Abstract: Preformed particle gels (PPGs) have been widely used to control water production in high-temperature and high-salinity fractured reservoirs and their plugging effect is closely related to particle size and diversion. In this paper, carbonate outcrop cores with artificial fractures are used to simulate heterogeneous fracture reservoirs, and the water plugging evaluation and improvement experiments are carried out under the condition of 130 ℃ and 19.8\begin{document}$ \times $\end{document}10\begin{document}$ ^4 $\end{document} mg/L. The results show that the oversized PPGs or the excessive PPG-diversion in low-permeability fractures may aggravate the heterogeneity of fluid production, while the undersized PPGs are not suitable for the reservoirs with high water production strength. Therefore, we propose combining the curable resin-coated particles (CRPs) with PPGs to improve the water plugging performance. The CRPs form immobile packs in high-permeability fractures at reservoir temperature, which results in the larger breakthrough pressure gradients of the PPGs in high-permeability fractures relative to that of the PPGs in low-permeability fractures. The combined CRPs and PPGs can reverse the liquid-producing profiles of the heterogeneous fractures and eliminate the negative effects of improper PPG size and diversion rate on the water plugging. This study is helpful to further understand the water-plugging behaviors of PPGs in heterogeneous fractures and has positive significance for improving the water control effect in fractured reservoirs.

Key words: preformed particle gel, curable resin-coated particles, fracture, water plugging, heterogeneity