Capillary Pressure and Wettability Behavior of CO2 Sequestration in Coal at Elevated Pressures
- Willem-Jan Plug (Horizon Energy Partners) | Saikat Mazumder (Shell International B.V.) | Johannes Bruining (Delft U. of Technology)
- Document ID
- Society of Petroleum Engineers
- SPE Journal
- Publication Date
- December 2008
- Document Type
- Journal Paper
- 455 - 464
- 2008. Society of Petroleum Engineers
- 5.8.9 HP/HT reservoirs, 5.10.1 CO2 Capture and Sequestration, 5.8.3 Coal Seam Gas, 5.3.1 Flow in Porous Media, 5.4.2 Gas Injection Methods, 5.8.8 Gas-condensate reservoirs, 6.5.2 Water use, produced water discharge and disposal, 5.6.2 Core Analysis, 4.3.4 Scale, 5.5 Reservoir Simulation, 1.2.3 Rock properties, 4.1.2 Separation and Treating, 5.1 Reservoir Characterisation, 4.6 Natural Gas, 5.5.11 Formation Testing (e.g., Wireline, LWD), 5.4 Enhanced Recovery, 5.5.8 History Matching, 2.2.2 Perforating, 2.4.3 Sand/Solids Control, 5.3.2 Multiphase Flow, 4.1.5 Processing Equipment
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Enhanced coalbed-methane (ECBM) recovery combines recovery of methane (CH4) from coal seams with storage of carbon dioxide (CO2). The efficiency of ECBM recovery depends on the CO2 transfer rate between the macrocleats, via the microcleats to the coal matrix. Diffusive transport of CO2 in the small cleats is enhanced when the coal is CO2-wet. Indeed, for water-wet conditions, the small fracture system is filled with water and the rate of CO2 sorption and CH4 desorption is affected by slow diffusion of CO2. This work investigates the wetting behavior of coal using capillary pressures between CO2 and water, measured continuously as a function of water saturation at in-situ conditions. To facilitate the interpretation of the coal measurements, we also obtain capillary pressure curves for unconsolidated-sand samples. For medium- and high-rank coal, the primary drainage capillary pressure curves show a water-wet behavior. Secondary forced-imbibition experiments show that the medium-rank coal becomes CO2-wet as the CO2 pressure increases. High-rank coal is CO2-wet during primary imbibition. The imbibition behavior is in agreement with contact-angle measurements. Hence, we conclude that imbibition tests provide the practically relevant data to evaluate the wetting properties of coal.
Geological sequestration (Orr 2004) of CO2 is one of the viable methods to stabilize the concentration of greenhouse gases in the atmosphere and to satisfy the Kyoto protocol. The main storage options are depleted oil and gas reservoirs (Shtepani 2006; Pawar et al. 2004), deep (saline) aquifers (Kumar et al. 2005; Pruess et al. 2003; Pruess 2004), and unmineable coalbeds (Reeves 2001). Laboratory studies and recent pilot field tests (Mavor et al. 2004; Pagnier et al. 2005) demonstrate that CO2 injection has the potential to enhance CH4 production from coal seams. This technology can be used to sequester large volumes of CO2, thereby reducing emissions of industrial CO2 as a greenhouse gas (Plug 2007). The efficiency of CO2 sequestration in coal seams strongly depends on the coal type, the pressure and temperature conditions of the reservoir (Siemons et al. 2006a, 2006b), and the interfacial interactions of the coal/gas/water system (Gutierrez-Rodriguez et al. 1984; Gutierrez-Rodriguez and Aplan 1984; Orumwense 2001; Keller 1987). It can be expected that in highly fractured coal systems the wetting behavior positively influences the efficiency of ECBM recovery. It is generally accepted that the coal structure consists of the macrocleat and fracture system (>50 nm) and the coal matrix (<50 nm). The macrofracture system is initially filled with water and provides the conduits where the mass flow is dominated by Darcy flow. The coal matrix can be subdivided in mesocleats (from 2 to 50 nm), microcleats (from 0.8 to 2 nm), and the micropores (<0.8 nm). The matrix system is relatively impermeable, and the mass transfer is dominated by diffusion. After a dewatering stage, CO2 is injected and flows through the larger cleats of the coal. Subsequently, CO2 is transported through the smaller cleats and is sorbed in the matrix blocks (Siemons et al. 2006a). Depending on the wettability of coal, we can distinguish the following gas exchange mechanisms:
- The coal is water-wet, and CO2 and CH4 diffuse in the water-filled cleats.
