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PERSPECTIVES OF METHANE RECOVERY FROM COAL BEDS IN POLAND J. Siemek, S. Rychlicki and C. Rybicki, University of Mining and Metallurgy, Department of Petroleum Engineering, Cracow, Poland. Abstract. Coal beds and methane-both free and adsorbed in coal, appear in the south of Poland in the Upper Carboniferous in two basins: Upper Silesian Coal Basin (USCB) and Lower Silesian Coal Basin (LSCB). At the depth of 3o(r1600 m the methane reserves are estimated at 350 to 1300 rnld m3 for USCB and ca. 20 mld m3 for LSCB. Methane content in coal varies between O and 22 m3/tpc, to significantly increase from the depth of 600 m, reaching average values of 4.7-7.0 m3/tpc. Discrepancies in estimation are due to different calculation methods; the full geostatistical analysis method- structural analysis-was not applied, however. Prognoses, apparently optimistic, determine the final recovery of methane from coal beds for ca. 5 mld m3/year for USCB, and ca. 300 min m3 for LSCB, which together with the production from the Polish gas reservoirs would give ca. 12 mld m3/year in the year 2010. For the comparison's sake, the Polish consumption of gas is now ca. 11.8 rnld m3, being about 9% of total primary fuel consumption in Poland. Methane from coal beds was recovered earlier but used in less quantities (ca. 190 mln m3/year). It came from 18 USCB mines. Utilization of methane from coal basins aims at the reorientation of the Polish energy industry to the increased use of hydrocarbon fuels. Besides, the use of methane, especially in the Upper Silesia region, will significantly improve the ecological situation, limiting the emissions of SO,, CO,, NO, and dusts. The priorities of methane utilization are as follow: delivery to local receivers, for households, near big agglomerations Katowice, Opole, Bielsko; heating, housing estates, country, balance top needs ; for local industrial works, metallurgical, ceramic, chemical plants, glass works; electric gener- ation. Now a few foreign companies are interested in methane exploitation in Poland, e.g. McCormick Energy Inc., USA, Amoco, Conoco, Electrogaz Ventures (Poland-USA), Metanel (Poland). There has been an auction of the licence for methane exploitation. The fact that methane appears in coal beds has been known since the beginning of the mining industry. The gas was generally treated as a consider- able hindrance in the exploitation of coal as a fuel. It has created a great hazard'for the miners in the form of explosions and outbursts of rock and coal. For more than ten years the matter of methane enclosed in coal, treated as a fuel, has raised interest in many countries, e.g. U.S.A., Australia, China. Research has been carried out on the content in coal, ways of deposition as well as methods of exploitation and leakproof transport to the surface. Poland has also taken an interest in methane, coming from coal, as a fossil fuel. There are three coal basins in Poland (Fig. 1): - Upper Silesian Coa
Abstract This paper presents the results of a preliminary investigation of the coalbed methane potential of the Zonguldak Basin in Turkey. A stochastic approach is used in the investigation primarily because of the lack of sufficient data. The results clearly indicate the adequacy and the advantage of the stochastic approach over the deterministic procedures. The Monte Carlo simulation is used to obtain the probability distribution of in-situ and recoverable coalbed methane reserves in the Zonguldak Basin. An economic evaluation of a potential development project is also presented. It is shown that despite the conservative estimates of the reserves, coal bed methane production from the Zonguldak Basin is a feasible project. P. 227
This new technology uses a downhole chemical-sensing The two most significant reservoir parameters for evaluating tool developed specifically for the CBM industry. The key (amount of gas stored in coal divided by the maximum instrument in this tool is a Raman spectrometer that has amount of gas that the coal can hold, in %). Historically, these been downsized and ruggedized so that it can be lowered by parameters could be obtained only by cutting a core of the wireline into a 5-in.-diameter The Raman effect was coal, placing the core sample in a desorption canister, and discovered in 1928 and has been used in many industries for waiting a few months for the gas to desorb from the coal. The Raman effect occurs when light Once desorption was complete, a representative sample of scatters from a molecule with a slightly changed energy, or the coal was sent to a laboratory for determination of the color, caused by excitation of the molecule's chemical bonds.
Of a relatively marginal significance for the conventional oil & natural gas industry, coal bed methane (CMB)has been particularly promoted in some specific coal oriented-countries (USA, China, UK), despite constraints linked to environmental concerns. Papers will concentrate on the technical challenges of projects in countries such as USA, Poland, China and the UK and other former coal production countries utilising CO2 sequestration to promote gas production whilst gaining credit for carbon storage.
Canada has over 700 Tcf of CBM resource in place, with over half of this resource in Alberta and the Western Canadian Sedimentary Basin (WCSB).1-4 Starting in late 2001, commercial production of CBM in Canada began with the “dry” Horseshoe Canyon CBM play in Alberta.5 Today, there are over 4,000 CBM wells in Canada, with over 2,000 tied in and producing over 200 MMcf/D. With over 3,000 wells planned for 2005, year-end rates are expected to reach up to 500 MMcf/D by year-end 2005 and several thousand future wells are estimated to produce over 2 Bcf/D by 2015 and over 3 Bcf/D by 2025.6-7 With current Canadian natural gas production at ~17 Bcf/D, this represents up to 20% of Canada's future gas deliverability, assuming negligible growth in total production. In addition to adding to Canada's gas production, Canadian CBM reservoirs may also prove to be an effective “sink” for disposing of excess CO2 production. The Alberta Research Council (ARC) has been conducting basic and applied research in this area since 1996 and currently has three projects ongoing, including two in the field. In addition to storing excess CO2, these processes have the potential of enhancing CBM production by up to 40% in low permeability reservoirs. With CBM production well established in North America, there is potential to enhance CBM production and dispose of CO2 simultaneously in the future, a true “win-win” association. With significant CBM resources being evaluated around the world, including China, India, Australia, eastern Europe, and elsewhere, there is potential for technology transfer to not only produce significant CBM, but to develop sinks for excess CO2 production as well.
