Study on Distribution Characteristics and Displacement Mechanism of Microscopic Residual Oil in Heterogeneous Low Permeability Reservoirs

Abstract

In order to explore the development methods suitable for heterogeneous low permeability reservoirs and study the distribution characteristics of residual oil, photoetched glass and artificial core models with three permeability ratios of 1, 6, and 9 were prepared in this research. Three displacement schemes including polymeric surfactant flooding, polymeric surfactant with binary flooding, and binary flooding were designed at the same expenses to obtain the displacement mechanism of various residual oil saturations. The results show that the best displacement efficiency can be achieved by polymeric surfactant flooding, followed by polymeric surfactant with binary flooding, and binary flooding for the models with the same permeability ratio. Binary flooding mainly activates cluster and oil drop residual oils, polymeric surfactant with binary flooding mainly activates cluster, oil film, and column residual oils, whereas polymeric surfactant flooding mainly activates cluster, oil drop, and column residual oils. In addition, with the increase of the model permeability ratio, the recovery ratio of water flooding decreases, whereas the enhanced oil recovery and the variations in residual oil saturation gradually increase after carrying out different displacement measures. The viscoelastic and shearing effects of the polymeric surfactant flooding system can better displace the residual oil, assisting in the further development of heterogeneous low permeability reservoirs.

Optimized hydrophobic magnetic nanoparticles stabilized pickering emulsion for enhanced oil recovery in complex porous media of reservoir

“…The residual oil in the small pores was mainly in the cluster and column forms while the residual oil in the membrane and column forms was mainly distributed in the large pores, with a small amount of the residual oil in form of islets, as shown in Figures 7A, C. Clustered residual oil continuously distributed in the small pores was the main form of residual oil distribution after water flooding (Fang et al, 2019).…”

Experimental Investigation of the CO2 Flooding Characteristics of Tight Sandstone Reservoirs Using a High-Temperature and -Pressure Visualization Apparatus

“…On the contrary, the microscopic visualization model could intuitively characterize the microscopic seepage mechanism of oil and gas. At present, the visualization models include an etched-glass and digital model from advanced imaging devices. − Yun et al (2020) established a glass-based micromodel to represent the carbonates and revealed the surfactant-assisted oil recovery mechanism . Song et al (2020) studied the effect of different CO 2 injection rates on CO 2 saturation and mobility using a two-dimensional homogeneous model .…”