Volume 18: Sustainable Energy Solutions for a Post-COVID Recovery towards a Better Future: Part I

Visual investigation on oil recovery enhancement via polymer flooding in heterogeneous reservoir Yu Li, Huiqing Liu, Hongquan Zhang, Qing Wang, Ke Sun,Tiantian Wang,Wuchao Wang, Chuan Liu

Abstract

As an alternative, polymer flooding has been widely promoted and tested in the heterogeneous reservoir. In our earlier studies, we have recognized that oil recovery increases with the viscosity of the polymer as the displaced phase by observing the Hele-Shaw model.
Using visualization techniques, we explore the effects of water flooding and polymer flooding on fluid flow in a vertical heterogeneous reservoir filled with porous media. Based on macro-micro experimental image recognition, this study obtains the characteristics of the saturation distribution and production performance on water flooding and polymer flooding. The performance evaluation of planar sweep efficiency and vertical flow profile adjustment of polymer flooding has been systematically investigated to clarify the mechanism of enhanced oil recovery by polymer flooding. Compared with primary water flooding, the oil recovery of subsequent water flooding increases demonstrates that polymer flooding achieved better planar sweep performance based on macroscopic images. The work also qualitatively analyzed the changes of various types of residual oil during polymer flooding based on microscopic images.
Through literature and experimental research, we realized that a plethora of factors in polymer flooding may affect the development of drainage zones in heterogeneous reservoirs, including but not limited to polymer-oil mobility ratio, the timing of injection, velocity of injection, and polymer-rock surface adsorption. After optimizing the injected polymer parameters in this study, we tested the percolation condition of polymer in reservoirs with different permeability. The results displayed that the polymer easily entered the high-permeability layer and weakened its fingering phenomenon of preferential flooding channel. By the method of controlling the amount of polymer solution and observed preferential flooding channels interactions to the type of residual oil, we were able to design more comprehensive and appropriate evaluation methods for improving the performance of vertical heterogeneous reservoirs.

Keywords Visual investigation, Polymer flooding, EOR, Residual oil, Heterogeneous reservoir