Nanocellulose-regulated robust particle-gel for conformance improvement in fractured tight reservoirs: A mechanistic investigation of transport behavior and EOR performance in fracture models

Owing to the interpenetration of high-modulus nanocellulose into polyacrylamide (HPAM), the mechanical properties of particle gel were substantially improved. Five transport patterns in fractures were demonstrated as defined by particle/aperture ratio. The pressure drop (ΔP) generated by nanocellulose-regulated particle gel (NPG) depended on particle/fracture ratio, followed by NPG content and strength. A numerical model was established to correlate the stable ΔP of NPG with four critical operating parameters. The placement of NPG significantly remedied the conformance of the fractured cores; therefore, the subsequent CO₂ and ultralow IFT surfactant injection processes produced additional oil recoveries of 4.7% and 7.1% original oil in place (OOIP), respectively, with the ultimate oil recoveries of 10.8% and 12.2% OOIP. However, the matrix oil was hardly mobilized during brine injection even after conformance treatment due to the adverse wettability and high capillary pressure.