Stability Study of Some Selected Nigerian Crude Oil Emulsions and the Effectiveness of Locally Produced Demulsifier

Abstract

Crude oil emulsion stability causes high viscosity of crude oil which leads to problems in pipeline transportation and processing. In this research, four samples of crude oil emulsions were collected from Ughelli East Wellhead and labeled A, B, C and D. These samples were characterized to determine their specific gravity, ⁰API gravity, structural composition, density, temperature, amount of water, amount of gas and the gross crude oil production. The ⁰API at 60 ⁰F showed that all the samples had values below 30 ⁰API which was an indication that the crude oil produced from these wells were heavy crude oil. The FTIR spectra showed bands at 3444.55 cm^-1 for Sample A, 3418.23 cm^-1 and 3175.94 cm^-1for Sample B, 3444.61 cm^-1 for Sample C and  3444.49 cm^-1 for Sample D attributing to strong and broad O-H stretch, H-bonded and an indication of Asphaltenes presence; the alkanes signal, C-H stretch at 2961.14 cm^-1 for Sample A, 2926.00 cm^-1 for Sample B, 2924.15 cm^-1 for Sample C and 2922.88 cm^-1 for Sample D are indications of the presence of wax; C=O stretch at 1737.74 cm^-1 only present in sample C is an indication of the presence of resins. The well test details showed that sample A and B had smaller water percentage in the gross crude oil production than Sample C and D with high water percentage. Therefore crude oil produced from these four wells represented by samples A, B, C and D contains natural emulsion stabilizers and stable. However, the stability of Samples A and B are more than that of Samples C and D. The performance of locally produced demulsifier increased with increase in residence time of contacting it with the emulsion samples at their operating temperatures, while equal dosage of patent Separol N46 demulsifier showed no performance within thesame residence time. However, treatments A_WHT, B_RT, C_WHT and D_WHT all at well head temperatures of 35.6 ⁰C, 27 ⁰C, 48.2 ⁰C and 48.8 ⁰C respectively showed that most water was expelled in 480 minutes.

Key words: Stability, Selected, Crude oil, Emulsion, Demulsifiers, Treatment