Influence of Polymer Viscoelasticity on Microscopic Remaining Oil Production

Abstract

To investigate the impact of polymer viscoelasticity on microscopic remaining oil production, this study used microscopic oil displacement visualisation technology, numerical simulations in PolyFlow software, and core seepage experiments to study the viscoelasticity of polymers and their elastic effects in porous media. We analysed the forces affecting the microscopic remaining oil in different directions, and the influence of polymer viscoelasticity on the displacement efficiency of microscopic remaining oil. The results demonstrated that the greater the viscosity of the polymer, the greater the deformation and the higher the elasticity proportion. In addition, during the creep recovery experiment at low speed, the polymer solution was mainly viscous, while at high speed it was mainly elastic. When the polymer viscosity reached 125 mPa·s, the core effective permeability reached 100 × 10−3 μm2, and the equivalent shear rate exceeded 1000 s−1, the polymer exhibited an elastic effect in the porous medium and the viscosity curve displayed an ‘upward’ phenomenon. Moreover, the difference in the normal deviatoric stress and horizontal stress acting on the microscopic remaining oil increased exponentially as the viscosity of the polymer increased. The greater the viscosity of the polymer, the greater the remaining oil deformation. During the microscopic visualisation flooding experiment, the viscosity of the polymer, the scope of the mainstream line, and the recovery factor all increased. The scope of spread in the shunt line area significantly increased, but the recovery factor was significantly lower than that in the mainstream line. The amount of remaining oil in the unaffected microscopic area also decreased.

A comprehensive review of viscoelastic polymer flooding in sandstone and carbonate rocks

“…Wang et al 108 recommended using high molecular weight polymers primarily in high-permeable rocks, while limiting polymer molecular weight in low-permeable reservoirs to minimize mechanical degradation issues. Choosing the right polymer for tight rock formations is crucial, as an unsuitable polymer can accelerate mechanical degradation, resulting in lower viscosity and viscoelasticity within the porous medium 132 . In this context, Ghosh and Mohanty 133 have explored techniques like mechanical shear degradation and aggressive microfiltration to optimize HPAM polymer properties for successful injection into low-permeability carbonate reservoirs.…”

A review of crude oil emulsification and multiphase flows in chemical flooding

“…Kowalewski et al 78 and Boassen et al 79 proposed a method combining cryo‐SEM techniques and environmental SEM techniques. SEM can be used to observe the local remaining oil distribution in a sample at a certain moment, but due to its small scale and inability to perform dynamic monitoring, its application to flowing fluids is limited 80 …”

“…SEM can be used to observe the local remaining oil distribution in a sample at a certain moment, but due to its small scale and inability to perform dynamic monitoring, its application to flowing fluids is limited. 80 According to the oil distribution type of chemical flooding, Wang 81 proposed several important flow forms: continuous, slug, oil film, oil threadlike, and emulsion flows. For continuous, slug, oil film and oil threadlike flows, oil and water relative permeability is a function of water saturation.…”

A New Method for Calculating the Relative Permeability Curve of Polymer Flooding Based on the Viscosity Variation Law of Polymer Transporting in Porous Media

“…However, none of the above studies paid enough attention to this aspect. Some literature studied the mechanism and characteristics of polymer solution [32][33][34][35][36][37][38][39], especially HAP [40][41][42][43], seeping in porous media. However, no research described the viscosity of polymer solutions in different core positions and water saturations quantitatively.…”