Enhancing Demulsification of Water-in-oil Emulsion by Eliminating Trace Value of Percentage Residual Water
Jude D. Inyang *
Department of Chemical and Petroleum Engineering, University of Uyo, Uyo, Nigeria.
Julius U. Akpabio
Department of Chemical and Petroleum Engineering, University of Uyo, Uyo, Nigeria.
Benjamin R. Etuk
Department of Chemical and Petroleum Engineering, University of Uyo, Uyo, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
The elimination of residual free water and Basic Sediments (BS&W) after field demulsification process and characterization is being investigated with a diluent, to enhance field treatment for quality assurance and crude oil custody transfer. The American Standard for Testing Materials (ASTM) D 4007 is used as separation technique for three field emulsion samples from two Niger Delta basin oil facilities. After an initial bottle test, free water content in crude oil samples on arrival were 0.65%, 0.70% and 0.55% for samples A, B and C respectively. Tests and analysis were carried out at room temperature of 28°C and a water-bath temperature at 60°C. Maximum water separation efficiency of 91% was achieved at diluent and emulsion concentration ratio of 1:9 in first 60 minutes to 720 minutes. BS&W reduced from an average of 0.6% to 0.25%. Emulsion separation index (ESI) provided emulsion stability measurement of respective samples with a contrast between static-laboratory and field-dynamic conditions. From the study, sample B has API of 39 and ESI=40 while recording greater separation than in A and C crude oil samples. Hence, separation efficiency increased with the amount of xylene added and free water percentages reduced in top dry oil with significant changes in BS&W.
Keywords: Stability, water separation efficiency, emulsion separation index, demulsification, custody transfer.