Experimental investigation on plugging and transport characteristics of low-density preformed particle gels in fractured tight reservoirs for enhanced oil recovery

A novel low-density multistage expansion preformed particle gel (LDMPG) was synthesized to mitigate gas breakthrough. To investigate LDMPG's potential of fractures plugging and enhanced oil recovery, the structure, micromorphology, expansion property, and thermal stability were characterized, followed by core-flooding experiments. Experimental results indicated that hollow glass microspheres (HGMs) were grafted onto LDMPG through chemical modification and polymerization. The LDMPG can expand 30 times under formation conditions, while maintaining a density of 1.06 g/cm 3 . The temperature resistance can withstand up to 120°C, while the salt resistance can tolerate up to 200,000 mg/L. After 90 days of aging, the transition pressure and toughness coefficient were 107.9 KPa and 0.82, the retention rates were 81.9% and 85.4%, respectively. The core flooding experiments demonstrated that LDMPG can effectively plug fractures, thereby enhancing the oil displacement efficiency of the matrix by approximately 19%. All the results indicated that LDMPG had great potential in conformance control of fractured tight reservoirs.