Effect of Viscosity Action and Capillarity on Pore-Scale Oil–Water Flowing Behaviors in a Low-Permeability Sandstone Waterflood

Tao Ning, Meng Xi, Bingtao Hu, Le Wang, Chuanqing Huang and Junwei Su
Additional contact information
Tao Ning: The Management Headquarters of Water Injection Project, Yanchang Oil Field Co. Ltd., Yan’an 716000, China
Meng Xi: The Management Headquarters of Water Injection Project, Yanchang Oil Field Co. Ltd., Yan’an 716000, China
Bingtao Hu: School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Le Wang: Mechanical Engineering College, Xi’an Shiyou University, Xi’an 710065, China
Chuanqing Huang: School of Chemistry and Chemical Engineering, Shaanxi University of Science and Technology, Xi’an 710021, China
Junwei Su: School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, China

Energies, 2021, vol. 14, issue 24, 1-30

Abstract: Water flooding technology is an important measure to enhance oil recovery in oilfields. Understanding the pore-scale flow mechanism in the water flooding process is of great significance for the optimization of water flooding development schemes. Viscous action and capillarity are crucial factors in the determination of the oil recovery rate of water flooding. In this paper, a direct numerical simulation (DNS) method based on a Navier–Stokes equation and a volume of fluid (VOF) method is employed to investigate the dynamic behavior of the oil–water flow in the pore structure of a low-permeability sandstone reservoir in depth, and the influencing mechanism of viscous action and capillarity on the oil–water flow is explored. The results show that the inhomogeneity variation of viscous action resulted from the viscosity difference of oil and water, and the complex pore-scale oil–water two-phase flow dynamic behaviors exhibited by capillarity play a decisive role in determining the spatial sweep region and the final oil recovery rate. The larger the viscosity ratio is, the stronger the dynamic inhomogeneity will be as the displacement process proceeds, and the greater the difference in distribution of the volumetric flow rate in different channels, which will lead to the formation of a growing viscous fingering phenomenon, thus lowering the oil recovery rate. Under the same viscosity ratio, the absolute viscosity of the oil and water will also have an essential impact on the oil recovery rate by adjusting the relative importance between viscous action and capillarity. Capillarity is the direct cause of the rapid change of the flow velocity, the flow path diversion, and the formation of residual oil in the pore space. Furthermore, influenced by the wettability of the channel and the pore structure’s characteristics, the pore-scale behaviors of capillary force—including the capillary barrier induced by the abrupt change of pore channel positions, the inhibiting effect of capillary imbibition on the flow of parallel channels, and the blockage effect induced by the newly formed oil–water interface—play a vital role in determining the pore-scale oil–water flow dynamics, and influence the final oil recovery rate of the water flooding.

Keywords: water flooding; pore scale; enhanced oil recovery; viscosity; capillarity (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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