ABSTRACT

Pipelines are commonly used in the petroleum industry to extract and transport crude oil and natural gas from the petroleum reservoir to storage facilities. The flow kinematics of crude oil through pipelines is unsteady and is associated with a constant change in the viscosity of fluid. The effect of unsteady viscous flow is predominant at wall boundaries, where there exist relative motion between crude oil and pipe wall, acting in reverse direction. This fluid-wall interaction induces viscous drag at the wall boundary due to friction. When friction occurs, stress and heat will be exerted at the contact interface. Solid particles sourced from the unconsolidated nature of sandstone lithology are transported alongside with crude oil. These particles impinges on the pipe wall and erodes the corrosion resistant layer, thereby exposing the pipe surface to the corrosive fluid. This study is aimed at evaluating the impact of unsteady viscous flow and presence of solid particles on pipeline surfaces during crude oil transport. Identified areas with high viscous stress is important and this was achieved using CFD. The two equation k-ω turbulent model and particle tracing were used as the flow physics, to achieve the aim of this paper. It was established that the properties of crude oil had an influence on the estimation of wall viscosity and erosion rate. The numeric value of the selected fluid properties such as dynamic viscosity, specific gravity, and velocity was in the range 0.08 – 0.20 Pas, 0.66 – 0.93 and 20 – 60 m/s respectively. Regions with maximum contact with the moving fluid had the maximum viscous drag and frictional velocity predictions. This region was identified as the potential hotspot and located at the pipe elbow.

KEYWORDS

Unsteady viscous flow; Erosion rate; Crude oil transport.