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1 – 10 of 69Yijun Hou, Dongdong Wang and Guoqi Dong
The purpose of this paper is to take the early Permian no.6 coal seam in Jungar coalfield of North China as an example, this paper studied the net primary productivity (NPP) level…
Abstract
Purpose
The purpose of this paper is to take the early Permian no.6 coal seam in Jungar coalfield of North China as an example, this paper studied the net primary productivity (NPP) level of the early Permian peatland and its relationship with the atmospheric environment at that time, analyzed the influence of the atmospheric environment, and discussed its control factors.
Design/methodology/approach
First, geophysical logging signals were used for a spectrum analysis to obtain the Milankovitch cycle parameters in the no. 6 coal seam, including the eccentricity (95 ka); obliquity (35.6 ka); and precession (21.2 ka). These were then used to calculate the accumulation rate of the residual carbon in the no. 6 coal seam, which was determined to be between 49.44 and 50.57 gC/(m2 · a). The carbon loss could be calculated according to the density and residual carbon content of the no. 6 coal seam. Then, the total carbon accumulation rate of the peatland was further derived as being between 64.91 and 66.40 gC/(m2 · a). Also, the NPP of the peatland was determined to be between 129.82 and 132.8 gC/(m2 · a).
Finding
The result showed that the NPP of the early Permian peatland area was lower than that of the Holocene at the same latitude, and also lower than that of the later Permian of South China.
Originality/value
This study’s comprehensive analysis indicated that the temperature and humidity conditions, along with the oxygen and carbon dioxide levels in the atmosphere, were the main control factors of the NPP of the early Permian peatland. Also, wildfires were found to play a role.
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The world’s oil majors were slow to recognise the rise of the shale industry, which was driven by smaller independent producers. Now the majors are following the path forged by…
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DOI: 10.1108/OXAN-DB219975
ISSN: 2633-304X
Keywords
Geographic
Topical
Wen Yang, Sherong Hu and Shimin Ma
The purpose of this paper is to find the relationship of palaeontology, palaeobotany and coal thickness of Taiyuan Formation during Late Carboniferous – Early Permian Period in…
Abstract
Purpose
The purpose of this paper is to find the relationship of palaeontology, palaeobotany and coal thickness of Taiyuan Formation during Late Carboniferous – Early Permian Period in Shanxi Province.
Design/methodology/approach
This paper selects three regions, namely, Baode, Xishan and Lingchuan, to analyse the distribution characteristics of palaeontology, palaeobotany and variation of coal thickness.
Findings
It was found that in a certain period of geological history, palaeontology and palaeobotany play a dominant role in shaping of a coal-bearing basin. Coal seam thickness changes largely from the northwest to the southeast, gradually thinning in Taiyuan Formation.
Originality/value
Palaeontology and palaeobotany play a dominant role in the shaping of a coal-bearing basin.
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Oklahoma’s STACK and SCOOP shale play.
Details
DOI: 10.1108/OXAN-DB225971
ISSN: 2633-304X
Keywords
Geographic
Topical
Wei Guo, Honglin Liu and Chaoli Lan
Based on core description, gas logging and laboratory analysis, this paper aims to study the controlling effect of the types of shale sedimentary microfacies in coal formations…
Abstract
Purpose
Based on core description, gas logging and laboratory analysis, this paper aims to study the controlling effect of the types of shale sedimentary microfacies in coal formations over shale reservoirs using the example of Shanxi formation in Northern Ordos Basin.
Design/methodology/approach
According to core observation, the authors selected typical samples of rock types for thin section analysis to determine the micro features and compositions of rocks.
Findings
By using core observation, we found that fine lithology in Shanxi formation included major shale, carbonaceous shale, partially carbonaceous shale, partially silty shale and silty shale with colors of gray, dark gray, black and/or gray. Shanxi Formation shale are deposited in plant-rich and plant-poor swamps, interdistributary depressions of delta plains, interfluvial depressions of meandering rivers as well as microfacies environment of natural levees and the distal crevasse splay.
Originality/value
Currently, the research on the shale gas in Shanxi Formation in the Ordos Basin is still in its infancy. There is yet no research on the fine-grained partition of the sedimentary facies in coal accumulation environment of Shanxi formation and the controlling effect of sedimentary microfacies over shale reservoirs.
