報告者 : 藍一平 指導老師 : 蔡龍珆 老師 日期 : 2011/05/26

1. International Journal of Coal Geology , 70, 240–254 CO2 storage and gas diffusivity properties of coals from Sydney Basin, AustraliaA. Saghafi, M. Faiz , D. Roberts 報告者 : 藍一平 指導老師 : 蔡龍珆 老師 日期 :2011/05/26

2. OUTLINE • Introduction • Objectives • Literature Review • Methods • Result and Discussion • Conclusions

3. Introduction

4. extraction well (http://www.zybsh.cn/zs/ytgk/index.htm) Exploration of boreholes involves investigations on factors affecting CO2 storage and injection, in particular the adsorption and diffusivity properties of coal. One particularity of Australian coalfields is the occurrence of large amounts of CO2 in many coal seams.

5. Clayton (1998) listed four sources for CO2 gas in coal seams: CO2 in Sydney Basin coals is mainly derived from magmatic sources as the high CO2 content areas generally have isotopic compositions of δ13C of about −7‰.(Smith and Gould, 1980; Smith et al., 1985)

6. Study Area Hunter Coalfiled Newcastle Coalfiled Western Coalfiled Southern Coalfiled Fig. 1. The major coalfield in Sydney Basin, NSW (http://www.csmenergy.com.au/operations.html) 150 Mt / year of coal Hunter, Newcastle, Western and Southern coalfield Permian-Triassic Medium to high volatile bituminous Open-cut mining

7. Objectives

8. The aim of the present investigation is to characterize Sydney Basin coals according to two parameters (adsorption and diffusivity), particularly for CO2.

9. Literature Review

10. micro-pore • Langmuir equation adsorbed phase In-situ coal contains gas (Langmuir, 1918) • macro-pores free phase

11. Convection Diffusion Sorption (Remner et al., 1984) (Saghafi et al., 1987)

12. Methods

13. Adsorption isotherm • The technique developed to measure adsorption isotherms is based on a gravimetric method. (Saghafi, 2003) Fig. 2. Schematic diagram of gravimetric adsorption measurement apparatus.

14. Measurement method for gas diffusivity • Fick's equation : P1 = P2 C1,1 > C2,1 Fig. 3. Schematic diagram of measurement apparatus for gas diffusivity in coal.

15. Result and Discussion

16. Coal sampling and measuring conditions Contact metamorphosed

17. Adsorption isotherm measurements (1) Fig. 4. Measured adsorbed volume versus Langmuir estimated volume for CO2 adsorption. Fig. 5. Relative error (r) in using a Langmuir type equation for determining CO2 adsorption for all coals studied.

18. Adsorption isotherm measurements (2) Fig. 6. CO2 Langmuir volume VL for the Sydney Basin coals in relation to volatile matter content (VM). no clear relationship Fig. 8. CO2 adsorption capacity of the Sydney Basin coals according to the rank Fig. 7. Langmuir pressure (PL) in relation to volatile matter content.

19. Adsorption isotherm measurements (3) C0=30.1 m3/t h0=400 m a=0.56 Fig. 9. CO2 storage capacity of the Sydney Basin coals at in-situ pressure

20. Diffusivity and porosity measurements no clear relationship Fig. 10. CO2 diffusivity and coal porosity according to depth. Fig. 11. CO2 diffusivity and porosity according to volatile matter content

21. Comparison of properties of main seam gases CO2/CH4 : 1.8 CO2/N2 : 5.9 Fig. 12. Adsorption of pure CO2, CH4 and N2 on coal (coal17).

22. Conclusions

23. The highest adsorptive capacity corresponds to the deepest, highest rank coal, the lowest corresponds to a shallower coal but not necessarily the lowest rank coal. For these samples, no clear relation between the diffusivity and the depth or rank of coals. The CO2 storage capacity is about twice that of CH4 and six timesthat of N2. The diffusivity of CO2 in coal is about twice that of CH4.

24. Thanks for Your Attention!