- The coal is CO2-wet or gas-wet, and countercurrent capillary diffusion can take place.
- The coal is gas-wet, and binary diffusion of CO2 and CH4 occurs.
Capillary diffusion finds its origin in capillary pressure
(Pc ) effects, where Pc is defined as the pressure difference between the nonaqueous and aqueous phase. The storage rate for CO2 is much smaller if the microcleat system is water-wet. This is because of the small CO2 molecular-diffusion coefficient (D CO2 ˜ 2 x 10-9 m2/s). For CO2-wet conditions, a faster and more efficient sorption rate is expected and the molecular diffusion is much larger (i.e., D CO2 ˜ 1.7 x 10-7 m2/s at 100 bar) (Bird et al. 1960). Therefore, we assert that the wettability of coal is important for ECBM recovery applications. For this reason, we have undertaken an experimental study to investigate the wetting properties of two different coal types under reservoir conditions, measuring the capillary pressure between CO2 and water. The dissolution properties of CO2 in water (Wiebe and Gaddy 1940), the interfacial tension between water and CO2 (Chun and Wilkinson 1995), and the CO2 sorption (Siemons et al. 2003) play important roles in the interpretation of capillary pressure experiments. The CO2, will sorb on the coal and will cause a swelling-induced permeability decrease (Mazumder et al. 2006). The higher the pressure, the more CO2 can be sorbed and the more the coal swells (Reucroft and Sethuraman 1987). The largest amount of sorption-induced swelling in intact coal is approximately 4%. It is found that the swelling for ground coal is much higher than intact coal and has been reported to be in the order of 15-20%. The swelling causes a porosity reduction, thus the water saturation decreases.
In the Background section, relevant literature about the wettability of coal and the capillary pressure is summarized. The Experimental Design section describes the experimental setup we have developed to measure the capillary pressure as a function of the CO2 pressure. Furthermore, we describe the sample preparation and experimental procedure. In the Results and Discussion section, the experimental results are presented and discussed. We end with Conclusions.
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Anderson, W.G. 1986. Wettability Literature Survey--Part2: Wettability Measurement. JPT 38 (11): 1246-1262.SPE-13933-PA. doi: 10.2118/13933-PA.
Anderson, W.G. 1987. Wettability Literature Survey--Part4: Effects of Wettability on Capillary Pressure. JPT 39 (10):1283-1300. SPE-15271-PA. doi: 10.2118/15271-PA.
Bird, R.B., Steward, W.E., and Lightfoot, E.N. 1960. TransportPhenomena. New York City: John Wiley and Sons.
Chi, S.M., Morsi, B.I., Klinzing, G.E., and Chiang, S.H. 1988. Study of interfacial properties inthe liquid CO2-water-coal system. Energy Fuels 2(2): 141-145. doi:10.1021/ef00008a007.
Christoffersen, K.R. and Whitson, C.H. 1995. Gas/Oil Capillary Pressure of Chalkat Elevated Pressures. SPEFE 10 (3): 153-159. SPE-26673-PA.doi: 10.2118/26673-PA.
Chun, B.-S. and Wilkinson, G.T. 1995. Interfacial tension inhigh-pressure carbon dioxide mixtures. Ind. Eng. Chem. Res.34 (12): 4371-4377. doi:10.1021/ie00039a029.
Dabbous, M.K., Reznik, A.A., Mody, B.G., Fulton, P.F., and Taber, J.J. 1976.Gas-Water Capillary Pressure inCoal at Various Overburden Pressures. SPEJ 16 (5): 261-268;Trans., AIME, 261. SPE-5348-PA. doi: 10.2118/5348-PA.
Gutierrez-Rodriguez, J.A. and Aplan, F.F. 1984. The effect of oxygen onthe hydrophobicity and floatability of coal. Colloids and Surfaces12: 27-51. doi:10.1016/0166-6622(84)80087-6.
Gutierrez-Rodriguez, J.A., Purcell, R.J. Jr., and Aplan, F.F. 1984. Estimating thehydrophobicity of coal. Colloids and Surfaces 12: 1.doi:10.1016/0166-6622(84)80086-4.
