Emulsification of Indian heavy crude oil and analysis of flow characteristics using computational fluid dynamics (CFD) for pipeline transportation

Abstract

The high viscosity of Indian heavy crude oils makes their pipeline transportation highly complicated and challenging. A huge pressure drop is observed while transporting heavy crude through pipelines. The present article addresses this complication by preparing a surfactant stabilized heavy crude oil-in-water (O/W) emulsion of a flowable viscosity to ease flow through pipelines. Different O/W emulsion samples were prepared with varying concentrations of a novel anionic surfactant, linear alkylbenzene sulfonic acid (LABSA), to achieve an optimized formulation based on rheological and stability studies. The article also discusses the effect of varying surfactant concentrations on interfacial tension, droplet size and distribution, and zeta potential of the developed emulsions. The optimized emulsion, having 60 vol% oil and 2 wt% surfactant, was further considered to simulate and analyze the flow characteristics (static pressure and velocity profiles) across the horizontal pipelines of three different inner diameters (0.1, 0.05, and 0.025 m) under three different inlet flow velocities (0.1, 0.05, and 0.001 m/s), using a computational fluid dynamics (CFD) approach. A remarkable decrease in the viscosity of heavy crude was noted after emulsification. Subsequently, the pressure drop across the pipeline was reduced significantly by order of three for the flow of O/W emulsion when compared to that of the heavy crude oil through a pipe diameter of 0.1 m at an inlet velocity of 0.1 m/s. The static pressure drop across the pipeline decreased with the increase in the pipe diameter; in contrast, it increased with the increase in the inlet velocity.