1. ESTIMATION OF VOID VOLUME BY DIFFERENT GASES AND ITS
IMPACT ON
GAS ADSORPTION IN COAL
Submitted by :
AMIT KUMAR SOREN
219MN1586
Under the guidance of :
Prof. SANTANU BHOWMIK
DEPARTMENT OF MINING ENGINEERING
NATIONAL INSTITUTE OF TECHNOLOGY, ROURKELA
2. 1. INTRODUCTION
2. LITERATURE REVIEW
3. OBJECTIVE
4. METHODOLOGY
5. RESULTS & DISCUSSIONS
6. CONCLUSIONS
7. SCOPE FOR FUTURE WORK
OUTLINE OF PRESENTATION
3. 1. INTRODUCTION
• In CBM reservoir mainly methane is formed from vegetative matter and trapped into the coal during the coalification process.
• CBM reservoir is considered as a dual-porosity, single-permeability structure. (Warren and Root, 1963)
• Pores of the coal are mainly classified into three sizes : macropores (>500 Å), mesopores (20 to 500 Å), and micropores (8 to 20 Å). (Mahajan and
Walker, 1978)
• The coal natural fracture system is mainly of three types, face cleats, butt cleats and the tertiary cleats.
Figure 1. (a) : A simplified model of coalbed Figure 1. (b) Micro view of coalbed structure
structure and gas in coal. (Lin, 2014) and gas in coal. (Lin, 2014)
1
4. 1.1 Statement of the problem
The current research was planned to work in the following key areas:
• How gases like CH4 or CO2 affects the void volume calibration ?
• What variation in void volume with temperature-pressure?
• How void volume is affected by gas properties ?(Compressibility factor or free gas density)
• How much deviation in adsorption capacity for different gases like CH4 and CO2 at different temperature?
2
5. Author and Year Study area
Warren and Root, 1963 Behavior of a permeable medium which affects the flow capacity within the pore volume.
Mahajan and Walker, 1978 Surface areas, densities and pore volume distributions of coals undergo significant changes upon heat treatment.
GRI, 1996 Fundamental properties of CBM reservoir different from conventional gas reservoir.
Clarkson and Bustin, 1999 The characterization of pore volume distribution for coals of varying (organic and mineral) composition.
Laxminarayana and Crosdale, 1999 Factors affecting the sorption properties of Indian coals.
Ozdemir et al., 2003 Volumetric effects when an adsorbate alters the structure of an adsorbent.
Busch et al., 2003 Adsorption/Desorption of CO2 and CH4 on coals of similar maceral composition. (0.25% to 1.68% Ro%)
Mavor et al., 2004 Error analysis performed to evaluate the accuracy of storage capacity.
Romanov et al., 2006 Errors associated with the volumetric effects.
Dutta et al., 2008 Modification of conventional adsorption equation to account the uncertainties in void volume.
Sakurovs et al., 2008 Potential sources of error and their impact in measured sorption.
Dutta et al., 2011 The influence of rank and macerals on the sorption of CO2 and CH4.
Lin and Kovscek, 2014 Sorption induced volumetric change of the coal.
2. LITERATURE REVIEW
2.1 Earlier work related to gas adsorption according to year
3
6. 2.2 Summary of the literature review
Based on the literature review presented in the earlier, the following observation are made:
The void volume may not be always constant due to presence of adsorbed phase.
At higher temperatures adsorption of gas molecules decreases.
After reaching a maximum storage capacity of gas there is no effect of pressure.
The type of the adsorbate gas and its properties (like compressibility factor, density) can vary with isotherm temperature and pressure.
Changes in the kinetic diameter among helium (28 nm), CH4 (38 nm) and CO2 (33nm) may create the “different” void volume for CH4/CO2.
