A Field Study on Simulation of CO2Injection and ECBM Production and Prediction of CO2Storage Capacity in Unmineable Coal Seam

摘要

CO2sequestration into a coal seam project was studied and a numerical model was developed in this paper to simulate the primary and secondary coal bed methane production (CBM/ECBM) and carbon dioxide (CO2) injection. The key geological and reservoir parameters, which are germane to driving enhanced coal bed methane (ECBM) and CO2sequestration processes, including cleat permeability, cleat porosity, CH4adsorption time, CO2adsorption time, CH4Langmuir isotherm, CO2Langmuir isotherm, and Palmer and Mansoori parameters, have been analyzed within a reasonable range. The model simulation results showed good matches for both CBM/ECBM production and CO2injection compared with the field data. The history-matched model was used to estimate the total CO2sequestration capacity in the field. The model forecast showed that the total CO2injection capacity in the coal seam could be 22,817 tons, which is in agreement with the initial estimations based on the Langmuir isotherm experiment. Total CO2injected in the first three years was 2,600 tons, which according to the model has increased methane recovery (due to ECBM) by 6,700 scf/d.