Micro and macro analysis of carbonated water injection (CWI) in homogeneous and heterogeneous porous media

摘要

CO2-based EOR processes have been thoroughly investigated in the laboratory and field scales. However, many CO2 floods suffer from gas fingering and lack of sweep efficiency. Carbonated water injection (CWI) is regaining attention as it does not lack from the same issues. In CWI, dissolved CO2 is transferred from the water to the oil phase resulting in oil swelling and reconnecting of immobile oil. CWI requires less CO2, which is an advantage for offshore applications where facilities are space constrained and long transport distances of CO2 for EOR is costly. Thus, CWI has an excellent potential as an offshore EOR technique where CO2 separation facilities may already exist on the platform. The novelty of this research was to investigate the performance of water flooding and CWI in the presence of gravity using homogeneous and fractured porous media. This work is a part of a comprehensive study of the effect of geometry of porous media on the performance of CWI. In this study, the effect of CWI on vertical displacement was investigated using pressurized glass micromodels at 2.1 MPa and 21 degrees C. Secondary CWI resulted in an additional oil recovery of 16.8%, 6%, and 10.1% at 7 PV compared to water flooding in the homogeneous, horizontal fracture, and vertical fracture micromodels in the presence of gravity, respectively. The vertical oil displacement by CWI is a valuable achievement that was verified by this research.