Study the influence of sodium dodecyl sulfate on emulsification of heavy and waxy crude oils to improve their flow ability in low temperature conditions

Abstract

Abstract Transportation of heavy and waxy crude oils through pipelines is a problem in many regions of the world where low temperatures are observed usually in offshore conditions due to wax and asphaltene precipitation. Transporting them as oil‐in‐water (O/W) emulsion through pipelines is one of the feasible flow assurance solutions. In this research work, O/W emulsions using anionic surfactant sodium dodecyl sulfate are prepared for two Indian crude oil samples having significant asphaltene and wax deposition potential and effect of emulsification on the flow properties of these crude oils are thoroughly analyzed. It is found that the prepared emulsions have very stable phase volume composition up to 50 days at ambient conditions, and they are thermally stable in the temperature range 20–45°C. Emulsions of heavy crude oil are found to be relatively more stable than that of waxy crude with time and temperatures. Fifty percent ( v /v) is the observed optimized oil content in the prepared o/w emulsions for both the crude oils at optimum surfactant concentration that is critical micelle concentration (CMC). The prepared emulsions have viscosities as low as 0.01 Pa s and pour point as low as less than 0°C, ensuring easy flow at low temperatures, suited for pipeline transportation at subsea conditions. Interfacial tension and surface tension values of waxy crude‐water system and its o/w emulsions respectively are higher than that of heavy crude‐water system and its O/W emulsions, which indicate difficulty in waxy crude oil transportation compared with heavy crude oil.