Publication Date:
2020-06-27
Description:
The aim of this study was to determine the coal characteristics in the Chico-Lomã coalfield, Brazil and to evaluate the potential of natural gas associated with the coal seams (CBM), by carrying out a test well (CBM001-CL-RS) for collecting coal samples, followed by gas desorption measurements, and petrographical and chemical analyses of the coals and their methane adsorption capacities. The gas collected was analyzed for gas composition, stable carbon and hydrogen isotopes. The results indicate a cumulative coal thickness of 11.46 m in well CBM001-CL-RS, associated with an igneous intrusion of 10 m thickness. In the contact zone with the intrusion, the organic matter is severely altered with partial transformation of the coal to natural coke at distances less than 2 m from the intrusion. The ash content, based on proximate analysis, shows a variation from 29.1 to 82.8 wt.%. The sulphur content ranges from 0.43 to 3.89 wt.% and shows higher values in samples from the top of the Rio Bonito Formation. The gas desorption measurements range from 0.05 to 0.74 cm3/g, with methane being the predominant gas (〉90%). A thermal origin of the gas is suggested by C and H isotopes and the C1 (methane) to C3 (propane) hydrocarbon distribution. The methane adsorption capacity of the samples varies from 2.50 to 6.50 cm3/g. Changes in microporosity related to thermal alteration may have a significant impact on the gas-holding capacity of samples located near the contact to the intrusion. For the study area, a 3D geological model was generated to estimate the volume of coal in the coalfield, followed by assessment of the gas volume associated with the coal. Based on the 3D model, a preliminary appraisal indicates resources of 7.2 billion tons of coal for the Chico-Lomã coalfield, associated with 2.7 billion m3 of gas.
Print ISSN:
0144-5987
Electronic ISSN:
2048-4054
Topics:
Energy, Environment Protection, Nuclear Power Engineering
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Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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