Application of Phenolic Resin Crosslinked Polymer Gel in Fractured-Vuggy Carbonate Reservoir with High Temperature and High Salinity

Abstract

Abstract As a special unconventional reservoir, the high temperature and high salinity of fracture-vuggy carbonate reservoirs has been confining the advance of EOR technology. Take water plugging as an example, the majority of plugging agents currently do not have temperature and salt resistance at the same time. Therefore, a novel Phenolic Resin Crosslinked Polymer Gel (NPRG) which has excellent resistant to high temperature (140°) and ultra-high salinity (240000mg/L) reservoirs is going to be developed. In this paper, methenamine, hydroquinone, thiourea, cobalt chloride hexahydrate (CCH) are synthesized by certain mass ratio. Besides, rotational rheometer, SEM were used for characterization before and after gelation, plugging performance of gel was measured using cubic fractured core. The research found that, CCH can provide more crosslink points for the 3D mesh structure of bulk gel system. Therefore, the period of dehydration of gel microstructure was extended. The initial viscosity was 77.1mpa·s when this bulk gel system achieved its optimal concentration ratio, besides, the dehydration rate of this bulk gel system is only 5% within 30 days and its strength can be stabilized at H-I level within 150 days. The NPRG also has a satisfactory shear resistance performance and a better erosion resistance. Additionally, result of core flooding experiment showed that NPRG achieve a plugging rate of 90% and has little damage to the substrate. Finally, the success of laboratory experiments and pilot tests indicates that NPRG has certain application potential in fracture-vuggy carbonate reservoirs where fractures are dominantly developed.