The Japanese Ministry of Economy, Trade and Industry began, in 2002, a five-year project on CO_2 sequestration in coal seams. This project involves fundamental research into CH_4-CO_2-coal interaction, CO_2 monitoring technologies, cost reduction of CO_2 capture from flue gases, and the economics of sequestration. Another component of the project is a micro pilot test. After preliminary screening of potential sites, the Ishikari Coal Field in Hokkaido, Japan, was selected as the micro pilot test site. In 2003, a well (Shuparo IW-1) was drilled in the South Oh-Yubari district within the Ishikari Coal Field. It was the first well drilled in Japan from the surface to a coal seam for CO_2 sequestration. During drilling, coal cores were collected and sent to laboratories for analysis to determine several parameters such as the initial adsorbed volume of gas and the Langmuir constants. After the well was drilled, down-hole investigations that included well-logging, a water-injection falloff test, and a mini-frac test were also carried out. Based on the results, the coal-seam temperature, cleat porosity, absolute permeability, thickness, initial pressure, initial water saturation, fracturing pressure and fracture-closing pressure have all been estimated. In 2004, a second well (Shuparo PW-1) will be drilled. The two wells are together intended to constitute a multi-well micro pilot test site. A CO_2 huff-and-puff test will be carried out at IW-1, and a multi-well CO_2-injection/CH_4-production test conducted using both IW-1 and PW-1. This paper introduces the overall coal-seam CO_2-sequestration project and presents the results of the laboratory analyses, well-logging and water-injection falloff tests conducted to date. The data are used to predict the likely results of the future CO_2 huff-and-puff and multi-well tests. The final section of this paper presents an estimate of the likely volume of CO_2 that can be sequestered in the Ishikari Coal Field.
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