Conformation and plugging properties of crosslinked polymer microspheres for profile control

•There is certain matching relation between the size of microsphere and reservoir pore.•Microspheres can be bridged in the pore-throat to play a role of plugging.•Microspheres will be deformed under the pressure and enter deep into the reservoir.•Microspheres with a smaller deformation preferably migrates in capillaries.

Shape, size, and deformation of cross-linked polymer microspheres were investigated using scanning electron microscopy (SEM), microscopy and laser diffracting measurements experiments. Capillary flow experiment, micro-visual model, nuclear-pore film filtration experiment and sand-packed model were utilized to explore the plugging mechanism of microspheres in porous media. The results demonstrated that the microspheres typically had a spherical original shape with a size ranging from a few microns to tens of microns. When the microspheres were dispersed in water, they became larger due to swelling, at a range of 10–100 μm. The microspheres can plug porous medium and there is certain matching relation between the size of microspheres and the size of reservoir pore, and they can be adsorbed, accumulated and bridged in the pore-throat to play a role of plugging. Microspheres are soft, flexible, deformable microgel particles and they will be deformed under the pressure, entering deep into the reservoir when sufficient pressure is supplied, with the ultimate purpose of the deep profile control. Moreover, the microsphere can deform to entry the small capillaries and the microsphere with a smaller deformation preferably migrates in capillaries under a certain displacement pressure.

Graphical abstractPlugging mechanism of microspheres to nuclepore membrane with different size.Figure optionsDownload full-size imageDownload as PowerPoint slide