PREDICTION OF INJECTION EFFICIENCY OF CARBON DIOXIDE IN THE JANGGI BASIN, KOREA USING INTEGRATED NUMERICAL METHODS

Using a numerical model integrated with an empirical mathematical model, the injection efficiency (i.e., injection rate and injectivity) of carbon dioxide was predicted at a pilot-scale demonstration site in the Janggi Basin, Korea. First, a simple numerical model is applied to estimate the fluid pressure and temperature at the well bottom corresponding to the carbon dioxide injection pressure and temperature at the well head. This model can predict one-dimensional distributions of the fluid pressure and temperature in the injection well based on assumptions of transitions of the hydrostatic fluid pressure and the isenthalpic fluid temperature. The fluid pressure difference between the well bottom and the reservoir rock far from the injection well, and the carbon dioxide properties such as density and dynamic viscosity at the well bottom are also estimated. Second, an empirical mathematical model is applied to estimate the carbon dioxide injectivity of a target injection system at the site. This model consists of a set of empirical mathematical equations, which are functions of the three main factors of hydrogeological properties of the reservoir rock, contact area between the injection well and the reservoir rock, and kinematic viscosity of carbon dioxide at the well bottom. The carbon dioxide injectivity corresponding to wide ranges of carbon dioxide injection pressure and temperature at the well head is estimated under given properties and specifications of the target injection system. The injection rate is also calculated as multiplying the injectivity by the fluid pressure difference. The injection efficiency in terms of the injectivity and injection rate is also summarized as a set of characteristic diagrams. These characteristic diagrams give intuitive information to determine optimal design and operation scheme of carbon dioxide injection system. Therefore, it is expected that the integrated numerical methods and their applications presented in this study can be utilized as reasonable and practical guidelines for geologic storage of carbon dioxide. This work was supported by the Korea CCS 2020 Project of the Korea Carbon Capture and Sequestration R&D Center (KCRC) funded by the National Research Foundation (NRF), Ministry of Science and ICT (MSIT), Korea.