Document Type : Research Paper



2 Department of Pure and Industrial Chemistry. University of Port Harcourt



The Asphaltene and metal naphthenate components of crude oil samples from ten different wells within an oil reservoir were determined using different analytical techniques. The asphaltene content was determined by gravimetric analyses while the metal naphthenate components were determined by obtaining the metal ion concentration of the produced water and the naphthenic acid concentration of the crude using Atomic absorption spectrometer (AAS) and potentiometric titration respectively. Results obtained showed that the asphaltene content of the crude samples ranges from 2.0000 – 8.000 %w while the naphthenic acid concentration indicated by the total acid number (TAN) ranges from 0.3000 – 1.4600 mg/KOH/g. All the crude samples possess asphaltene components as well as the propensity to form calcium and sodium naphthenate scale deposits having a Ca2+ concentration between 32.5000 – 94.5000 mg/L and a Na+ concentration between 27.7 – 105.1 mg/L respectively, however the formation of naphthenate scale deposits is highly dependent on the pH of the produced water of the crude which makes well FT01 less likely to form naphthenate scales since it has a pH < 6. Both asphaltene and naphthenate deposits are directly proportional to the specific gravity of the crude and inversely proportional to the API gravity implying that both components reduce the quality of the crude. Asphaltene and metal naphthenate solid deposits in the crude can cause a lot of flow assurance difficulties such as, blocking of expedition lines, pore plugging, wettability, crude oil parameter alteration, as well as reduction in oil recovery.


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