Water Management and Oil Recovery Improvement Performance of High-Strength Preformed Particle Gels in Fractured Conglomerate Reservoirs

Lithologic reservoirs, such as conglomeratereservoirs, exhibitstronger heterogeneity compared with conventional sandstone reservoirs.Their early stage development usually requires hydraulic fracturingto increase the stimulated reservoir volume (SRV). As a result, high-conductivitychannels are generated during waterflooding, which further limitthe sweep volume and oil recovery. Traditional particle gels and insitu cross-linked polymer gels exhibit limited field application dueto their low plugging strength. In this paper, a high-strength preformedparticle-gel (HSPPG) with sticking-together capability wasstudied through evaluating different factors such as particle size,swelling ratio, injection volume, and their effects on the swellingperformance, gel strength, and plugging performance in fractures.The results show that the swollen HSPPGs had strong water swellingand sticking-together ability, exhibited good viscoelasticity, andformed high-strength adhesive bonds on rock surfaces. In addition,as the particle size decreased, the gel's maximum swellingratio increased. However, as the swelling ratio of HSPPG increased,the storage modulus G & PRIME; and the loss modulus G & DPRIME; both decreased, but they still displayed excellentelasticity and viscosity. The greater the filling volume of HSPPGin fractured conglomerate rock cores, the stronger the overall pluggingefficiency. Oil displacement experiments showed that the oil recoveryof fractured conglomerate rock cores treated with HSPPG increasedby 22.12 percentage points on the basis of primary waterflooding.Therefore, HSPPG has a promising application prospect in the conformanceimprovement of strong heterogeneity conglomerate reservoirs.