CO2 sequestration into a coal seam project was studied and a numerical model was developed in this paper to simulate the primary and secondary coal bed methane production (CBM/ECBM) and carbon dioxide (CO2) injection. The key geological and reservoir parameters, which are germane to driving enhanced coal bed methane (ECBM) and CO2 sequestration processes, including cleat permeability, cleat porosity, CH4 adsorption time, CO2 adsorption time, CH4 Langmuir isotherm, CO2 Langmuir isotherm, and Palmer and Mansoori parameters, have been analyzed within a reasonable range. The model simulation results showed good matches for both CBM/ECBM production and CO2 injection compared with the field data. The history-matched model was used to estimate the total CO2 sequestration capacity in the field. The model forecast showed that the total CO2 injection capacity in the coal seam could be 22,817 tons, which is in agreement with the initial estimations based on the Langmuir isotherm experiment. Total CO2 injected in the first three years was 2,600 tons, which according to the model has increased methane recovery (due to ECBM) by 6,700？scf/d. 1. Introduction Fossil fuels are currently playing a significant role in the whole world’s energy supply. However, its damage to the environment, especially the CO2 emission resulting in the green house effect, has gotten more and more attention. At present, several geological CO2 sequestration technologies, such as CO2 injection into saline aquifer, CO2-EOR, CO2-ECBM, and so forth, have been studied to minimize the CO2 release into the atmosphere, and these projects have been operating all over the world [1–6]. Studies have shown that unmineable coal seams (seams too deep or too thin to be mined economically) are pretty attractive as one of the promising options for CO2 sequestration because of their large CO2 sequestration capacity, long time CO2 trapping, and extra enhanced coal-bed methane (ECBM) production benefits [1, 7–10]. Field experience with CO2 injection into coal seam is limited, although field tests are planned or are being conducted in the USA, Canada, Poland, Australia, and Japan [3]. However, unlike conventional reservoirs, gas flow in the coal seams can cause the cleat permeability and porosity variation during the injection/production process. Once gas is injected and adsorbed on the coal matrix, the matrix will swell, and correspondently decrease the cleat permeability and porosity [11, 12]. Due to its special features and the nature of gas retention in CBM reservoirs, simulating the production and injection
References
[1]
S. H. Stevens, D. Spector, and P. Riemer, “Enhanced coalbed methane recovery using CO2 injection: worldwide resource and CO2 sequestration potential,” in Proceedings of the 6th International Oil & Gas Conference and Exhibition in China (IOGCEC '98), pp. 489–501, Beijing, China, November 1998.
[2]
J. Ennis-King and L. Paterson, “Engineering aspects of geological sequestration of carbon dioxide,” in Proceedings of the SPE Asia Pacific Oil and Gas Conference and Exhibition, pp. 134–146, Melbourne, Australia, October 2002.
[3]
F. M. Orr Jr., “Storage of carbon dioxide in geologic formations,” Journal of Petroleum Technology, vol. 56, no. 9, pp. 90–97, 2004.
[4]
C. Sinayu？ and F. Gümrah, “Modeling of ECBM recovery from amasra coalbed in Zonguldak Basin, Turkey,” in Proceedings of the Canadian International Petroleum Conference, Alberta, Canada, 2008.
[5]
R. Petrusak, D. Riestenberg, P. Goad et al., “World class CO2 sequestration potential in saline formations, oil and gas fields, coal, and shale: the US southeast regional carbon sequestration partnership has it all,” in Proceedings of the SPE International Conference on CO2 Capture, Storage, and Utilization, pp. 136–153, November 2009.
[6]
C. L. Liner, “Carbon capture and sequestration: overview and offshore aspects,” in Proceedings of the Offshore Technology Conference (OTC '10), pp. 3511–3514, May 2010.
[7]
J. P. Seidle, “Reservoir engineering aspects of CO2 sequestration in coals,” in Proceedings of the SPE/CERI Gas Technology Symposium, Alberta, Canada, 2000.
[8]
H. J. M. Pagnier, F. Van Bergen, E. Kreft, L. G. H. Van Der Meer, and H. J. Simmelink, “Field experiment of ECBM-CO2 in the upper Silesian Basin of Poland (RECOPOL),” in Proceedings of the 67th European Association of Geoscientists and Engineers, EAGE Conference and Exhibition, incorporating SPE (EUROPEC '05), pp. 3013–3015, Madrid, Spain, June 2005.
[9]
G. A. Hernandez, R. O. Bello, D. A. McVay et al., “Evaluation of the technical and economic feasibility of CO2 sequestration and enhanced coalbed-methane recovery in Texas low-rank coals,” in Proceedings of the SPE Gas Technology Symposium: Mature Fields to New Frontiers, pp. 515–530, Alberta, Canada, May 2006.
[10]
G. J. Koperna and D. Riestenberg, “Carbon dioxide enhanced coalbed methane and storage: is there promise?” in Proceedings of the SPE International Conference on CO2 Capture, Storage, and Utilization, pp. 183–195, November 2009.
[11]
J. Q. Shi and S. Durucan, “A model for changes in coalbed permeability during primary and enhanced methane recovery,” SPE Reservoir Evaluation and Engineering, vol. 8, no. 4, pp. 291–299, 2005.
[12]
S. Mazumder and K. H. Wolf, “Differential swelling and permeability change of coal in response to CO2 injection for ECBM,” International Journal of Coal Geology, vol. 74, no. 2, pp. 123–138, 2008.
[13]
L. Dean, “Reservoir engineering for geologists: coalbed methane fundamentals,” Reservoir Issue. 2007, 11.
[14]
Storing CO2 in Unminable Coal Seams, IEA Greenhouse Gas R&D Programme.
[15]
K. Aminian and S. Ameri, “Predicting production performance of CBM reservoirs,” Journal of Natural Gas Science and Engineering, vol. 1, no. 1-2, pp. 25–30, 2009.
[16]
I. Zulkamain, Simulation study of the effect of well spacing, permeability, anisotropy, Palmar and Mansoori model on coalbed methane production. [M.S. thesis], Texas A&M University, 2005.
[17]
I. Palmer and J. Mansoori, “How permeability depends on stress and pore pressure in coalbeds: a new model,” SPE Reservoir Engineering, vol. 1, no. 6, pp. 539–543, 1998.
[18]
“CO2 storage with ECBM study begins in West Virginia,” http://www.carboncapturejournal.com/displaynews.php?NewsID=442.
[19]
D. J. Remner, T. Ertekin, W. Sung, and G. R. King, “Parametric study of the effects of coal seam properties on gas drainage efficiency,” SPE Reservoir Engineering, vol. 1, no. 6, pp. 633–646, 1986.
[20]
A. N. Okeke, Sensitivity analysis of modeling parameters that affect the dual peaking behavior in coalbed methane reservoirs [M.S. thesis], Texas A&M University, 2005.
[21]
Q. P. Huy, K. Sasaki, Y. Sugai, et al., “Numerical simulation of CO2 enhanced coal bed methane recovery for A vietmese coal seam,” JournaL of NoveL Carbon Resource Sciences, vol. 2, pp. 1–7, 2010.
[22]
D. Jasinge and P. G. Ranjith, “Carbon dioxide sequestration in geologic formation with special reference to sequestration in deep coal seams,” in Proceedings of the 45th U.S. Rock Mechanics/Geomechanics Symposium, 2011.