4
7. 3. OBJECTIVE
Following objectives are chosen for the present study:
A. Study the fundamentals of CBM reservoir transport and production.
B. Performing void volume calibration for adsorption isotherm test.
C. Estimate the void volume changes and its effect on gas adsorption capacity.
5
8. Figure 2 : Schematic diagram of the gas adsorption
experimental setup. (Dutta et al., 2008)
4. METHODOLOGY
4.1 Sample collection and preparation (ASTM Designation : D3172 – 13, 2013)
(30-50 g, -100 to +150 mesh size )
4.2 Isotherm test (Dutta et al., 2008)
• 4.2.1 Performing of leak test
• 4.2.2 Estimation of the empty volumes of the reference and sample cells
• 4.2.3 Estimation of the void volume in the sample cell
• 4.2.4 Adsorption isotherm measurement
4.3 Calibration of reference cell and sample cell by CH4 and CO2
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9. 5. RESULTS AND DISCUSSIONS
5.1 CH4 and CO2 absolute adsorption isotherms
0.0
0.2
0.4
0.6
0.8
0 2000 4000 6000 8000
GAS_STORAGE_CAPACITY,
mmol/g
SAMPLE_CELL_PRESSURE, kPa
ABS_ADS_CH4
0.0
0.2
0.4
0.6
0.8
0 2000 4000 6000 8000
GAS_STORAGE_CAPACITY,
mmol/g
SAMPLE_CELL_PRESSURE, kPa
ABS_ADS_CH4
0.0
0.6
1.2
1.8
2.4
3.0
0 2000 4000 6000 8000
GAS_STORAGE_CAPACITY,
mmol/g
SAMPLE_CELL_PRESSURE, kpa
ABS_ADS_CO2 0.0
0.6
1.2
1.8
0 2000 4000 6000 8000
GAS_STORAGE_CAPACITY,
mmol/g
SAMPLE_CELL_PRESSURE, kpa
ABS_ADS_CO2
(a) (b)
Figure 3: Gas storage capacity for CH4 at (a) Narayankuri seam R III at 30ºC (b) R-16 bottom at 40ºC.
(a) (b)
Figure 4: Gas storage capacity for CO2 (a) Narayankuri seam R III at 30ºC (b) Kargali seam at 40ºC.
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10. 5.2 Compressibility factor of He, CH4 and CO2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 1500 3000 4500 6000
COMPRESSIBILITY
FACTOR,
Z
SAMPLE CELL PRESSURE, kPa
He_30C
CH4_30C
CO2_30C
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 1500 3000 4500 6000
COMPRESSIBILITY
FACTOR,
Z
SAMPLE CELL PRESSURE, kPa
He_40C
CH4_40C
CO2_40C
(a) (b)
Figure 5: Compressibility factor of Helium, CH4 and CO2 at (a) 30ºC and (b) 40ºC.
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11. 5.3 Variation in the free gas phase density of He, CH4 and CO2
0
2
4
6
8
10
0 1500 3000 4500 6000
DENSITY,
kg/m3
SAMPLE CELL PRESSURE, kPa
He_40C
He_30C
0
10
20
30
40
50
0 1500 3000 4500 6000
DENSITY,
kg/m3
SAMPLE CELL PRESSURE, kPa
CH4_40C
CH4_30C
0
40
80
120
160
200
0 1500 3000 4500 6000
DENSITY,
kg/m3
SAMPLE CELL PRESSURE, kPa
CO2_40C
CO2_30C
(a) (b) (c)
Figure 6: Density of (a) Helium, (b) CH4 and (c) CO2 at 30°C and 40°C
0
40
80
120
160
200
0 1300 2600 3900 5200 6500
DENSITY,
kg/m3
SAMPLE CELL PRESSURE, kPa
He_30C
CH4_30C
CO2_30C
0
40
80
120
160
0 1300 2600 3900 5200 6500
DENSITY,
kg/m3
SAMPLE CELL PRESSURE, kPa
He_40C
CH4_40C
CO2_40C
(a) (b)
Figure 7: Comparison of density for Helium, CH4 and CO2 at (a) 30°C and (b) 40°C.
