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Application of the thermoporoelasticity model in numerical modelling of underground coal gasification influence on the surrounding medium

Anna Uciechowska-Grakowicz
Anna Uciechowska-Grakowicz
 oraz 
Tomasz Strzelecki
Tomasz Strzelecki
   | 30 cze 2021
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Article Category: Original Study
Data publikacji: 30 cze 2021
Zakres stron: 116 - 134
Otrzymano: 26 sie 2020
Przyjęty: 14 lut 2021
DOI: https://doi.org/10.2478/sgem-2021-0004
Słowa kluczowe
© 2021 Anna Uciechowska-Grakowicz et al., published by Sciendo
This work is licensed under the Creative Commons Attribution 4.0 International License.

Figure 1

Schematic of the UCG process (linked vertical wells method), with water entering from the surrounding rocks [6].
Schematic of the UCG process (linked vertical wells method), with water entering from the surrounding rocks [6].

Figure 2

Generated finite element mesh determining the model's geometry (non-uniform scale, aspect ratio 5:1). Geological layers: 1. sandstone, 2. clayey pebble, 3. clay, 4. lignite (UCG generator is located in the middle of this layer), 5. clay, 6. clayey sand, 7. clay, 8. silty clay.
Generated finite element mesh determining the model's geometry (non-uniform scale, aspect ratio 5:1). Geological layers: 1. sandstone, 2. clayey pebble, 3. clay, 4. lignite (UCG generator is located in the middle of this layer), 5. clay, 6. clayey sand, 7. clay, 8. silty clay.

Figure 3

Cross-section (y = 750 m) through the area of interest – position of coal gasification generator marked at the centre.
Cross-section (y = 750 m) through the area of interest – position of coal gasification generator marked at the centre.

Figure 4

Main boundary conditions on cross-section, (non-uniform scale, aspect ratio5:1). Geological layers: 1. sandstone, 2. clayey pebble, 3. clay, 4. lignite (UCG generator is located in this layer), 5. clay, 6. clayey sand, 7. clay, 8. silty clay.
Main boundary conditions on cross-section, (non-uniform scale, aspect ratio5:1). Geological layers: 1. sandstone, 2. clayey pebble, 3. clay, 4. lignite (UCG generator is located in this layer), 5. clay, 6. clayey sand, 7. clay, 8. silty clay.

Figure 5

Evolution of temperature at selected points of the gasified area.
Evolution of temperature at selected points of the gasified area.

Figure 6

Evolution of temperature changes around the coal gasification generator over time: a) start, b) 0.5 year, c) 1 year, d) 1.5 year, e) 2 year, f) 2.5 year.
Evolution of temperature changes around the coal gasification generator over time: a) start, b) 0.5 year, c) 1 year, d) 1.5 year, e) 2 year, f) 2.5 year.

Figure 7

Water vapour presence in cross-section at times a) start, b) 0.5 year, c) 1 year, d) 1.5 year, e) 2 years f) 2.5 year.
Water vapour presence in cross-section at times a) start, b) 0.5 year, c) 1 year, d) 1.5 year, e) 2 years f) 2.5 year.

Figure 8

Spatial situation of area of water vapour presence at time t = 1 year.
Spatial situation of area of water vapour presence at time t = 1 year.

Figure 9

Distribution of displacements (m) in the cross-section at y = 750 m at times a) 1 month, b) 0.5 year, c) 1 year, d)2 years.
Distribution of displacements (m) in the cross-section at y = 750 m at times a) 1 month, b) 0.5 year, c) 1 year, d)2 years.

Figure 10

a) Charts of displacements (m) over time, b) 3D vector field of displacements near the generator at t = start, c) displacement vector field near the generator at time t = 2 years.
a) Charts of displacements (m) over time, b) 3D vector field of displacements near the generator at t = start, c) displacement vector field near the generator at time t = 2 years.

Figure 11

Vector field of horizontal displacements (m): a–d) on the background of the temperature in cross-section z = 51.5: a) 1 month, b) 1 year c) 2 year, d) 3 year e) horizontal displacements over time (A and B).
Vector field of horizontal displacements (m): a–d) on the background of the temperature in cross-section z = 51.5: a) 1 month, b) 1 year c) 2 year, d) 3 year e) horizontal displacements over time (A and B).

Figure 13

Vector field of water conduction rate (m/s) on the background of the permeability (m/s) in cross-section y = 750 m at t = 1.5 year.
Vector field of water conduction rate (m/s) on the background of the permeability (m/s) in cross-section y = 750 m at t = 1.5 year.

Figure 14

Heat transfer coefficient (W/m/K) at t = 1 year: cross-section y = 750 m, close-up of gasification area.
Heat transfer coefficient (W/m/K) at t = 1 year: cross-section y = 750 m, close-up of gasification area.

Figure 15

A) temperature (°C) after 6 years when thermal parameters of water vapour were accepted in volume, where phase transition occurred, b) temperature in case, where no phase transition in the pores was modelled c) time course of temperature in both cases at point x = 71,5 m, y = 75,0 m, z = 63 m.
A) temperature (°C) after 6 years when thermal parameters of water vapour were accepted in volume, where phase transition occurred, b) temperature in case, where no phase transition in the pores was modelled c) time course of temperature in both cases at point x = 71,5 m, y = 75,0 m, z = 63 m.

Material parameter values of individual geological layers.

Layer Roof min [m] Roof max [m] f [−] N [Pa] A [Pa] α [−] ρs [Mg/m3] K [m/s] cv [J/kg/K] λ [W/m/K]
Sandstone 4.7 10.9 0.15 2.31E+09 3.46E+09 1.16E-05 2.6 5.00E-07 1100 3.1
Clayey pebble 25.2 32.7 0.28 3.90E+06 2.40E+07 6.00E-06 2.53 3.00E-06 639 2.5
Clay 50 50 0.31 1.32E+07 6.91E+07 5.80E-06 2.38 3.00E-08 566 2.1
Coal* 53 53 0.2 5.80E+08 8.70E+08 5.00E-06 1.21 5.00E-09 1250 0.5
Clay 57.2 69.8 0.4 1.28E+06 9.42E+06 5.90E-06 2.62 6.00E-08 481 2.9
Clayey sand 80.5 95 0.32 1.30E+06 9.00E+06 6.00E-06 2.49 1.20E-06 889 3.5
Clay 125.9 149.9 0.37 2.50E+06 1.85E+07 6.10E-06 2.71 7.00E-08 514 1.4
Silty clay 166.1 184 0.28 3.30E+06 1.50E+07 6.00E-06 2.66 5.00E-08 612 1.9

Thermal parameters of individual pore fluids and medium.

Thermal expansion coefficient 1) [1/K] Initial heat transfer coefficient [W/m/K] specific heat [J/kg/K]
Water 69·10−6 0.6 4150
Water vapour 1/T 16.2·10−3 1970
Medium - λ = (1 − f) λs + fλf cν = (ρ1 cνs + ρ2 cνf) / ρ
eISSN:
2083-831X
Język:
Angielski
Częstotliwość wydawania:
4 razy w roku
Dziedziny czasopisma:
Geosciences, other, Materials Sciences, Composites, Porous Materials, Physics, Mechanics and Fluid Dynamics
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