Estimation method and implications of “secondary-tertiary integrated” EOR
Jialiang Zhang, Pingqi Zhao, Mingjun Cai, Ming Zhao, Ying Xiong, Xi Wu, Yang Zhang, Bo Luo
Abstract
The theory of “secondary-tertiary integrated” enhanced oil recovery (EOR) was investigated. Models and methods for estimating the secondary water-flooding recovery, tertiary chemical-flooding recovery and “secondary-tertiary integrated” EOR were established, respectively. The results indicate that the ultimate recovery factor of “secondary-tertiary integrated” EOR is greater than the aggregation of the secondary recovery factor and the tertiary recovery factor when the secondary recovery and the tertiary recovery are implemented alone. The excess recovery is attributed to the product of the increased volumetric water-flooding sweep efficiency and the difference between the oil displacement efficiencies before and after the displacing medium is changed.