Hassanizadeh, S.M., Celia, M.A., and Dahle, H.K. 2002. Dynamic effect in thecapillary pressure-saturation relationship and its impacts on unsaturated flow.Vadose Zone J. 1 (1): 38-57.
Hirasaki, G.J. 1991. Wettability:Fundamentals and Surface Forces. SPEFE 6 (2): 217-226;Trans., AIME, 291. SPE-17367-PA. doi: 10.2118/17367-PA.
Jennings, J.R. Jr., McGregor, D.S, and Morse, R.A. 1988. Simultaneous Determination ofCapillary Pressure and Relative Permeability by Automatic History Matching.SPEFE 3 (2): 322-328. SPE-14418-PA. doi: 10.2118/14418-PA.
Keller, D.V. Jr. 1987. The contact angle ofwater on coal. Colloids and Surfaces 22 (1): 21-35.doi:10.1016/0166-6622(87)80003-3.
Kokkedee, J.A. 1994. Simultaneous Determination ofCapillary Pressure and Relative Permeability of a Displaced Phase. PaperSPE 28827 presented at the European Petroleum Conference, London, 25-27October. doi: 10.2118/28827-MS.
Kumar, A., Ozah, R., Noh, M.K., Pope, G.A., Bryant, S., Sepehrnoori, K., andLake, L.W. 2005. ReservoirSimulation of CO2 Storage in Deep Saline Aquifers. SPEJ 10(3): 336-348. SPE-89343-PA. doi: 10.2118/89343-PA.
Longeron, D., Hammervold, W.L., and Skjaeveland, S.M. 1995. Water-Oil Capillary Pressure andWettability Measurements Using Micropore Membrane Technique. Paper SPE30006 presented at the International Meeting on Petroleum Engineering, Beijing,14-17 November. doi: 10.2118/30006-MS.
Mavor, M.J., Gunter, W.D., and Robinson, J.R. 2004. Alberta Multiwell Micro-Pilot Testingfor CBM Properties, Enhanced Methane Recovery and CO2 Storage Potential.Paper SPE 90256 presented at the SPE Annual Technical Conference andExhibition, Houston, 26-29 September. doi: 10.2118/90256-MS.
Mazumder, S., Karnik, A., and Wolf, K.H. 2006. Swelling of Coal in Response to CO2Sequestration for ECBM and its Effect on Fracture Permeability. SPEJ11 (3): 390-398. SPE-97754-PA. doi: 10.2118/97754-PA.
Mazumder, S., Plug, W.-J., and Bruining, J. 2003. Capillary Pressure and WettabilityBehavior of Coal-Water-Carbon Dioxide System. Paper SPE 84339 presented atthe SPE Annual Technical Conference and Exhibition, Denver, 5-8 October. doi:10.2118/84339-MS.
Murata, T. 1981. Wettability of coalestimated from the contact angle. Fuel 60 (8): 744-746. doi:10.1016/0016-2361(81)90230-1.
Newsham, K.E., Rushing, J.A., Lasswell, P.M., Cox, J.C., and Blasingame,T.A. 2004. Comparative Study ofLaboratory Techniques for Measuring Capillary Pressures in Tight Gas Sands.Paper SPE 89866 presented at the SPE Annual Technical Conference andExhibition, Houston, 26-29 September. doi: 10.2118/89866-MS.
Orr, F.M. Jr. 2004. Storage ofCarbon Dioxide in Geologic Formations. JPT 56 (9): 90-97.SPE-88842-MS. doi: 10.2118/88842-MS.
Orumwense, F.F.O. 2001. Wettability ofcoal--A comparative study. Scandinavian J. of Metallurgy 30(4): 204-211. doi: 10.1034/j.1600-0692.2001.300402.x.
Pagnier, H.J.M., van Bergen, F., Kreft, E., van der Meer, L.G.H., andSimmelink, H.J. 2005. FieldExperiment of ECBM-CO2 in the Upper Silesian Basin of Poland (RECOPOL).Paper SPE 94079 presented at the SPE Europec/EAGE Annual Conference, Madrid,Spain, 13-16 June. doi: 10.2118/94079-MS.
Pawar, R.J., Warpinski, N.R., Benson, R.D., Grigg, R.B., Krumhansl, J.L.,and Stubbs, B.A. 2004. GeologicSequestration of CO2 in a Depleted Oil Reservoir: An Overview of a FieldDemonstration Project. Paper SPE 90936 presented at the SPE AnnualTechnical Conference and Exhibition, Houston, 26-29 September. doi:10.2118/90936-MS.
Plug W.-J. 2007. Measurements of capillary pressure and electricpermittivity of gas-water systems in porous media at elevated pressures;Application to geological storage of CO2 in aquifers and wettingbehavior in coal. PhD thesis, Delft University of Technology, Delft, TheNetherlands.
Plug, W.J. and Bruining, J. 2007. Capillary pressure forthe sand-CO2-water system under various pressure conditions.Application to CO2 sequestration. Advances in WaterResources 30 (11): 2339-2353.doi:10.1016/j.advwatres.2007.05.010.
Plug, W.J., Mazumder, S., Bruining, J., Siemons, N., and Wolf, K.H. 2006.Capillary pressure and wettability behavior of the coal-water-carbon dioxidesystem at high pressures. Paper 606 presented at the International CBMSymposium, Tuscaloosa, Alabama, USA, 22-26 May.
Plug, W.J., Slob, E., Bruining, J., and Tirado, L.M.M. 2007. Simultaneous measurement ofhysteresis in capillary pressure and electric permittivity for multiphase flowthrough porous media. Geophysics 72 (3): A41.doi:10.1190/1.2714684.
Pruess, K. 2004. NumericalSimulation of CO2 Leakage From a Geologic Disposal Reservoir, IncludingTransitions From Super- to Subcritical Conditions, and Boiling of LiquidCO2. SPEJ 9 (2): 237-248. SPE-86098-PA. doi:10.2118/86098-PA.
Pruess, K., Xu, T., Apps, J., and Garcia, J. 2003. Numerical Modeling of AquiferDisposal of CO2. SPEJ 8 (1): 49-60. SPE-83695-PA. doi:10.2118/83695-PA.
Reeves, S.R. 2001. GeologicalSequestration of CO2 in Deep, Unmineable Coalbeds: An Integrated Research andCommerical-Scale Field Demonstration Project. Paper SPE 71749 presented atthe SPE Annual Technical Conference and Exhibition, New Orleans, 30 September-3October. doi: 10.2118/71749-MS.
Reucroft, P.J. and Sethuraman, A.R. 1987. Effect of pressure on carbondioxide induced coal swelling. Energy Fuels 1 (1): 72-75.doi:10.1021/ef00001a013.
Shtepani, E. 2006. CO2Sequestration in Depleted Gas/Condensate Reservoirs. Paper SPE 102284presented at the SPE Annual Technical Conference and Exhibition, San Antonio,Texas, USA, 24-27 September. doi: 10.2118/102284-MS.
Siemons N., Busch, A., Bruining, H., Krooss, B., and Gensterblum, Y. 2003.Assessing the Kinetics andCapacity of Gas Adsorption in Coals by a Combined Adsorption/DiffusionMethod. Paper SPE 84340 presented at the SPE Annual Technical Conferenceand Exhibition, Denver, 5-8 October. doi: 10.2118/84340-MS.
Siemons N., Bruining, H., Wolf, K.-H., and Plug, W.-J. 2006a. PressureDependence of the CO2 Contact Angle on Bituminous Coal andSemi-Anthracite in Water. Paper 0605 presented at the International CBMSymposium, Tuscaloosa, Alabama, USA, 22-26 May.
Siemons N. et al. 2006b. Pressure dependence of thecontact angle in a CO2 - H2O -coal system. J.Coll. Int. Sci. 297 (2): 755-761.doi:10.1016/j.jcis.2005.11.047.
Wiebe, R. and Gaddy, V.L. 1940. The solubility of carbon dioxidein water at various temperatures from 12 to 40°C and at pressures to 500atmospheres. Critical phenomena. J. Am. Chem. Soc. 62 (4):815-817. doi:10.1021/ja01861a033.
Wildenschild, D., Hopmans, J., and Simunek, J. 2001. Flow rate dependence ofsoil hydraulic characteristics. Soil Sci. Soc. Am. J. 65 (1):35-48.