Improving Heavy Oil Production Using Viscosity Reducers

Abstract

Abstract Chemicals for viscosity reduction play an important role in improving heavy oil production amongst other more commonly used technologies, such as crude oil heating by steam, and oil dilution with solvents. The viscosity reducer is able to dissolve in aqueous solutions, which makes it easy to handle and implement in wellbore lifting, huff-n-puff or well-to-well injection. In this work, eleven heavy oil viscosity reducers originally in emulsion form were investigated against a degassed conventional heavy oil with a viscosity of 246 mPa.s at 60°C. They were evaluated in terms of compatibility with high salinity water, interfacial tension, static adsorption onto carbonate core powders, viscosity reduction, micromodel displacement, and coreflooding displacement. The viscosity reducers present respectively either excellent or good compatibility with a high salinity brine of 57,760 mg/L total dissolved solids (TDS). The slight difference in compatibility did not affect wate/oil interfacial tension but affect significantly the static adsorption onto carbonates. Significant heavy oil viscosity reduction was observed when mixed with 2 wt% viscosity reducers at a water-cut of 30%. Among eleven viscosity reducers, one reduced the viscosity by 82%, three by 60% to 70%, four by 50% to 60%, and three by 25% to 50%. Micromodel displacement presented consistent trend in oil recovery, ranging between 10% and 50% beyond waterflooding. Coreflooding displacement showed that the selected viscosity reducer (HOVR10) in solution increased heavy oil production by 20.3%. Efficient viscosity reducers provide an economical way to improve heavy oil productoin. They would reduce the energy consumption in producing heavy oil from the subsurface formation to surface facilities. As such, the application of heavy oil viscosity reducer would not only improve well productivity but also reduce operational costs.