Numerical Assessment of the Migration Characteristics of CO2 Geological Sequestration in Deep Saline Aquifer

• Main Authors: Rui-tang Sung, 宋睿唐
• Other Authors: Ming-hsu Li
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/35887924227786965690

博士 === 國立中央大學 === 水文與海洋科學研究所 === 102 === Reductions of CO2 emissions to mitigate global warming are an inevitable trend in the world. Taiwan government has been aggressively promoting the studies of carbon dioxide capture and carbon dioxide geological sequestration (CGS) to investigate the feasibility of such mitigation techniques. The annual CO2 emission in Taiwan was estimated as high as 0.24 billion tons. The majority of CO2 emission sources are the thermal power plants and industrial sectors (e.g., cement mills, steel mills, petrochemical industry etc.), and each contributed about one third of annual CO2 emissions in Taiwan. Due to requirements of fossil-fuel importation and cooling water acquirements, most of thermal power plants distributed along the North and West costal lines of Taiwan. Advantages of extensive and well-developed sedimentary formations along West costal area of Taiwan provide massive volume for CGS practices. Preliminary investigations showed that the Kuanyin Plateau, Taihsi Basin, and Tainan Basin are the potential area for CGS. The Changhua Coastal Industrial Park (CCIP) potential site was located in the southern part of the Taihsi Basin and near by the Taichung Power Plant and Mailiao Power Plant. To evaluate the feasibility and risk of CGS practices in Taiwan, intensive geophysical explorations and numerical assessments are needed. In this study, we utilize the TOUGHREACT/ECO2N simulator to perform a series of numerical simulation and assessment for CGS at the CCIP Site. Objective reservoir was located from Kueichulin Formation, to upper part of Kuanyinshan Sandstone with thickness of 400 meter and beneath the low permeability caprock by the Jinshui Shale. Sloping and layered heterogeneous formations were composed of interbedding sandstone and shale that became thinner from East to West. Simulation area is 121 km2 (11 km 11 km) with single injection well in the center and injection point at -2674 meter. Injection of CO2 is assumed with a constant injection rate of 1 Mt/year for the first fifty years and total simulation period is 500 years. Characteristics of pore pressure differences, phase change of injected CO2, pore water drying-out, and subsequent halite precipitation during CO2 injection period and migration behavior of CO2 plume, pattern of cross-sectional CO2 plume, and trapping component analysis are simulated and analyzed with several simulation studies (e.g., cases of the non-refined grids and local refined grids, physical transport and reactive-transport). At 500 years, simulation results show that the effects of porosity differences are minor to the lateral migration of CO2 Plume. The simulation cases with local refined grids can improve on phase change evolution of injected CO2 and the spatial distribution pattern of CO2 plume in sloping and layered heterogeneous formations. The maximum migration distances of CO2 plume are 2700 meter and 2300 meter toward upslope direction of formation below the Taiwan Strait and toward downslope direction of onshore area, respectively.