Synthesis and Performance of a Polyhedral Oligomeric Silsesquioxane-Based Viscosity Reducer for Heavy Crude Oil

In heavy crude oil reservoirs where thermal recovery is limited by geological or operational constraints, nano-assisted viscosity reduction has been increasingly recognized as a promising strategy to enable efficient cold production. In this study, a novel POSS-containing amphiphilic branched polymer viscosity reducer (HN-Z) based on nanoalkene polyhedral oligomeric silsesquioxane (POSS) was synthesized via free-radical polymerization using PSS-octavinyl POSS, hexadecyl dimethyl allyl ammonium chloride (C16DMAAC), allyloxy polyethylene glycol (APEG-8), and acrylamide (AM). Structural characterization indicates the successful incorporation of POSS nanocage units into an amphiphilic polymer framework, forming a POSS-containing branched nanostructured polymer. Performance evaluation using M138 heavy crude oil demonstrated that HN-Z exhibits excellent apparent viscosity reduction performance via emulsification, strong emulsification performance, and good adaptability to reservoir conditions. The reagent maintained high viscosity reduction efficiency in the presence of reservoir minerals and showed outstanding oil-washing ability as well as good universality for heavy crude oil from different oilfields. Compatibility tests and physical simulation flooding experiments further confirmed that HN-Z possesses good compatibility with polymer systems and can effectively enhance heavy crude oil recovery. These results indicate that the POSS-based viscosity reducer provides a promising strategy for improving heavy crude oil mobility in chemical-assisted cold production.