Migration characteristics and deep profile control mechanism of polymer microspheres in porous media

Abstract

The performance and migration characteristics of polymer microspheres in porous media and the mechanism of deep profile control for oil displacement were studied by theoretical analysis, instrument detection, and physical simulation to further improve oil recovery. Polymer microspheres were expansive in water and nonexpansive in oil. The polymer microspheres with short expansion times possessed excellent mechanical shear resistance. According to the matching factor (Ra), resistance factor, and residual resistance factor, the migration of polymer microspheres in porous media was divided into four periods: transportation (Ra > 2.41), bridging plugging (1 < Ra < 2.41), elastic plugging (Ra < 1), and fatigue (microsphere breakage). The resistance factor and residual resistance factor of the polymer microspheres during the bridging and elastic plugging periods were larger than those during other periods. The deep oil displacement profile can be controlled by adjusting the occurrence positions (distance from the injection end) of these two periods. Increasing the injection rate during the transportation and bridging plugging periods and decreasing the injection rate during the elastic plugging period made elastic plugging occur farther from the injection end while maintaining the resistance factor and residual resistance factor at high levels. Aimed at the remaining oil accumulation area, the optimal profile control depth of oil displacement (distance from the injection end) of polymer microspheres in porous media can be regulated by changing the injection rate to enhance oil recovery. The simultaneous migration and expansion of polymer microspheres is the main mechanism of microsphere fluid diversion in porous media.

Intelligent sustained‐release microgel for reduced permeability of fluid channels: Synthesis and properties

“…3,4 Profile control agents have been applied in oilfields, including in-situ polymer gels, [5][6][7] particle gels 8,9 and polymer microspheres. 10,11 Microspheres have been successfully used as a deep fluid flow agent with excellent performances, 12 due to their nanometer sizes, good injection properties, and deep migration capabilities. 13,14 Moreover, microspheres have excellent dimensional and thermal stability when used as a pre-crosslinking system.…”

Profile control performance and field application of preformed particle gel in low-permeability fractured reservoir

“…For low-permeability fractured reservoirs, a good profile control agent should have the following characteristics: injectable, good plugging performance, movable and pollution-free (Zhou et al 2017). At present, the common profile control agents for fractured reservoirs include polymer gel (He et al 2009;Lu et al 2010), preformed particle gel (PPGs) (Imqam et al 2017;Sun et al 2019), polymer microspheres (Hua et al 2014;Li et al 2019), etc. As to particles like PPGs or microspheres, it is required that the initial size of the profile control agent must be smaller than the pore throat diameter of the formation; the profile control agent must expand and have certain elasticity, and can produce deformation and breakthrough under certain pressure, so as to have the advantages of good plugging performance to achieve deep profile control.…”

Numerical simulation of particulate suspension transport and permeability impairment in an actual rough fracture under normal stresses

“…With the adoption of new technologies, the visualization experiments, computed tomography (CT), nuclear magnetic resonance (NMR), and fluorescence tracking have been introduced in the core flooding experiments. [7][8][9][10][11] Although coarse images can be obtained using these improved experiments, it is still difficult to obtain the quantized relationship between the particles and porous medium.…”

“…However, it remains challenging to understand the particle distribution in porous media by using the core flooding experiments, as these experiments are still concerned with permeability loss. With the adoption of new technologies, the visualization experiments, computed tomography (CT), nuclear magnetic resonance (NMR), and fluorescence tracking have been introduced in the core flooding experiments . Although coarse images can be obtained using these improved experiments, it is still difficult to obtain the quantized relationship between the particles and porous medium.…”