LAUSR

The present crippling crude oil price worldwide demands a new strategy and cost-effective technology that will promote additional oil recovery in mature oilfields. Herein, crosslinked polyacrylamide (PAM) gels reinforced with coal fly ash (CFA) were investigated for water reduction purpose during enhanced oil recovery. Polyethyleneimine (PEI) is chosen as the crosslinker. Neat PAM/PEI gel and PAM/PEI composite gels filled with various CFA concentrations (0.5 to 2 wt%) were developed and characterized by aging, gravimetric, hybrid rheometer, thermogravimetric analyzer (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) instruments. Gelation performance of these gels was conducted at 90 °C, and results show that increase in CFA in PAM/PEI gels causes a delay in the gelation time. This indicates that CFA can act as a retarder in polymer gels applied for water control in mature oilfields. Moreover, the PAM/PEI composite gels containing CFA displayed improved viscoelastic properties as compared to the neat PAM/PEI gel at various gelation behaviors that were tested. Additionally, TGA analysis revealed that PAM/PEI gels infused with different CFA amounts possessed high resistance to thermal decomposition. The presence of alumina and silica in high concentrations in CFA induced a strong bond within these polymer gels, which resulted in improved thermal stability. Further, owing to the fact that CFA only absorbed a small amount of water through the hydroxyl and amine groups, its presence decreased the swelling ability of these composite gels. Morphological and structural analysis demonstrated by these gels affirmed the consistency of viscoelastic, thermal and swelling kinetic results. Copyright © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.