Biomimetic functional hydrogel particles with enhanced adhesion characteristics for applications in fracture conformance control

Abstract

Fracture conformance control in reservoir can effectively improve water channel to increase crude oil displacement efficiency of subsequent waterflooding. Inspired by the remarkable underwater wet adhesion of mussel byssus, hydrogel particles which can adhere stably on the fracture rock surface in reservoir conditions could achieve long-lasting reservoir control effect. In this work, the size-controllable biomimetic functional hydrogel particles were prepared by mechanical shearing after bulk hydrogel was constructed by catechol-functionalized polyacrylamide and phenolic resin crosslinking agent. The influence of solution salinity on the aggregation and adhesion of hydrogel particles was investigated via scanning electron microscope (SEM), colloidal probe atomic force microscope (AFM) and quartz crystal microbalance with dissipation (QCM-D). The results showed that hydrogel particles maintained well-dispersed state in low-salinity water, while exhibited significant adhesion and adsorption capacity to the silica surface in simulated reservoir salinity water. This is of great importance to the practical applications that the hydrogel particles would not show enhanced adhesion to rock surfaces until the reservoir salinity water was met, which was beneficial to the in-depth migration of hydrogel particles to achieve effective deep reservoir profile control. Furthermore, the visible micro-model was designed and applied to evaluate profile control effect of hydrogel particles, and the results showed that hydrogel particles could withstand water flushing and adhere stably to the fracture surface. The waterflooding sweep efficiency was increased remarkably from 20.3% ± 2.0% to 38.8% ± 2.0%. This work would help better understand the function mechanism of hydrogel particles in reservoir control and provide novel and efficient method for the practical application in enhanced oil recovery.