Poly(acrylamide-co-acrylic acid) grafted graphene oxide for improving the filtration performance of drilling fluids

Abstract

An adequate drilling fluid filtration reduction additive should not only be able to minimize liquid leaking into the formation, but also be able to improve the applicability of drilling fluids in complex drilling conditions. In this study, polymer-grafted graphene oxide (GO) nanoadditives which could significantly improve the performance of drilling fluids are developed by surface modification of GO with charged polymer chains. The microstructures and compositions of the polymer-grafted GO nanoadditives are investigated with FT-IR, TEM with elemental mapping, ζ potential measurements, and TGA. Their performance as filtration reduction additives for drilling fluids is evaluated according to the American Petroleum Institute (API) standard. The results demonstrate that negatively charged poly (acrylamide-co-acrylic acid)-grafted GO nanoadditives are beneficial for water loss reduction in drilling fluids. The more negative charges on the surface, the higer the water loss reduction. This might be because the electrostatic repulsion between poly (acrylamide-co-acrylic acid)-grafted GO nanoadditives and bentonite particles slows down the formation of filter cake and make it denser, which slows down the penetration of water phase. Moreover, the results of filtration experiments under high salinity and high temperature conditions indicate that the addition of poly (acrylamide-co-acrylic acid)-grafted GO nanoadditives maintains the water loss reduction effect even at 180 °C or in fluids with 8 wt% NaCl. The presence of poly (acrylamide-co-acrylic acid)-grafted GO in the slurries could also improve their lubrication performance.