Modeling preformed particle gel surfactant combined flooding for enhanced oil recovery after polymer flooding

- A mechanistic model for PPG/surfactant/polymer combined flooding was proposed.
- The interaction between PPG and surfactant was mathematically described.
- The newly presented model was validated with core flooding cases.
- Two pilots from China fields were used to verify the coupled model.
- The sensitivity of different parameters to the recovery factor was discussed.

Preformed Particle Gel (PPG) surfactant combined flooding, designed to simultaneously improve the sweep efficiency and displacement efficiency, has emerged as a promising Enhanced Oil Recovery (EOR) method after polymer flooding. The fundamental mechanisms have been investigated by many lab experiments and the feasibility has been evaluated by some field applications. However, there is no model that can handle this combined EOR process. In this paper, a mechanistic model is proposed to predict the EOR performance after polymer flooding. This new coupled model incorporates the surfactant transport module into the model of PPG treatment after polymer flooding. Especially, the interaction mechanisms between PPG and surfactant are mathematically described according to the lab experiments. An implicit pressure explicit composition method is adopted to numerically solve the coupled model. The newly presented model is firstly validated with a commercial simulator and some core flooding experiments. Then, the verified model is employed to predict the performance for actual field pilot cases. Parameters analysis is conducted on a conceptual model for PPG conformance control after polymer flooding. The results show that the coupled model provides an efficient and accurate method for predicting PPG-surfactant flooding performance after polymer flooding, which aids to determine the technical feasibility of the field project.