InSitu PolymerGel forHigh-SalinityWaterControl in Sandstone: Formation,Rheology, andThermal Stability

Gels generated in situ within porous media, despite serving as
non-selective blockers, constitute valuable options for managing
water in oil-producing wells while minimizing the risk of formation
damage. Accordingly, this study involved the preparation
of gel formulations employing an ionic terpolymer and crosslinkers
such as hexamethylenetetramine and resorcinol. The gels
formed in the presence of brine with salinity of 250,000 ppm
were classified as rigid according to the Sydansk scale. They
were identified as chemical gels through rheological analysis.
Furthermore, these gels demonstrated thermal stability at 160 °C,
over up to four months. The in situ-formed gels within porous
media exhibited fluid control efficiencies exceeding 96% in both
homogeneous and fractured rocks, as exemplified by sandstone
cores, following secondary oil recovery processes. This was
achieved using brine with salinity of 250,000 ppm (comprising
150,000 ppm NaCl and 100,000 ppm CaCl2) as the displacement
fluid at 130 °C.