Visualized Study on a New Preformed Particle Gels (PPG) plus Polymer System to Enhance Oil Recovery by Oil Saturation Monitoring Online Flooding Experiment

After tertiary recovery from the oilfields, improving the production of the remaining hydrocarbon is always challenging. To significantly improve oil recovery, a heterogeneous composite flooding system has been developed with preformed particle gels (PPG) and polymers according to the technical approach of plugging and flooding combination. In addition, an oil saturation monitoring device and a large-scale 3D physical model were designed to better evaluate the performance of the technique. The evaluation results show that the viscosity, stability, and elasticity of the heterogeneous composite flooding system are better than the single polymer system. In addition, both systems exhibit pseudoplastic fluid characteristics and follow the principle of shear thinning. The results of seepage experiments showed that PPG migrates alternately in porous media in the manner of piling plugging-pressure increasing-deformation migration. The heterogeneous composite system can migrate to the depths of the oil layer, which improves the injection profile. In the visualization experiment, the heterogeneous composite system preferentially flowed into the high-permeability layer, which increased the seepage resistance and forced the subsequent fluid to flow into the medium and low permeability layers. The average saturation of the high, medium, and low permeability layers decreased by 4.74%, 9.51%, and 17.12%, respectively, and the recovery factor was further improved by 13.56% after the polymer flooding.

Automated summary

A heterogeneous composite flooding system, which combines preformed particle gels (PPG) and polymers, has been developed to improve the production of remaining hydrocarbon after tertiary recovery. The performance of this system was evaluated using an oil saturation monitoring device and a large-scale 3D physical model. The evaluation results indicate that the heterogeneous composite flooding system has better viscosity, stability, and elasticity compared to a single polymer system. Furthermore, both systems exhibit pseudoplastic fluid characteristics and follow the principle of shear thinning. Seepage experiments showed that PPG migrates alternately in porous media, resulting in piling plugging-pressure increasing-deformation migration. The heterogeneous composite system can migrate to the depths of the oil layer, improving the injection profile. In visualization experiments, the system preferentially flowed into the high-permeability layer, increasing seepage resistance and forcing subsequent fluid to flow into the medium and low permeability layers. The average saturation of the high, medium, and low permeability layers decreased by 4.74%, 9.51%, and 17.12%, respectively, and the recovery factor was further improved by 13.56% after polymer flooding.