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Chao Jin, LangTao Liu, GuoQiang Hao and Kuo Cao
Sedimentary facies type of the Shanxi Formation in northeastern Ordos Basin is an ongoing debate. Based on field measurements, sample collection and identification, and laboratory…
Abstract
Sedimentary facies type of the Shanxi Formation in northeastern Ordos Basin is an ongoing debate. Based on field measurements, sample collection and identification, and laboratory analysis, we systematically evaluated the sedimentary characteristics of the sandstone bodies of Shanxi Formation of Chengjiazhuang section in Liulin. Analysis included identifying sample composition, grain size, texture, sedimentary structure and spatial distribution. We came to the conclusion that the sedimentary environment of Shanxi Formation is deltaic. This deltaic environment included deltaic front and deltaic plain. It can be further divided into five sedimentary microfacies: subfluvial distributary channel, subfluvial distributary interchannel, distributary channel, levee, and peat bog. And lastly, the evolution of sedimentary environment of Shanxi Formation is discussed.
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The US shale industry has emerged from the worst of the crude price downturn battered, but also leaner and more efficient. Many shale producers are eager to return to growth…
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DOI: 10.1108/OXAN-DB216056
ISSN: 2633-304X
Keywords
Geographic
Topical
The current oil industry downturn has not led to the same sort of industry mega-mergers that previous down cycles have produced. However, as oil prices stabilise at 45-50 dollars…
Details
DOI: 10.1108/OXAN-DB212242
ISSN: 2633-304X
Keywords
Geographic
Topical
The US shale oil industry has mounted a comeback over the past six months. After a deep recession brought on by plunging oil prices starting in mid-2014, the sector is growing…
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DOI: 10.1108/OXAN-DB221222
ISSN: 2633-304X
Keywords
Geographic
Topical
Yongliang Wang, Jin Huang and Guocheng Wang
This study aims to analyse the deep resource mining that causes high in situ stress, and the disturbance of tunnelling and mining which may induce large stress concentration…
Abstract
Purpose
This study aims to analyse the deep resource mining that causes high in situ stress, and the disturbance of tunnelling and mining which may induce large stress concentration, plastic deformation and rock strata compression deformation. The depth of deep resources, excavation rate and multilayered heterogeneity are critical factors of excavation disturbance in deep rock. However, at present, there are few engineering practices used in deep resource mining, and it is difficult to analyse the high in situ stress and dynamic three-dimensional (3D) excavation process in laboratory experiments. As a result, an understanding of the behaviours and mechanisms of the dynamic evolution of the stress field and plastic zone in deep tunnelling and mining surrounding rock is still lacking.
Design/methodology/approach
This study introduced a 3D engineering-scale finite element model and analysed the scheme involved the elastoplastic constitutive and element deletion techniques, while considering the influence of the deep rock mass of the roadway excavation, coal seam mining-induced stress, plastic zone in the process of mining disturbance of the in situ stress state, excavation rate and layered rock mass properties at the depths of 500 m, 1,500 m and 2,500 m of several typical coal seams, and the tunnelling and excavation rates of 0.5 m/step, 1 m/step and 2 m/step. An engineering-scale numerical model of the layered rock and soil body in an actual mining area were also established.
Findings
The simulation results of the surrounding rock stress field, dynamic evolution and maximum value change of the plastic zone, large deformation and settlement of the layered rock mass are obtained. The numerical results indicate that the process of mining can be accelerated with the increase in the tunnelling and excavation rate, but the vertical concentrated stress induced by the surrounding rock intensifies with the increase in the excavation rate, which becomes a crucial factor affecting the instability of the surrounding rock. The deep rock mass is in the high in situ stress state, and the stress and plastic strain maxima of the surrounding rock induced by the tunnelling and mining processes increase sharply with the excavation depth. In ultra-deep conditions (depth of 2,500 m), the maximum vertical stress is quickly reached by the conventional tunnelling and mining process. Compared with the deep homogeneous rock mass model, the multilayered heterogeneous rock mass produces higher mining-induced stress and plastic strain in each layer during the entire process of tunnelling and mining, and each layer presents a squeeze and dislocation deformation.
Originality/value
The results of this study can provide a valuable reference for the dynamic evolution of stress and plastic deformation in roadway tunnelling and coal seam mining to investigate the mechanisms of in situ stress at typical depths, excavation rates, stress concentrations, plastic deformations and compression behaviours of multilayered heterogeneity.
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