scholarly journals Soviet experience of underground coal gasification focusing on surface subsidence

2015 ◽  
Vol 16 (10) ◽  
pp. 839-850 ◽  
Author(s):  
Yury Derbin ◽  
James Walker ◽  
Dariusz Wanatowski ◽  
Alec Marshall
Keyword(s):  
Coal Gasification ◽  
Surface Subsidence ◽  
Underground Coal Gasification ◽  
Soviet Experience

scholarly journals Subsidence and heat propagation modeling on the underground coal gasification (Case study at Muara Enim Formation, South Sumatera)

2020 ◽  
Vol 23 (2) ◽  
pp. 83-98
Author(s):  
Zulfahmi Zulfahmi ◽  
◽  
Ildrem Syafri ◽  
Abdurrokhim Abdurrokhim ◽  
Ridho Wattimena ◽  
...  
Keyword(s):  
Coal Gasification ◽  
Mechanical Characteristics ◽  
Heat Propagation ◽  
Surface Subsidence ◽  
Underground Coal Gasification ◽  
Propagation Modeling ◽  
External Conditions ◽  
Cap Rock ◽  
Physical And Mechanical Characteristics

One of the important issues to study underground coal gasification (UCG) is the prediction of surface subsidence. Several parameters that influence these conditions are the thickness of cap rock, the physical and mechanical characteristics, the structure condition, the minerals composition of the rock, and external conditions. This study had been carried out simulation and modeling to determine the level of surface subsidence risk and the effect of high temperatures due to the activities. The modeling results show that the thickness of the rock above the UCG coal seam greatly affects the surface subsidence. The depth is more than 200 m and found that the SF value is 1.59 which indicates UCG reactor depth of ≥ 200 m is safe from the risk of subsidence. From the characteristic aspect of the cap rock, the claystone types which not contain kaolinite minerals are more prone to collapse than those of contain kaolinite minerals. From this models, the gasifier at 150 m depth was estimated that there will be a decline of -7.23 m, and the minimum subsidence is at 275 m about 0.1 m. The heat propagation modeling results show that at 50 m the temperature is estimated to be 213- 289°C, but if the thickness of the cap rock is > 200 m depth, the temperature is around 29-28°C.

Finite Element Analysis of the Subsidence of Cap Rocks during Underground Coal Gasification Process

2013 ◽  
Vol 859 ◽  
pp. 91-94
Author(s):  
Xiao Xiong Zha ◽  
Hai Yang Wang ◽  
Shan Shan Cheng
Keyword(s):  
Finite Element ◽  
Coal Seam ◽  
Coal Gasification ◽  
Feasibility Studies ◽  
Element Model ◽  
Numerical Results ◽  
Surface Subsidence ◽  
Underground Coal Gasification ◽  
Element Analysis ◽  
Gasification Process

This paper discusses the possible surface subsidence and deformation of the overlying rock during the underground coal gasification (UCG) process, which is an important part of feasibility studies for UCG operations. First coal seam roof movement and surface subsidence in the shallow UCG process were simulated by a finite element model coupled with heat transfer module in COMSOL. Numerical results from this model were compared with and in good agreement to the existing studies. This was followed by the development of model for deeper coal seam cases. The comparison of the numerical results from two models shows that surface uneven settlement in deep underground coal gasification is only 7% of that in shallow underground coal gasification.

Evaluation Method of Surface Subsidence Degree for Underground Coal Gasification without Shaft

2020 ◽  
pp. 1-14
Author(s):  
Huaizhan Li ◽  
Jianfeng Zha ◽  
Guangli Guo ◽  
Hongzhen Zhang ◽  
Youyou Xu ◽  
...  
Keyword(s):  
Coal Gasification ◽  
Evaluation Method ◽  
Surface Subsidence ◽  
Underground Coal Gasification

Thermo-fluid-mechanical numerical simulations of surface subsidence at the site of underground coal gasification

2021 ◽  
pp. qjegh2020-106
Author(s):  
Yury Derbin ◽  
James Walker ◽  
Liphapang Khaba
Keyword(s):  
Coal Combustion ◽  
Coal Gasification ◽  
Complex Geometry ◽  
Surface Subsidence ◽  
Three Dimensions ◽  
Successful Implementation ◽  
Underground Coal Gasification ◽  
Model Surface ◽  
Fluid Analysis ◽  
Upper Aquifer

This work deals with modelling surface subsidence that aims to help industrialize Underground Coal Gasification (UCG). UCG is a long-known, but poorly industrialized method of energy extraction from coal. Risks of surface subsidence and groundwater pollution are two main hurdles that are affecting the potential industrialization of UCG. The particular challenge is the existence of groundwater because of implications to both its pollution and its influence on surface subsidence. Additionally, the coal combustion and the complex geometry of the UCG reactors impacts surface subsidence. To meet these challenges, the thermal and fluid analyses should be included in the model and surface subsidence should be modelled in three dimensions to capture the collapsed shape of the UCG reactor. Based on nature of these challenges and an earlier successful implementation, the commercial software FLAC3D by Itasca with the intrinsic thermal and fluid models is chosen to model surface subsidence.This study discovers that the inclusion of fluid analysis improves the predictions of surface subsidence when compared with measurements at the highly watered Shatsk UCG site. In turn, thermal analysis mildly influences the modelled surface subsidence. The fluid analysis shows that the flow in the upper aquifer influences surface subsidence more greatly than the flow in the lower aquifers. High temperature causes an upward flow in the lower aquifer located above the UCG reactor, but does not change the flow pattern in the upper aquifer. The fluid analysis also reveals that if the UCG reactor is filled with water, the surface subsidence does not occur.

Cold Flow Simulation in Underground Coal Gasification (UCG) Cavities

2014 ◽  
Vol 1 (1) ◽  
pp. 15-24 ◽  
Author(s):  
Dipankar Chatterjee ◽  
◽  
Satish Gupta ◽  
Chebolu Aravind ◽  
Rakesh Roshan
Keyword(s):  
Coal Gasification ◽  
Flow Simulation ◽  
Underground Coal Gasification ◽  
Cold Flow

scholarly journals Changes in properties of tar obtained during underground coal gasification process

2021 ◽  
Author(s):  
Marian Wiatowski ◽  
Roksana Muzyka ◽  
Krzysztof Kapusta ◽  
Maciej Chrubasik
Keyword(s):  
Coal Gasification ◽  
Coal Tar ◽  
Liquid Product ◽  
Coke Oven ◽  
Underground Coal Gasification ◽  
Gasification Process ◽  
Dominant Component ◽  
Process Gas ◽  
High Volatility ◽  
Product Separator

AbstractIn this study, the composition of tars collected during a six-day underground coal gasification (UCG) test at the experimental mine ‘Barbara’ in Poland in 2013 was examined. During the test, tar samples were taken every day from the liquid product separator and analysed by the methods used for testing properties of typical coke oven (coal) tar. The obtained results were compared with each other and with the data for coal tar. As gasification progressed, a decreasing trend in the water content and an increasing trend in the ash content were observed. The tars tested were characterized by large changes in the residue after coking and content of parts insoluble in toluene and by smaller fluctuations in the content of parts insoluble in quinoline. All tested samples were characterized by very high distillation losses, while for samples starting from the third day of gasification, a clear decrease in losses was visible. A chromatographic analysis showed that there were no major differences in composition between the tested tars and that none of the tar had a dominant component such as naphthalene in coal tar. The content of polycyclic aromatic hydrocarbons (PAHs) in UCG tars is several times lower than that in coal tar. No light monoaromatic hydrocarbons (benzene, toluene, ethylbenzene and xylenes—BTEX) were found in the analysed tars, which results from the fact that these compounds, due to their high volatility, did not separate from the process gas in the liquid product separator.

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