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16. 6. CONCLUSIONS
i. The compressibility factor of gases vary with change in pressure and temperature.
ii. The Density is also playing a very crucial role in void volume estimation, because there is not much difference in the free gas density of Helium and
CH4, but for CO2 it is not the case.
iii. It is observed that the void volume calculated by CH4 or CO2 is little bit less as calculated with Helium calibration data.
iv. With these void volume changes it can be seen that the absolute adsorption for the CH4 and CO2 calibrated results are increased.
v. The maximum deviations for CH4/CO2-calibrated isotherms at 30°C and 40°C, changes is easily visible.
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17. 7. SCOPE FOR FUTURE WORK
The proposed works for future are as follows:
1.Correlation of deviations with coal properties and coal rank.
2.Detailed uncertainty analysis for errors in the sorption isotherm test.
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18. REFERENCES
• American Society for Testing and Materials (ASTM)., 2013. Standard Practice for Proximate Analysis of Coal and Coke, ASTM Designation: D3172 –
13.
• Busch, A., Gensterblum, Y., Krooss, B.M., 2003. Methane and CO2 sorption and desorption measurements on dry Argonne premium coals: pure
components and mixtures. International Journal of Coal Geology. 55, pp. 205–224.
• Clarkson, C.R., Bustin, R.M., 1999. The effect of pore structure and gas pressure upon the transport properties of coal: a laboratory and modeling
study: 1. Isotherms pore volume distribution. Fuel 78, pp. 1333–1344.
• Dutta, P., Harpalani, S., Prusty, B., 2008. Modeling of CO2 sorption on coal. Fuel 87, pp. 2023–2036.
• Dutta, P., Bhowmik S., Das, S., 2011. Methane and carbon dioxide sorption on a set of coals from India. International Journal of Coal Geology. 85, pp.
289–299.
• Dutta, P., Chatterjee, A, Bhowmik., S., 2020. Isotherm characteristics and impact of the governing factors on supercritical CO2 adsorption properties of
coals, Journal of CO₂ Utilization Vol. 39, 101150.
• Gas Research Institute (GRI), 1996. A guide to Coalbed Methane Reservoir Engineering, published by Gas Research Institute, Chicago, Illinois, USA,
GRI Reference No. GRI- 94/0397, 30 pages.
• Lin, W., and Kovscek A.R., 2014. Gas Sorption and the Consequent Volumetric and Permeability Change of Coal I: Experimental Transp Porous
Media. 105, pp. 371–389.
• Laxminarayana, C., Crosdale, P.J., 1999. Role of coal type and rank on methane sorption characteristics of Bowen Basin, Australia coals. International
Journal of Coal Geology. 40, pp. 309–325.
19. • Mahajan, O.P. and Walker, P.L., Jr., 1978. Porosity of Coal and Coal Products, Research Report, The Pennsylvania State University PSU-TR-7.
• Mavor, M.J., Hartman, C., and Pratt, T.J., 2004. Uncertainty in Sorption Isotherm Measurements,, Proceedings International Coalbed Methane
Symposium, University of Alabama, Tuscaloosa. paper 411, pp. 1-14.
• Ozdemir, E., Morsi, B.I., Schroeder, K., 2003. Importance of volume effects to adsorption isotherms of carbon dioxide on coals. Langmuir 19, pp.
9764–9773.
• Romanov V.N, Goodman A.L, Larsen J.W., 2006 Errors in CO2 adsorption measurements caused by coal swelling. Energy and Fuels. 20,pp. 415–
416.
• Sakurovs, R., Day, S., Weir, S., 2008. Causes and consequences of errors in determining sorption capacity of coals for carbon dioxide at high
pressure, International Journal of Coal Geology, COGEL-01525; No of Pages 7.
• Warren, J.E. and Root, P.J., 1963. The Behaviour of Naturally Fractured Reservoirs, Society of Petroleum Engineers Journal. Volume 3, pp. 245-255.
