Overview and Present Status of the CO2 Geosequestration in Coal Seams Project in Japan

Abstract

In 2002, the Japanese Ministry of Economy, Trade, and Industry began a 6-yr project on carbon dioxide (CO2) sequestration in coal seams entitled Japan CO2 Geosequestration in Coal Seams Project (JCOP), a component of the Carbon Dioxide Sequestration and Effective Use Program. The goal of JCOP is to develop a series of processes that can (1) extract the CO2 discharged from thermal power plants and other large-scale emitters, (2) fix it in a stable state within coal seams, and in the process (3) recover methane (CH4) as a clean energy source. The project involves fundamental research into CO2 adsorption on coal, CO2 monitoring methods that ensure the safety of the sequestration process, and micropilot tests. From analyses of JCOP results obtained to date, several outcomes can be highlighted. (1) A total of 461 t of CO2 was injected at an average rate of 3.0 tons/day. (2) Carbon dioxide breakthrough has not yet been observed. (3) An enhanced coalbed methane effect was observed. (4) Coal-seam permeability changed dynamically because of coal-matrix swelling or shrinkage. (5) Nitrogen (N2) injection was effective in recovering the lost injectivity associated with coal swelling. (6) A history-matched model was constructed for the micropilot tests based on coal properties determined in situ or with laboratory measurements. (7) No signs of CO2 leakage have been observed so far.