Adita Evalina Fitria Utami – 1206262765

Offshore pipelines consist of export pipelines and infield pipelines. Export pipelines transport oil or gas from either platform or FPSO (Floating Production, Storage, and Offloading) to beach for further processing. For single-phase flow, pressure drop is mainly controlled by the Reynolds number that is a function of the fluid viscosity, fluid density, fluid velocity, and pipeline size.

Multiphase Flow Concept

1. Superficial Velocity

Usl = liquid superficial velocityUsg = gas superficial velocityQl , Qg = liquid and gas volumetric flowrate, respectivelyAf = pipeline flow cross-sectional area

2. Mixture Velocity

Um = fluid mixture velocity

3. Liquid Holdup

Hl = liquid holdupVl = pipeline segment volume occupied by liquidV = whole pipeline segment volume

4. Gas Void Fraction

αg = gas void fractionVg = pipeline segment volume occupied by gas

5. Average Gas and Liquid Velocities

ul , ug = average liquid and gas velocity, respectivelyAl , Ag = pipeline cross-sectional area occupied by liquid and gas, respectively

6. Slip Velocity

Slip Velocity in Homogeneous gas and liquid 7. Water Cut

fw = water cutQo,Qw = oil and water volumetric flowrate, respectively

8. Mixture Density

ρm = gas-liquid mixture densityρl , ρg = liquid and gas density, respectively

9. Mixture Viscosity

μm = gas-liquid mixture viscosityμl , μg = liquid and gas viscosity, respectively

The liquid viscosity can be the viscosity of water, oil, or water-oil mixture. Normally, the water-oil mixture viscosity can be calculated based upon the water cut: