Investigation on matching relationship between dispersed particle gel (DPG) and reservoir pore-throats for in-depth profile control

The current study aims at in-depth profile control to further improve oil recovery by studying the matching relationship between the size of dispersed particle gel (DPG) and geometry of reservoir pore-throat. The DPG products with different sizes were prepared, and their microscopic characteristics and particle size distributions were analyzed. The matching factor, which was defined as the ratio of average size of DPG particles to mean size of pore-throats, was introduced to represent the matching relationship. The injection properties and plugging capacities were systematically studied by a series of core flooding experiments to optimize the matching factor. The matching factor was optimized from 0.21 to 0.29 depending on both the injection pressure and the plugging rate. In addition, the results of multi-point pressure measurement experiment verified that the DPG particles exhibited good in-depth migration and plugging ability within the optimized matching factor values. Meanwhile, scanning electron microscope (SEM) was used to study the distribution of DPG particles in porous media. The results intuitively showed that the DPG particles can migrate to the deep of porous media and induce effective plugging to the pore-throats. Moreover, the enhanced oil recovery experiments for different matching factors were conducted, and the mechanisms for enhanced oil recovery by DPG with different matching factors were proposed. The enhanced oil recovery with an optimized matching factor was much higher than that with a smaller or larger matching factor. Owing to good in-depth migration and plugging ability of DPG particles with optimal matching factors, the subsequent injected water was diverted into low permeability zones with high oil saturation and, consequently, widely swept the remaining oil in low permeability zones. (C) 2017 Elsevier Ltd. All rights reserved.