Synergistic Enhancement of Partially Hydrolyzed Polyacrylamide and Treated Palm Oil Fuel Ash for Enhanced Oil Recovery

Abstract Polymer flooding, a widely adopted technique for enhanced oil recovery, often relies on partially hydrolyzed polyacrylamide (HPAM). Despite its proven efficacy, HPAM faces challenges in hightemperature, high-salinity reservoirs. To address these limitations, this research explores the utilization of palm oil fuel ash (POFA), a byproduct generated from burning palm fibers and shells for electricity in mills. This sustainable additive aims to enhance the thermal stability, salt resistance, and mechanical robustness of HPAM. Laboratory experiments were conducted to evaluate the feasibility of incorporating POFA alongside HPAM, with a focus on cost-effectiveness and environmental friendliness. This study marks the pioneering utilization of POFA as an additive, introducing an innovative solution to mitigate the shortcomings of HPAM and advance polymer flooding efficiency in challenging reservoir conditions. POFA underwent washing, drying, grinding, and sieving to produce untreated POFA (UPOFA), followed by treatment involving heating at 900°C for 120 minutes to obtain treated POFA (TPOFA). Both ashes were characterized by means of particle Size Analysis (PSA), Zeta Potential (ZP), Fourier transform infrared spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray Analysis (EDX), and Thermogravimetric Analysis (TGA). Rheological properties, wettability, Interfacial Tension (IFT), and flooding experiments were conducted to assess the impact of adding both ashes to HPAM and a polymeric solution. The characterization results reveal a 1.6% enhancement in specific surface area for TPOFA, improved zeta potential by 8%, altered vibrational spectra, transformed surface morphology, and enhanced chemical composition post-thermal treatment. Rheological testing showed superior stability for HPAM/TPOFA, exhibiting robust intermolecular interactions. HPAM/TPOFA improved wettability and provided stronger water-wetting. Also, the novel mixture exhibited superior stability at elevated temperatures (up to 80°C), and high salinities (30,000 ppm) compared to pure HPAM. This enhanced stability could be attributed to strong intermolecular interactions between HPAM and TPOFA molecules. TPOFA effectively reduced IFT at the crude oil-water interface, and in oil displacement experiments, HPAM/TPOFA achieved the highest recovery (65% OOIP), showcasing its potential as an effective additive for EOR processes. This innovative hybrid of HPAM/TPOFA is designed to address the shortcomings associated with HPAM and improve its performance in challenging reservoir conditions using renewable resources.