Prospect evaluation of CO2 sequestration in coal beds of Anambra Basin, Nigeria

Sequestrating carbon dioxide (CO2) for enhancing methane production from coal beds is one of the approaches being advanced to reduce the concentration of CO2 in the Earth's atmosphere. Some aspects of CO2 sequestration and coalbed methane (CBM) exploration within three coal seams (seam I-III) in the Anambra Basin, Nigeria was investigated in this study. The rank, grade and type of coals were determined using proximate/ultimate and petrographic analyses, fourier transform infrared reflectance (FT-IR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results from these analyses were used to determine the suitability of the coal for CO2 storage and CBM/CO2-ECBM production. Physicochemical properties including volatile matter (27.03, 72.74 and 15.14%), fixed carbon (48.60, 30.10 and 54.30%), and the calorific values (13,103, 11,517 and 14,263 Btu/lb), were used to determine the coal rank based on the ASTM standard for coal ranking. This revealed that all the coal samples fell within the subbituminous low-rank coals to high volatile C bituminous coals. Petrographic analysis revealed that the main lithotypes in the coal seams are fusain, durain with few vitrains. The effective storage capacity estimated using the Carbon Sequestration Leadership Forum (CSLF) methodology, indicated that Seam III is the most promising coal seam with the largest CO2 storage capacity of 5.77 × 109 tons around the Enugu area. Finally, this study has provided insights into the coal beds in the Anambra Basin for the implementation of CBM, CO2-ECBM production, and the potential for CO2 storage projects