%0 Journal Article
%T A Field Study on Simulation of CO2 Injection and ECBM Production and Prediction of CO2 Storage Capacity in Unmineable Coal Seam
%A Qin He
%A Shahab D. Mohaghegh
%A Vida Gholami
%J Journal of Petroleum Engineering
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/803706
%X CO2 sequestration 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 CO2 sequestration processes, including cleat permeability, cleat porosity, CH4 adsorption time, CO2 adsorption time, CH4 Langmuir isotherm, CO2 Langmuir 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 CO2 injection compared with the field data. The history-matched model was used to estimate the total CO2 sequestration capacity in the field. The model forecast showed that the total CO2 injection 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 CO2 injected 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. 1. Introduction Fossil fuels are currently playing a significant role in the whole world¡¯s energy supply. However, its damage to the environment, especially the CO2 emission resulting in the green house effect, has gotten more and more attention. At present, several geological CO2 sequestration technologies, such as CO2 injection into saline aquifer, CO2-EOR, CO2-ECBM, and so forth, have been studied to minimize the CO2 release into the atmosphere, and these projects have been operating all over the world [1¨C6]. Studies have shown that unmineable coal seams (seams too deep or too thin to be mined economically) are pretty attractive as one of the promising options for CO2 sequestration because of their large CO2 sequestration capacity, long time CO2 trapping, and extra enhanced coal-bed methane (ECBM) production benefits [1, 7¨C10]. Field experience with CO2 injection into coal seam is limited, although field tests are planned or are being conducted in the USA, Canada, Poland, Australia, and Japan [3]. However, unlike conventional reservoirs, gas flow in the coal seams can cause the cleat permeability and porosity variation during the injection/production process. Once gas is injected and adsorbed on the coal matrix, the matrix will swell, and correspondently decrease the cleat permeability and porosity [11, 12]. Due to its special features and the nature of gas retention in CBM reservoirs, simulating the production and injection
%U http://www.hindawi.com/journals/jpe/2013/803706/