Hydrogel enhancement at high temperature by graphene oxide interface reaction with polyacrylamide

Abstract

To migrate the gel degradation at high temperature oil and gas reservoir conditions, nano sized graphene oxide (GO) was composited in polyacrylamide (PAM) first, which was then reacted with organic crosslinker to fabricate the enhanced hydrogel. Based on the results of ATR-IR (Attenuated Total Reflectance Infrared Spectroscopy) and XPS (X-ray Photoelectron Spectroscopy), GO was successfully compounded in the gel and H bonding attributes to the main interaction between functional groups on GO surface and the polymer chains, which provides more potential physical cross-linking points. To evaluate the mechanical strength of gel samples, rheological property measurement and breakthrough pressure test were carried out. The results showed that at elevated temperature conditions, the incorporation of GO onto polymer chains can enhance the strength of hydroquinone (HQ)–hexamethylenetetramine (HMTA) crosslinked polymer gel, while it exhibited adverse effect on polyethyleneimine (PEI) crosslinked gels. TG test results also showed better thermal stability of HQ-HMTA crosslinked gel. SEM images showed that HQ-HMTA crosslinked composite gel has more tight network structure than that without GO. The influence of HQ-HMTA concentration, temperature, and water salinity were investigated. Even at temperatures over 130 °C or at maximum salinity of 20 %, no significant reduction of gel strength occurred. GO enhanced hydrogel can be considered as a promising material for plugging at severe reservoir conditions of high temperature and high salinity.