CBM RESOURCE IN CANADA
Figure 1 shows the major coal basins in Canada. The Geologic Survey of Canada (GSC), the Alberta Geologic Survey (AGS),and the British Columbia Ministry of Energy and Mines (BC MEM)estimate there is over 700 Tcf of CBM resource in Canada, with over 500 Tcf in Alberta (AB) and 90 Tcf in British Columbia (BC) alone.1-4 Figure 2 shows the major CBM target formations in Alberta, including the Mannville coals (267 Tcf resource),Horseshoe Canyon and Belly River coals (66 Tcf resource),the Ardley coals (53 Tcf resource)and others. Figure 3 shows the major CBM basins in BC, with about 90 Tcf distributed in the NE BC portion of the WCSB, SE BC, inter-mountain basins, and Vancouver Island. The remaining coals with CBM potential are in Saskatchewan, the Yukon and Northwest Territories, and Nova Scotia. Despite the presence of this large resource, until late 2001, there was no significant CBM production in Canada.
An experimental procedure for determining the effectiveness of CO2 injection into methane-containing coal samples for the purpose of enhancing methane production is described. Experimental results on production is described. Experimental results on both dry and water saturated samples reveal that CO2 injection greatly enhances both production rate and recover efficiency. Most effective is a cyclic CO2 injection-gas production technique which recovered essentially all of the adsorbed methane in the 3 1/2" core samples used in the experiments.
The coal which lies buried beneath the United States at depths of less than 3000 feet is thought to contain nearly 300 trillion standard cubic feet of pipeline quality gas. This exceeds the current pipeline quality gas. This exceeds the current proved gas reserves in the U.S. and represents a proved gas reserves in the U.S. and represents a significant possible supplement to dwindling supplies. The natural gas found in virgin coal beds is predominantly methane, usually exceeding 80%. Very predominantly methane, usually exceeding 80%. Very small percentages of ethane, propane, butane and pentane have been detected. Carbon dioxide and pentane have been detected. Carbon dioxide and nitrogen may be as high as 15% in gas from virgin coal. Most of the gas present in coal beds is adsorbed on the coal surfaces and desorption is normally a very slow process.
In addition to the desirability of producing this gas as an energy source there is the added important advantage from a safety standpoint of demethanating a coal bed prior to mining. Attempts to produce the gas in coal through vertical well bores by pressure drawdown have generally not been commercially successful because of low production rates. Differing theories on the transport of gases through coal have been proposed by Cervik, Kissell, Skidmore and Chase and Kuuskraa, et. al to explain these low production rates. None of these has concluded that desorption rate is the mechanism which controls production rates from wells drilled into coal beds. production rates from wells drilled into coal beds. A key publication by Every and Delosso in 1972 showed that carbon dioxide proved to be very effective in displacing methane from crushed coal under laboratory imposed flow conditions at ambient temperature. This led to the proposal that competitive adsorption-desorption of methane by carbon dioxide might provide an efficient means for rapid degassification of coal y beds and thereby increased recovery rates of methane from vertical well bores. This paper describes a laboratory procedure for measuring the effectiveness of carbon dioxide in replacing methane from 3 1/2" diameter samples of Pittsburgh coal and also presents the experimental results.
The coal from the Pricetown mine in West Virginia was delivered in large lumps which were then stored under water until cored for use in the experiments.
The experimental apparatus is represented schematically in Figure 1 and pictorially in Figure 2. The pressure vessels used were 4 inch (10.16 cm) I.D. ant pressure vessels used were 4 inch (10.16 cm) I.D. ant 12 inches (30.48 cm) long. The vessels were designed for operating pressures of 100 psi (4.78 Pa) and 200 psi (9.56 Pa). The coal samples were cut to diameters of 3 1/2 or 3 3/4 inches (8.89 or 9.555 cm) and varying lengths between 2 to 4 inches (5.08 to 10.16 cm) and stacked in the vessels to a total height of approximately 11 1/2 inches (29.21 cm). The system was evacuated for several hours. Methane was expanded from a constant volume pressure cylinder into the vessel containing the coal resulting in methane adsorption on the coal surfaces. As methane was being adsorbed, the pressure in the system declined and the amount of pressure in the system declined and the amount of methane adsorbed was determined by material balance. At some arbitrarily selected time, usually six to eight days, the pressure in the system was noted, and the amount of adsorbed methane calculated. In some cases, in order to get a greater quantity of methane adsorbed, the pressure was increased and the process repeated several times. When the desired amount of methane had been adsorbed the excess gas in the vessel was vented to atmospheric pressure. At this point the natural desorption production cycle was begun and continued until no more gas was being produced, or was stopped after some arbitrarily chosen time interval.