Article
Energy & Fuels
Lei-lei Yang, Xinwei Li, Qingong Zhuo, Zhichao Yu, Yulong Yang, Keyu Liu
Summary: This study examines the influence of gypsum-salt rock on the development of carbonate reservoirs in the Qaidam Basin, China. The research shows that the concentration of Ca2+ in the fluid controls the dissolution and precipitation of carbonate minerals in the reservoir, while sufficient Mg2+ is necessary for dolomitization. The precipitation of anhydrite decreases with increasing temperature, indicating that it is more easily formed at lower temperatures. The dissolution of calcium-containing minerals in the overlying gypsum-salt rock can lead to mineral precipitation in the underlying reservoir, reducing its quality.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Energy & Fuels
Fei Yang, Fang Wang, Jiangmin Du, Shuang Yang, Rongqin Wen
Summary: To investigate the evolution mechanism of nanoscale pore within lacustrine organic-rich shales, artificially matured shale samples from the Ordos Basin were treated using hydrous pyrolysis experiment, and various experiments were conducted to analyze the nanopore evolution. The results showed that pore sizes ranged from 1.1 to 500 nm, and the overall porosity increased and then decreased. Different types of pores were observed at different temperatures, and the cumulative specific surface areas increased at 400 degrees C due to the dehydration and transformation reactions of clay minerals. This study provides insights for shale gas exploration in lacustrine shales with different thermal maturities.
JOURNAL OF PETROLEUM EXPLORATION AND PRODUCTION TECHNOLOGY
(2023)
Article
Geosciences, Multidisciplinary
Wenqiang Gao, Shixiang Li, Peng Song, Hongbo Xue, Suping Ma, Yanqing Xia, Xiaofeng Ma, Zhiwei Liu
Summary: The predominance of tricyclic terpanes over hopanes was observed for the first time in the lacustrine rock extracts of the Upper Yanchang Formation collected from Well CYX in the Qingcheng area, Ordos Basin, China. The distributions of terpanes, steranes, as well as n-alkanes vary significantly in these thermally mature rock extracts, however, are closely correlated in each sample. The observation of the enhanced presence of tricyclic terpanes in the current study may suggest that the hydrocarbon-generating intensity and petroleum expulsion efficiency of source rocks in the Qingcheng area are higher than that of other regions in the basin.
MARINE AND PETROLEUM GEOLOGY
(2023)
Article
Geosciences, Multidisciplinary
Bojiang Fan
Summary: The Triassic Yanchang Formation in the central Ordos Basin, China, has shown great potential as a shale oil/gas play, with six wells currently producing more than 5 tons of oil per day. This study aimed to understand the controlling factors for organic matter enrichment in the Chang-7 shale and the environmental conditions under which it was deposited. Comprehensive lithological, organic geochemical, and element analyses revealed that the Chang-7 shale is primarily composed of massive to laminated shales and was deposited in a shallow to semi-deep lake environment. The shale has a high organic carbon content and is in a moderate thermal evolutionary stage, making it a moderate to high-quality source rock. The organic matter in the shale has a mixed source, including in situ production and terrestrial input from rivers.
NATURAL RESOURCES RESEARCH
(2022)
Article
Energy & Fuels
Shutong Li, Yang Wang, Ximeng Wang, Ruiliang Guo
Summary: The pore system and gas adsorption characteristics of mudstones in the Ordos Basin were studied. The results show that the studied mudstones are mainly siliceous rocks with intergranular pores and less developed organic matter pores. Micropores and mesopores are the main pore types, with abundant organic matter pores. The presence of rigid minerals can inhibit the compaction of intergranular pores. Organic matter, clays, and rigid minerals have a limited positive effect on gas adsorption capacity. Methane is mainly stored in micropores.
Article
Geosciences, Multidisciplinary
Matthew A. Hemenway, Stephen E. Kaczmarek
Summary: Portable Energy-Dispersive X-Ray Fluorescence spectrometry (PXRF) is used to identify elemental variations in fine-grained siliciclastics. In this study, over 9000 PXRF analyses from nine drill cores are used to document variations in the carbonate mudstones of the Silurian A-1 Carbonate in the Michigan Basin. The data show that variations in the minor, non-carbonate sediment fraction within the A-1 Carbonate are regionally correlative, suggesting that siliciclastic and evaporite deposition responded in tandem to basin-wide controls on sedimentation.
