A novel hybrid hyperbranched nanowire CNTs for enhancing oil recovery through increasing viscoelasticity and high-viscous emulsions to compensate reservoir heterogeneity

Polymer flooding was one of the most cost-effective methods for enhanced oil recovery (EOR). It was the key for enhancing oil recovery that studying novel polymer could cope with harsh reservoir conditions. In this work, a hyperbranched nanowire (O-20 @PAM@CNTs) for polymer flooding was synthesized by in situ polymerization with monomers and hybrid carbon nanotubes (CNTs). FT-IR, 1 H NMR, TEM, gel permeation chromatograph (GPC) and rheometer were used to characterize the composition , micro-morphology, MWD (molecular weight distribution) and rheological properties of O-20 @PAM and O-20 @PAM@CNTs. Compared with O-20 @PAM, O-20 @PAM@CNTs showed excellent viscosification, temperature resistance, anti-shear and viscoelastic properties. The hyperbranched nanowire had the best performance with the content of hybrid CNTs of 0.2% w/w and which molecular weight (741999) was about half that of O-20 @PAM (1330629). Enhanced performance of the O-20 @PAM@CNTs could be attributed to the hybrid CNTs provided polymer a hyperbranched structure to build more compact and complex network and boost the association between polymer chains. Besides, the fatty alcohol polyoxyethylene ether(O-20) on the chains of O-20 @PAM@CNTs raised the viscosity of flooding liquid by emulsification and that partly compensated the heterogeneity of the core, thus improved the displacement efficiency markedly. Core Flooding Experiments shown that 0.3 times of pore volume O-20 @ [email protected] increased oil recovery by 17.5% contrasting only 11.6% for 0.4 times of pore volume O-20 @PAM, in the same solution concentration (2000 ppm). O-20 @PAM@CNTs had more obvious advantage in performance and more economical than O-20 @PAM, which indicated a better application of O-20 @PAM@CNTs in EOR.