Palm oil fuel ash (POFA) as a demulsifier for crude oil emulsions: Performance and mechanism

Abstract

The petroleum industry is greatly in need of smart and cheap demulsifiers to break heavy crude oil emulsions. This study investigates the performance of palm oil fuel ash (POFA) as a demulsifier of crude oil emulsions produced during hydrocarbon exploration. Highly stable water-in-oil (W/O) emulsions having water:oil ratio of 7:3 were prepared under room temperature (25 °C) at a mixing speed of 1500 rpm. Demulsification performance of various concentrations of POFA (1 wt% to 9 wt%) was performed using the bottle test method at 60 °C and 80 °C. Experimental results show that POFA can effectively break the emulsion and separates water/oil into phases. The emulsion containing 3 wt% POFA exhibited the highest water/oil separation with demulsification efficiencies (DEs) of 99.28% and 99.71% at 60 °C and 80 °C, respectively. Additionally, a comparison between POFA and a commercial demulsifier (poloxamer - 407) showed that POFA can compete favorably with demulsifiers regularly applied in oil fields. Optical electron microscope analysis revealed the morphology of water and oil phases after emulsion separation. Results from the rheological measurements established the capacity of POFA to be able to destabilize the natural emulsifiers existing at the water/oil interface. Interfacial tension results show that POFA particles have a strong tendency to diminish the water/oil interfacial films. An investigation of the demulsification mechanism reveals that silica in POFA plays a critical role in the breaking of stable crude oil emulsions. Certainly, POFA will be a promising demulsification material for separating or removing water from all forms of emulsions produced in the oil fields.