Overview of laboratory and modeling studies of carbon dioxide sequestration in coal beds

One of the approaches suggested for sequestering CO2 is by injecting it in coal-bed methane (CBM) reservoirs. Despite its potential importance for CO2 sequestration, to our knowledge, CO2 injection in CBM reservoirs for the purpose of sequestration has not been widely studied. Furthermore, a key element missing in most of the existing studies is the comprehensive characterization of the CBM reservoir structure. CBM reservoirs are complex porous media because in addition to their primary pore structure, generated during coal formation, they also contain a variety of fractures, which may potentially play a key role in CO2 sequestration because they generally provide high permeability flow paths for both CO2 and CH4. In this paper, we present an overview of our ongoing experimental and modeling efforts, which aim to investigate the injection, adsorption, and sequestration of CO2 in CBM reservoirs, the enhanced CH4 production that results, and the main factors that affect the overall operation. We describe the various experimental techniques that we utilize and discuss their range of application and the value of the data generated. We conclude with a brief overview of our modeling efforts aiming to close the knowledge gap and fill the need in this area.