MARINE AND PETROLEUM GEOLOGY
(2021)
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
Energy & Fuels
Jia-Qi Yang, Jun-Tao Zhang, Zhi-Liang He, Tao Zhang
Summary: Reconstructing paleoenvironments is crucial for understanding the development and evolution of carbonate reservoirs. The Middle Ordovician Period is significant for its greenhouse conditions and biological evolution. By analyzing the carbonate rocks in the Dingbei area of the Ordos Basin, the paleoenvironment was reconstructed, revealing high seawater paleotemperature, suboxic-anoxic paleoredox conditions, and high seawater paleosalinity. The presence of planktonic organisms led to an increase in total organic carbon, providing a supplementary source for natural gas. The dissolution of gypsum and its residual presence further contributed to the preservation of natural gas. This study provides valuable data and a theoretical basis for natural gas exploration.
Article
Engineering, Marine
Yiqing Wang, Yaohui Xu, Junping Huang, Jianglong Shi, Heng Zhao, Qingtao Wang, Qiang Meng
Summary: The study performed thermal simulation experiments on Nordic carbonates from the Ordovician Majiagou Formation to analyze the hydrocarbon production characteristics and geochemical characteristics. The results showed that the Nordic carbonates have different hydrocarbon production characteristics from the mud shale of the same parent material type, with a large amount of H2S production. The carbon isotope composition is controlled by thermal evolution, and the addition of calcium sulphate significantly affects the methane content but increases the yield of heavy hydrocarbon gases.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2023)
Article
Chemistry, Multidisciplinary
Yining Li, Wenhui Liu, Peng Liu, Houyong Luo, Xiaofeng Wang, Dongdong Zhang, Yilin Yuan
Summary: The Middle Ordovician Majiagou marine carbonates in the Ordos Basin, China, are important natural gas exploration targets and potential gas source rocks. Sea level changes regulated the conditions for the enrichment of organic matter, with the third member of the Majiagou Formation showing higher preservation conditions compared to the fourth member. Gypsum plays a potential role in the blooming of special organisms and the preservation of organic matter.
ACS EARTH AND SPACE CHEMISTRY
(2021)
Article
Geosciences, Multidisciplinary
Tianshu Zhang, Suyun Hu, Qingyun Bu, Bin Bai, Shizhen Tao, Yanyan Chen, Zhejun Pan, Senhu Lin, Zhenglian Pang, Wanglin Xu, Miao Yuan, Jianwei Fan, Yuanshi Sun, Xuan Feng
Summary: By analyzing core samples and well logging data, this study proposes a novel method based on parasequence division to predict organic matter enrichment in Chang 7 Shale. It identifies certain shale facies as more favorable for shale oil exploration, providing insights for determining target areas and enhancing inter-well prediction for deep-water shales.
MARINE AND PETROLEUM GEOLOGY
(2021)
Article
Geosciences, Multidisciplinary
Lianhua Hou, Zhenglian Pang, Xia Luo, Senhu Lin
Summary: This study investigated the influence of gravity flows on the development of black shale in lacustrine settings using various analysis methods. The results showed that the formation of black shale is greatly affected by gravity flows, leading to different depositional settings and lithofacies characteristics. Proxies of paleo-water depth, settling rate, productivity, redox conditions, and clastic influx were found to play important roles in the deposition of these lithofacies.
MARINE AND PETROLEUM GEOLOGY
(2023)
Article
Geology
Yang Li, Renchao Yang
Summary: The division of geological time and the evaluation of Earth's climate changes are important for understanding geological processes and Earth's evolutionary history. However, the Triassic period remains a weak link in the geological timescale. This study presents new evidence to refine the astronomical scale of the Triassic by analyzing sedimentary deposits in the southern Ordos Basin. The findings suggest that the Chang 7 Member was deposited during the Ladinian and Carnian, which contributes to a better understanding of the Triassic period.
Article
Geosciences, Multidisciplinary
Guilherme Bozetti, Xiangbo Li, Zhanlong Yang, Huaqing Liu, Junping Huang, Zhiyong Li, Jingping Xu
Summary: Deep-lacustrine systems have been less studied compared to marine systems due to the scarcity of large and continuous outcrops globally. This study examines outcrops and cores from the Ordos Basin in China, revealing the presence of deep-lacustrine slope channels and levee deposits composed of interbedded sandstones and mudstones. The re-interpretation of sandstone-prone deposits in the Yanchang Formation provides insights into the architectural elements in intracratonic lacustrine basins, with implications for hydrocarbon exploration and production.
JOURNAL OF ASIAN EARTH SCIENCES
(2023)
Article
Energy & Fuels
Yubin Bai, Jingzhou Zhao, Yanjie Huang, Zaihua Han
Summary: Based on the geochemical analysis of the Chang 7 source rock, it is revealed that the Chang 6 crude oil in the AY oil province is primarily formed from the local Chang 7 source rock, rather than from long-distance migration from the basin center.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)