Experimental study of dehydration performance of re-crosslinkable preformed particle gel during extruding through an open fracture

Re-crosslinkable preformed particle gel (RPPG) has been considered to be one of the most promising gels for dealing with fracture and void space conduit (VSC) conformance problems. However, the dehydration of RPPG during its propagation in the fracture-type features and its effect on gel properties remains unclear. This paper investigates the dehydration behavior during RPPG propagating in an open fracture using matrix-free fracture model. Then the results were verified using real fractured sandstone core model. Moreover, the gel properties after extruding a fracture were studied in detail including gel dehydration and gel strength. Results reveal that the RPPG properties changed significantly with increasing propagation distance, which correlated with the gel injection rate. At high gel injection rates, the dehydration and gel strength ($G^{\prime }$) decrease with increasing propagation distance.

In contrast, the opposite result was found at low injection rates. Based on the study of the different gel injection rates, it is found that dehydration time is another key factor affecting dehydration behavior. Results also indicate that the fracture width affects gel dehydration at different locations. Dehydration was more pronounced at narrow fractures but only in the inlet section, while in the outlet section, RPPG contains more water than the initial condition. This study has profound implications for field applications. It provides new insights into the transport of RPPG in fractures and helps field engineers to optimize the gel injection operations.