International Journal of Applied Engineering Research ISSN 0973-4562 Volume 12, Number 13 (2017) pp. 3576-3589 © Research India Publications. http://www.ripublication.com 3576 Pressure Drop Measurements of Oil (D80)-Water Flow in 6” Horizontal and Inclined Annulus Pipe Mehaboob Basha 1^ , Syed. M. Shaahid 1 , A. Ahmad 1 , A. M. Al-Sarkhi 1 ,Luai M. Al-Hadhrami 1 Mujahid O. Elobeid 1 J. J. Xiao 2 , Rafael Lastra 2 , Chidirim E. Ejim 2 1 Centre for Engineering Research- Research Institute, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia. 2 Saudi Aramco Dhahran, Saudi Arabia 1 ^Orcid: 0000-0001-5862-9117 Abstract The flow of two immiscible liquids (such as oil and water) in pipes is a challenging subject that is rich in physics and practical applications. It is often encountered in many oil and chemical industries. The pressure gradient and flow patterns of immiscible liquids are still subject of immense research interest. This is partly because fluids with different properties exhibit different flow behaviors in different pipe’s configurations under different operating conditions. More importantly, oil-water annular flow (oil surrounded by water) is a common occurrence in oil upstream petroleum industry and is generally used for the lubricated transportation of highly viscous oil. However, despite their importance, behavior of such flows has not been explored to an appreciable extent. The present study reports pressure drop measurements of oil (D80)-water annular two-phase flow in a horizontal and inclined 6 inch diameter stainless steel pipe at different flow conditions. Experiments were carried out for different inclination angles including; 0°, 40°, 60° 90° and for different water cut (WC) ratios. Water cut ratios were varied from 0 to 100% in steps of 20 %. Inlet oil-water flow rates were varied from 2000 to 12000 barrels-per-day (BPD). For a given flow rate (for all angles) the frictional pressure drop has been found to increases from WC = 0 to WC 40 %. Further increase in WC, friction pressure drop has been found to decrease. In general, frictional pressure drop increases with flow rate and water cut and the effect of angle was not appreciable. The behavior of total pressure was asymptotic with increase in flow rate. Also the behavior of total pressure was linear with respect to WC up to 80%. Keywords:Multiphase flow, Oil-water flow, Pressure drop, water cut, inclined pipe, annular flow. INTRODUCTION Heavy oils represent about one third of the world hydrocarbon resources, but, their production is associated with huge costs of transportation. Oil and water are often produced and transported together in pipelines that have various degrees of inclination from the horizontal. A possible transportation technique is core-annular flow (CAF). In this configuration, the oil flows at the center of the pipe (core) and the water flows as an annulus around it. Also, the widespread occurrence of multiphase flows in pipes has motivated extensive research (a number of upstream practical applications in the petroleum industry involve oil– water annular two-phase flow phenomena). Significant savings in the pumping power required for oil transportation (water-lubricated transportation of crude oil) can be attained when water flows in the pipeline together with the oil, especially when the highly viscous phase is surrounded by a water annulus, giving place to the core annular flow configuration. As the establishment of a particular flow regime depends upon the interaction of gravitational, inertial and surface tension forces, annular flow is observed only under particular combinations of the oil and water flow rates. Moreover, knowledge of the friction loss in oil-water flows in pipes is essential in order to specify the size of the pump required to pump the emulsions. The measurement of phase flow rates is of particular importance for managing oil production and water disposal and/or water reinjection. Pressure is the key parameter for assessing individual phase (oil and water) flow rates in annular pipelines. Therefore, it is important to study behavior of pressure response to characterize two-phase annulus flow in upstream production pipelines. Several articles are available in literature on the two-phase flow of oil and water in pipes. Kokal and Stanislav [1] calculated the pressure drop and liquid holdup for intermittent two phase flow in upward