Mineralogy and Gas Content of Upper Paleozoic Shanxi and Benxi Shale Formations in the Ordos Basin

2019 ◽  
Vol 33 (2) ◽  
pp. 1061-1068 ◽  
Author(s):  
Fengyang Xiong ◽  
Zhenxue Jiang ◽  
Hexin Huang ◽  
Ming Wen ◽  
Joachim Moortgat
Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Jiaxuan Song ◽  
Hujun Gong ◽  
Jingli Yao ◽  
Huitao Zhao ◽  
Xiaohui Zhao ◽  
...  

The Paleozoic strata are widely distributed in the northwest of the Ordos Basin, and the provenance attributes of the basin sediments during this period are still controversial. In this paper, the detrital zircon LA-MC-ICPMS U-Pb age test was conducted on the drilling core samples of the Shanxi Formation of the Upper Paleozoic in the Otuokeqi area of the Ordos Basin, and the provenance age and the characteristic of the Shanxi formation in the Otuokeqi area in the northwest were discussed. The cathodoluminescence image shows that the detrital zircon has a clear core-edge structure, and most of the cores have clear oscillatory zonings, which suggests that they are magmatic in origin. Zircons have no oscillatory zoning structure that shows the cause of metamorphism. The age of detrital zircon is dominated by Paleoproterozoic and can be divided into four groups, which are 2500~2300 Ma, 2100~1600 Ma, 470~400 Ma, and 360~260 Ma. The first two groups are the specific manifestations of the Precambrian Fuping Movement (2.5 billion years) and the Luliang Movement (1.8 billion years) of the North China Craton. The third and fourth groups of detrital zircons mainly come from Paleozoic magmatic rocks formed by the subduction and collision of the Siberian plate and the North China plate. The ε Hf t value of zircon ranges from -18.36 to 4.33, and the age of the second-order Hf model T DM 2 ranges from 2491 to 1175 Ma. The source rock reflecting the provenance of the sediments comes from the material recycling of the Paleoproterozoic and Mesoproterozoic in the crust, combined with the Meso-Neoproterozoic detrital zircons discovered this time, indicating that the provenance area has experienced Greenwellian orogeny.


2019 ◽  
Vol 110 ◽  
pp. 162-177
Author(s):  
Jun Li ◽  
Jingzhou Zhao ◽  
Xinshan Wei ◽  
Mengna Chen ◽  
Ping Song ◽  
...  

2019 ◽  
Vol 10 (4) ◽  
pp. 1263-1275
Author(s):  
Shanyong Liu ◽  
Gongyang Chen ◽  
Yishan Lou ◽  
Liang Zhu ◽  
Daoyao Ge

AbstractTight gas reservoirs have rich potential resources, which are hot spots in unconventional oil and gas exploration and development. Due to their strong heterogeneity and complex pore structures, the conventional approaches of productivity evaluation always have difficulty in predicting the gas content. This study aims to devise a new method to interpret the productivity of LX Block in the Ordos Basin using the morphological theory and fuzzy mathematics. First, core test results were used to investigate the reservoir quality and physical properties. Then, the change law of gas content was defined by the morphological theory of logging and mud logging curves. Assignments of those factors that affected the final production were provided based on fuzzy mathematics. Finally, the prediction model of productivity was established. The results show that the lower limit of the reservoir thickness in the LX Block is 3.1 m, whereas the porosity and permeability are 5% and 0.15 × 10−3 μm2, respectively. The morphological characteristic of the gas logging curve for those layers with high potential production normally presents a box shape with a high relative number of serration. The reservoir in the studied area can be classified into four categories according to the relationship between the logging curve shape and daily production, and each category is automatically identified. The coincidence rate between the prediction results and the gas test results is 84.1%, which satisfies the demand on the field. The findings have important theoretical and practical significance for screening the location of fracturing spots and predicting the production of tight gas reservoirs.


Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2694
Author(s):  
Guanqun Yang ◽  
Wenhui Huang ◽  
Jianhua Zhong ◽  
Ningliang Sun

The detailed characteristics and formation mechanisms of organic-rich clasts (ORCs) in the Upper Paleozoic tight sandstone in the northeastern margin of the Ordos Basin were analyzed through 818-m-long drilling cores and logging data from 28 wells. In general, compared with soft-sediment clasts documented in other sedimentary environments, organic-rich clasts in coal-bearing tight sandstone have not been adequately investigated in the literature. ORCs are widely developed in various sedimentary environments of coal-bearing sandstone, including fluvial channels, crevasse splays, tidal channels, sand flats, and subaqueous debris flow deposits. In addition to being controlled by the water flow energy and transportation processes, the fragmentation degree and morphology of ORCs are also related to their content of higher plants organic matter. The change in water flow energy during transportation makes the ORCs show obvious mechanical depositional differentiation. Four main types of ORC can be recognized in the deposits: diamictic organic-rich clasts, floating organic-rich clasts, loaded lamellar organic-rich clasts, and thin interlayer organic-rich clasts. The relationship between energy variation and ORCs deposition continuity is rarely studied so far. Based on the different handling processes under the control of water flow energy changes, we propose two ORCs formation mechanisms: the long-term altering of continuous water flow and the short-term water flow acting triggered by sudden events.


2012 ◽  
Vol 3 (6) ◽  
pp. 863-873 ◽  
Author(s):  
Xuan Tang ◽  
Jinchuan Zhang ◽  
Yansheng Shan ◽  
Jinyu Xiong

Sign in / Sign up

Export Citation Format

Share Document