Engineering and Technology Journal Vol. 37, Part A, No. 10, 2019 DOI: http://dx.doi.org/10.30684/etj.37.10A.2 Copyright © 2019 by UOT, IRAQ 391 Raheek I. Ibrahim Electromechanical Engineering Department, University of Technology, Baghdad- Iraq 80058@uotechnology.edu.iq Manal K. Odah Electromechanical Engineering Department, University of Technology, Baghdad- Iraq 50030@uotechnology.edu.iq Dhoha A. Shafeeq Electromechanical Engineering Department, University of Technology, Baghdad- Iraq dhohaahmad94@gmail.com Received on: 18/02/2019 Accepted on: 21/05/2019 Published online: 25/10/2019 An Overview on Most Effective DRAs in Crude Oil Pipelines Abstract- The flow of crude oil in pipelines suffers from a problem of fluid flow pressure drop and high-energy consumption for pumping especially in low temperatures environment. Flow can be enhanced using viscosity either reduction or drag reduction techniques. Drag reduction is considered as the most effective and most applicable method. The technique contributes in reducing the frictional energy losses during the flow by addition of little doses of materials knowing as drag-reducing agents. The present work focuses on more recent and most applicable drag-reducing agents used in crude oil flow enhancement via pipelines. Keywords- Crude oil, Drag reduction, Flow enhancement, Fibers, Polymers, Nanomaterials. How to cite this article: R.I. Ibrahim, M.K. Odah, and Dh.A. Shafeeq, “An Overview on Most Effective DRAs in Crude Oil Pipelines,” Engineering and Technology Journal, Vol. 37, Part A, No. 10, pp. 391-397, 2019 1. Introduction When fluids are transported through a pipeline, a decrease in fluid flow pressure is usually occurres because of high friction involved between the wall of the oil pipe and the fluid. Because of this decrease in pressure inside the line, fluids are transmitted below suitable pressure to obtain the required productivity. In order to achieve desired flow rates across the pipeline, more pressure must be applied because with increased flow rates also increases the difference in pressure. However, there are limitations regarding pipeline design leading to reduce the amount of pressure that can be used. Problems associated with decreased pressure are compounded when fluids are transported over long distances. Such decrease leads to inefficiency thus increases the volume of equipment and operating costs [1,2]. To overcome the problems associated with low pressure, many industries use additive materials in flowing liquids. When the fluid flow in the pipeline is disturbed, it can be here used a material that is highly capable of reducing the losses resulting from the reduced flow pressure. The function of these additions is in suppressing the evolution of turbulent vortices resulting in an increase in flow rate under steady pumping pressure. It is known as polymers, fibers, surfactants and nano materials used as drag reducers operate especially in hydrocarbon fluids. Each type of drag-reducing agent (DRA) has diverse techniques to decrease the drag within the pipeline system. Although still efficiently founded, drag-reducing agents are thought to work in several ways like turbulence repression, expansion of laminar domain limit to maximum Reynolds Number, near wall flow modulation, and friction detraction in totally advanced turbulence flow [3-5]. The aim of the present review is to survey the studies relating to the methods of reducing the drag in the oil pipelines and review the materials that are used as efficient drag reducers. The working mechanisms of each material are also included. 2. Drag Reduction working Mechanism Drag reduction is known as a transport phenomenon where a tiny amount of additive material may reduce the friction factor of the fluid flow. The function is to increase the capacity, and decrease the power required for oil pumping through active agents, defined as Drag Reducing Agents (DRAs). Drag reduction (%DR) known as the ratio of pressure drop value  without additive to pressure drop value  with additive, as shown in Eq. (1) [5,7,8]. %         (1) Where ΔP is the pressure drop without drag reduction additives, and ΔP DRA is the pressure drop measured when using a drag-reducing agent. The working mechanism of DRA additives can be classified as: