A Novel Chemical Formulation for Heavy Oil Viscosity Reduction and Heavy Oil Displacement

Abstract

AbstractA novel water-soluble viscosity reducer (VR) formulation containing various polyaromatic hydrocarbon structures was designed for effective heavy oil viscosity reduction and heavy oil production by oil displacement. This VR package contains several components, including aromatic groups attached short-chain water-soluble polymers which were synthesized in laboratory, small-molecular aromatic chemicals, non-ionic and cationic surfactants, and rheology modifiers. The designed VR formulation was compatible with the high-salinity water (HSW) using appropriate preparation procedures. The VR solution in HSW yielded a stable emulsion after mixing with heavy oil and the emulsion phase separated subsequently, indicating a good performance in demulsification. The formulation decreased the viscosity of heavy crude oil by 84.2% at a temperature of 50 °C, a VR concentration of 0.2 wt%, and an oil-to-water ratio of 7:3. Micromodel test indicated that the residual oil blocks were effectively replaced by the VR flooding due to the strong emulsification and increased sweep efficiency by heavy oil viscosity reduction. The injection pressure decreased by the VR flooding due to a reduced viscosity of the heavy oil. The initial water injection increased the heavy oil production by 15% only, while the following VR flooding further enhanced the heavy oil production by 26% and the post water injection exhibited a limited effect on enhanced oil production by 4%, as obtained from the core-flooding test using a heavy oil saturated carbonate core.