article
Energy & Fuels
Xiao-Jiao Pang, Gui-Wen Wang, Li-Chun Kuang, Jin Lai, Yang Gao, Yi-Di Zhao, Hong-Bin Li, Song Wang, Meng Bao, Shi-Chen Liu, Bing-Chang Liu
Summary: Fine-grained sedimentary rocks have gained attention as important reservoirs and source rocks for shale oil and gas. This study focuses on the recognition of centimeter-scale laminae using various methods such as core observation, thin section, X-ray diffraction, conventional log analysis, and image logs. The results provide insights into the prediction of multiscale laminae structure and assist in sweet spots prediction.
Article
Geochemistry & Geophysics
Jin Lai, Dong Li, Yong Ai, Hongkun Liu, Deyang Cai, Kangjun Chen, Yuqiang Xie, Guiwen Wang
Summary: This study comprehensively analyzes the relationship between diagenetic processes and structural pattern, fractures, and in situ stress in the Lower Cretaceous Bashijiqike Formation of the Kuqa Depression. The results reveal the presence of various pore spaces, mechanical compaction, dissolution associated with fractures, and the influence of in situ stress on the formation of intergranular pores and fractures. These findings contribute to predicting reservoir quality and reducing uncertainty in deep natural gas exploration in the Kuqa Depression.
Article
Energy & Fuels
Jin Lai, Bing-Chang Liu, Hong-Bin Li, Xiao-Jiao Pang, Shi-Chen Liu, Meng Bao, Gui-Wen Wang
Summary: This study utilizes core, thin section, conventional, and image log data to investigate the distribution of fractures in the fine-grained sedimentary rocks of the Permian Lucaogou Formation in Jimusar Sag. The results reveal the presence of tectonic inclined fractures, bedding parallel fractures, and abnormal high-pressure fractures. Bedding parallel fractures are abundant but mostly sealed by carbonate minerals and bitumen. These fractures lead to a rapid decrease in resistivity and can be identified on image logs. The distribution of fractures aligns with bedding planes and is influenced by the density of bedding planes. This research provides valuable insights for optimizing sweet spots, improving fracturing designs, and optimizing well spacing in fine-grained sedimentary rocks.
Article
Energy & Fuels
Xiao-Ping Liu, Ming Guan, Zhi-Jun Jin, Zhe Cao, Jin Lai, Lun-Ju Zheng, Wen-Qi Li, Biao Sun, Shan-Yong Chen
Summary: Pyrolysis experiments were conducted on lacustrine organic-rich shale to investigate the impact of hydrocarbon generation on shale pore structure evolution. The results show that thermal evolution controls the transformation of organic matter, characteristics of hydrocarbon products, and changes in pore structure.