Potential of a new water-soluble agent for enhancing heavy oil recovery: A pore-scale investigation

Abstract

The two-phase viscosity modifier (T-PVM) is a new chemical agent for enhancing sweep and displacement efficiency in heavy oil reservoirs due to multiple-effects of reducing oil viscosity by emulsifying and increasing water viscosity. In the work, the dynamic interfacial tension (IFT) between simulated oil and chemical solution, viscosity, rheological characteristics, emulsification and stability of emulsion are measured to evaluate performance difference among the agents. Then, microfluidic visualization experiments were performed for subsequent chemical flooding after initial water flooding. Based on the advanced image processing technology, morphology and migration characteristics of remaining oil were described quantitatively and the mechanism of enhanced oil recovery was explored. Results show that large amount of residual oil are remaining in the non-main streamline area and dead-end pores after water flooding, which is observed in the morphology of spot, membrane, column, cluster and network. There would be migration path separation between polymer and surfactant during surfactant-polymer (SP) combination flooding. However, T-PVM, as a single chemical agent, penetrates in remaining oil and emulsifies columnar and membrane-shaped oil, which erodes the cluster and network-shaped oil simultaneously. Compared to the traditional viscosity reducer (VR) and SP flooding, multi-effective T-PVM enhances microcosmic sweep efficiency by approximately 35.93% and 21.83%, respectively. It is thereby expected that T-PVM flooding is effective for enhancing heavy oil recovery using the chemical cold flooding.