Abstract
The particles, water and oil three-phase flow behaviors at the pore scale is significant to clarify the dynamic mechanism in the particle flooding process. In this work, a newly developed direct numerical simulation techniques, i.e., VOF-FDM-DEM method is employed to perform the simulation of several different particle flooding processes after water flooding, which are carried out with a porous structure obtained by CT scanning of a real rock. The study on the distribution of remaining oil and the displacement process of viscoelastic particles shows that the capillary barrier near the location with the abrupt change of pore radius is the main reason for the formation of remaining oil. There is a dynamic threshold in the process of producing remaining oil. Only when the displacement force exceeds this threshold, the remaining oil can be produced. The flow behavior of particle–oil–water under three different flooding modes, i.e., continuous injection, alternate injection and slug injection, is studied. It is found that the particle size and the injection mode have an important influence on the fluid flow. On this basis, the flow behavior, pressure characteristics and recovery efficiency of the three injection modes are compared. It is found that by injecting two kinds of fluids with different resistance increasing ability into the pores, they can enter into different pore channels, resulting in the imbalance of the force on the remaining oil interface and formation of different resistance between the channels, which can realize the rapid recovery of the remaining oil.
Highlights
Water flooding is a primary measure for enhancing oil recovery in the oil development.in the water flooding process, water flows along the pore channels with smaller resistance
In the water flooding process, water flows along the pore channels with smaller resistance
Water flows in from the left and out from the two outlets on the right. It can be seen from the figure that the water cut channel is formed along the inlet and outlet direction after water flooding, and the remaining oil is mainly concentrated on both sides of the water cut channel
Summary
Water flooding is a primary measure for enhancing oil recovery in the oil development. Due to restriction of the technology of measurement in porous media, the dynamic mechanism of oil, water and particles in rock pore channels is studied mainly by numerical simulation, especially macrosimulation. Kokubun et al [15] developed a simple model for the transport of polymer particles in an oil and water flow in a porous medium, which takes into account the clogging/unclogging of pore throats. What controls the particle–oil–water flow behaviors in particle flooding with different strategies, and how to choose the appropriate strategy for rapid and efficient oil recovery needs to be further investigated. The newly developed VOF-FDM-DEM coupled model [16] is employed to investigate the pore-scale particle–oil–water flow behaviors in the several different particle flooding processes.
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