Migration-plugging properties and plugging mechanism of microfoam

ABSTRACT

To gain a better understanding of the migration-plugging properties and plugging mechanism of microfoam, micromodel tests were conducted to investigate the factors controlling the bubble size and plugging mechanism of microfoam. The resistance factor, plugging ratio, and matching factor between average bubble diameter of microfoam and pore-throat diameter of core were introduced to characterize the migration-plugging properties of microfoam by core displacement experiments. The results showed that the average bubble diameter of microfoam could be tuned from 8.6 to 57.9 µm by changing the gas liquid ratio and the sandpack foam generator permeability. Microfoam showed both better injectivity and deep plugging capacity when the matching factor was 1.35–1.87 and the gas liquid ratio was 1:2–1:1. Microfoam would create a temporary blocking zone in the high permeable region through bubble accumulation, and the subsequent microfoam would flow through the low permeable region directly or by means of elastic deformation. With the increase of the gas liquid ratio, the flow pattern of the microfoam was changed from dispersed and isolated bubbles to dense and surface contact bubbles. The blocking mode of microfoam at the pore-throat was shown to shift from intermittent plugging to continuous plugging, leading to the enhancement of plugging capacity and deformability of microfoam.

GRAPHICAL ABSTRACT

KEYWORDS:

• Matching factor
• Microfoam
• migration
• plugging
• plugging mechanism