Analytical evaluation of oil and water obtained from demulsification of crude oil using cashew (<i>Anacardium occidentale</i>) nutshell liquid

Abstract

The physiochemical characteristics of oil and water obtained from the demusifier treatment of crude oil using equal concentrations of Cashew nutshell liquid (CSNL) and a commercial grade demulsifier (DX077) were evaluated. Results obtained shows that basic sediment and water (BSW) of the crude after treatment with CSNL and DXO77 were 17.5 and 17.9 % respectively which was 0.4% apart. The total oil and grease (TOG) and total petroleum hydrocarbon (TPH) of the produced water after treatment with CSNL were 24.4 and 21.7 mg/l respectively while results after treatment with DXO77 were 23.7 and 20.5 mg/l respectively. The TOG and TPH of the produced water after demulsifier treatment with CSNL and DX077 were within acceptable limit of < 30.0 mg/l as specified by Department of Petroleum Resources (DPR). Analyses of the same crude oil before demulsifier treatment gave a lower BSW of 9.50 % as well as an emulsion band of 16.2 % indicating improper oil/water separation. The TOG and TPH of the produced water before demulsifier treatment were 42.5 and 38.7 mg/l respectively which were above DPR specification. Disposal of produced water with high TOG and TPH into the environment can lead to the release of volatile organic compounds (VOCs) into the ecosystem resulting in environmental pollution as well as other health hazards. Results obtained also show that the water density, pH, electrical conductivity, salinity and chloride of the produced water after demulsifier treatment with CSNL and DX077 were within DPR specification. Reinjecting produced water with high salinity, chloride and conductivity into the reservoir can reduce oil recovery especially from sandstone and carbonate reservoirs. CSNL proved to be an effective demulsifier and is preferrable to the synthetic demulsifier (DX077) because it is more environmentally friendly owing to its green nature.