Methane and carbon dioxide adsorption-diffusion experiments on coal: Upscaling and modeling

Institute of Geology and Geochemistry of Petroleum and Coal, Aachen University (RWTH-Aachen), Aachen, Germany
International Journal of Coal Geology (Impact Factor: 3.38). 12/2004; 60(2):151-168. DOI: 10.1016/j.coal.2004.05.002

ABSTRACT Numerical modelling of the processes of CO2 storage in coal and enhanced coalbed methane (ECBM) production requires information on the kinetics of adsorption and desorption processes. In order to address this issue, the sorption kinetics of CO2 and CH4 were studied on a high volatile bituminous Pennsylvanian (Upper Carboniferous) coal (VRr=0.68%) from the Upper Silesian Basin of Poland in the dry and moisture-equilibrated states. The experiments were conducted on six different grain size fractions, ranging from <0.063 to ∼3 mm at temperatures of 45 and 32 °C, using a volumetric experimental setup. CO2 sorption was consistently faster than CH4 sorption under all experimental conditions. For moist coals, sorption rates of both gases were reduced by a factor of more than 2 with respect to dry coals and the sorption rate was found to be positively correlated with temperature. Generally, adsorption rates decreased with increasing grain size for all experimental conditions.Based on the experimental results, simple bidisperse modelling approaches are proposed for the sorption kinetics of CO2 and CH4 that may be readily implemented into reservoir simulators. These approaches consider the combination of two first-order reactions and provide, in contrast to the unipore model, a perfect fit of the experimental pressure decay curves. The results of this modeling approach show that the experimental data can be interpreted in terms of a fast and a slow sorption process. Half-life sorption times as well as the percentage of sorption capacity attributed to each of the two individual steps have been calculated.Further, it was shown that an upscaling of the experimental and modelling results for CO2 and CH4 can be achieved by performing experiments on different grain size fractions under the same experimental conditions.In addition to the sorption kinetics, sorption isotherms of the samples with different grain size fractions have been related to the variations in ash and maceral composition of the different grain size fractions.

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Available from: Ralf Littke, Sep 27, 2015
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    • "Competitive adsorption behavior of CO 2 and CH 4 in coal seams and carbon nanopore has been reported [2,3,8–18]. Experiments with gas mixtures (CO 2 /CH 4 ) have shown that selective adsorption does not always favor CO 2 and there is clear evidence for preferential adsorption of CH 4 at low pressures [3] [15] [19]. Majewska et al. [19] observed unusually high affinity of bituminous coal for CH 4 over CO 2 at a pressure of 2.6 MPa and a comparable affinity at 4 MPa. "
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    ABSTRACT: Adsorption isotherms of carbon dioxide (CO2) and methane (CH4) provide crucial information for CO2 sequestration and exploitation of coal seam gas. In this work, we focus on the competitive adsorption behavior of CO2 and CH4 in micropores of an intermediate ranked bituminous coal by performing Monte Carlo (MC) simulations at different injection depths from 300 m up to 3280 m with varying injected gas compositions. An extended poromechanical model enables us to relate our simulation results of adsorption to volumetric strain in the coal. Our simulations show that (i) CO2/CH4 adsorption selectivity, defined as the ratio of the mole fractions of the two species in the adsorbed phase relative to the ratio of the mole fractions in the bulk phase, decreases with increasing injection depth for a fixed injected gas composition, (ii) at a given depth, CO2/CH4 adsorption selectivity decreases as the concentration of CO2 in the injected gas increases, (iii) CO2/CH4 adsorption selectivity appears to be a function of pressure and gas composition at a given temperature. The total adsorption increases with increasing concentration of CO2 in the injected gas at constant gas reservoir pressure. The CO2/CH4 adsorption selectivity decreases with increasing bulk CO2 mole fraction after an initial increase at low pressures, (iv) the volumetric strain has a direct correlation with the injected gas composition and increases with the concentration of CO2 in the injected gas. At 370.2 K the largest volumetric strain of 3.6% is predicted at 30 MPa for pure CO2 adsorption.
    Fuel 11/2015; 160:309-317. DOI:10.1016/j.fuel.2015.07.092 · 3.52 Impact Factor
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    • "The potential storage of CO 2 in Italy has never been fully evaluated, but we are convinced that a general Italian survey could be helped by test-sites studies, as ECBM ones, and the two research activities could be parallel (Quattrocchi, 1999; Pizzino et al., 2002; Quattrocchi et al., 2003, 2004 a; Angelone et al., 2004; Miller et al., 2004; Voltattorni et al., 2005). Soon after the first challenging scientific results (Law et al., 2001; Wong et al., 1999, 2001; Mavor et al., 1999; 2002; 2004 a,b; Mac Donald et al., 2003; Gunter et al., 2004) coming from the ECBM scientific Community, strongly busy for the proximal ratification of the Kyoto Agreement (occurred in February 2005), as presented mostly at the GHGT international conferences since 1999 (Green House Gas Control Technologies), ECBM production (Fig. 1) and some challenging pilot-test projects and feasibility studies on ECBM built-up worldwide (Krooss et al., 2002; Busch et al., 2003, 2004; NOVEM, 2001, 2003; Yamaguchi et al., 2004; McIntyre et al., 2004; Reeves, 2004; Carroll and Pashin, 2004; Groshong et al., 2004; Gunter and Chalaturnyk, 2004; Su et al., 2005). "
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    ABSTRACT: An ECBM (Enhanced Coal Bed Methane as evolution of CBM techniques) pre-feasibility study started for the Sulcis Coal Province in December 2004 on the basis of the experience gathered: 1) by INGV, from ongoing and past projects dealing with CO2 geological storage, i.e., Weyburn test-field (Canada) by EOR techniques and from the studies of “CO2 analogues” in Italy; 2) by the coal industry of the Sulcis Province (Sotacarbo S.p.A. & Carbosulcis S.p.A.); 3) by ETH – Zurich, specifically on the coal adsorption properties, and 4) by IES S.r.l. reservoir engineering and gas storage industrial activity. This paper discusses the state of art of the project in the frame of the worldwide ECBM projects as a whole, on the basis of the yet acquired information and available experimental data. Environmental impact considerations are highlighted on the basis of the available Italian legal tools, giving hints for future EU, Italian and new regional legislation and strategies. A new concept of CO2 as “no waste” product in the coal/hydrocarbons provinces for ECBM/EOR exploitation is depicted, defining CO2 a “ natural climatealterant factor”. Geochemical, structural-geology, stratigraphic and reservoir engineering considerations are discussed. The first newly gathered experimental data, including CO2/CH4 coal adsorption capacity data are showed, even if they are preliminary. Starting from the geological and logistical available data, a MapInfo GIS structure was built up, to be jointed later to other EC “CO2 storage” data-GIS as the GETSCO EC project structure. The most important objective of this Phase I is the selection of the best for a ECBM test-pilot site, which will be followed (Phase II) by scaled up site and possibly by a future network (Phase III); these phases are foreseen to be accompanied by the selection of the progressively addedCO2 industrial sources (inserted in the Map-info GIS) to be used within the project economic spreadsheet model. CO2 geological storage in Sardinia is evaluated as a whole, considering the seismotectonic framework and the CO2 industrial sources available or foreseen in the next years. Unpublished Cagliari, Italy
    Clean Coal Technology; 05/2015
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    • "Numerical modelling of the processes of CO 2 storage in coal and enhanced coalbed methane (ECBM) production requires information on the kinetics of adsorption and desorption processes. In order to address this issue, the sorption kinetics of CO 2 and CH 4 were studied on a high volatile bituminous Pennsylvanian (Upper Carboniferous) coal (VRr = 0.68%) from the Upper Silesian Basin of Poland in the dry and moisture-equilibrated states (Busch et al., 2004). "
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    ABSTRACT: Coal gas outbursts (especially CO2) present a high risk in mining of lignite in the Velenje Coal Mine, located in the Velenje Basin in northern Slovenia. A programme of monitoring geochemical parameters was set up to help understand the behaviour of the coalbed gas distribution in advance of the working face using mass spectrometric methods to study its molecular and isotopic compositions and origin. Coalbed gas samples from four different excavation fields (G2/C and K.-130/A from the north and south Preloge mining area and K.-5/A and K.-50/C from the Pesje mining area), which were operational between the years 2010 and 2011 were investigated. The major gas components are CO2 and methane. Temporal changes in the chemical and isotopic composition of free seam gases were observed within boreholes as a function of the advancement of the working face. The study also revealed that at a distance of around 120 m from the working face, the influence of coal exploitation by the Velenje Longwall Mining Method causes coalbed gas to migrate. At a distance of 70 m the lignite structure is crushed causing desorption of fixed CO2 from the coal. Differences in coalbed gas composition at the longwall panels which underlie the unmined area or under previously mined areas were found. A high CDMI {=[CO2/(CO2+ CH4)]100 (%)} index with values up to 95.6% was typical for areas of pre-mined excavation fields (South Preloge K.-130/A and Pesje area K.-5/A), while in excavation fields with no previous mining activity (North Preloge G2/C and Pesje area K.-50/C) up to 61.9 vol % of CH4 was detected. The concentration measurements and isotopic studies revealed endogenic CO2 (including CO2 originating from dissolution of carbonates) with δ13CCO2 values ranging from -7.0‰ to 5.5‰, microbial methane and CO2 with values ranging from -70.4 to -50‰ and from -11.0 to -7.0‰, respectively. Higher δ13CCH4 values ranging from -50 to -19.8‰ could be attributed to so-called secondary processes influencing the δ13CCH4 value, such as migration due to lignite excavation (escape of isotopically lighter methane). In excavation fields (G2/C and K.-50/C) with no-premining activity higher δ13CCH4 values could also be explained by migration of methane from deeper strata. The δ13CCH4 value also depended on the depth of the excavation field; at shallower levels of the excavation field (K.-5/A) a lower δ13CCH4 value was traced indicating microbial gas, while at deeper levels higher δ13CCH4 values were found.
    International Journal of Coal Geology 09/2014; 131. DOI:10.1016/j.coal.2014.05.007 · 3.38 Impact Factor
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