Abstract

The influence of polyacrylamide (PAM) as drag reducing polymer on flow of Iraqi crude oil in pipe lines was investigated in the present work. The effect additive concentration, pipe diameter, solution flow rate and the presence of radius elbows on the percentage of drag reduction (%Dr) and the amount of flow increases (%FI) were the variables of study. Maximum drag reduction was 40.64% which was obtained with 50 ppm of PAM polymer flowing in straight pipes of 0.0508 m I.D. The dimensional analysis was used for grouping the significant quantities into dimensionless group to reduce the number of variables. The results showed good agreement between the observed drag reduction percent values and the predicted ones with high value of correlation coefficient.

Introduction

A spectacular reduction in energy losses in turbulent flows can be achieved by the addition of small amounts of certain polymers. Polymer drag reduction is due to the large elongational viscosity of the polymer solution; this stabilizes the turbulent boundary layer, leading to less turbulent energy generation and hence less dissipation [1]. Drag-reducing polymer solution flows behave like viscoelastic characteristics. The most notable elastic property of the viscoelastic polymer solution is that stress does not immediately become zero when the fluid motion stops, but rather decays with some characteristic time (the relaxation time), which can reach seconds and even minutes. It is generally believed that the frictional drag reduction caused by polymer and surfactant additives in a wall-bounded flow is the consequence of the interaction between viscoelasticity and turbulence in the flow. In a cationic surfactant solution, rod-like micelles can be formed if the surfactant/counterion chemical structures, molar ratios, concentrations, and temperature are under right conditions. This network microstructure imparts viscoelasticity to the solution flow, which was often stated to be responsible for the occurrence of Dr[2], [3]. Polyacrylamide is a high molecular weight water soluble polymer that used to improve flow. It is used to reduce energy and friction losses and can also be called friction reducers. Water can be injected to simulate oil production. The spontaneous flow of oil and water in crude petroleum production and transportation pipelines is a common occurrence, seen anywhere from the well perforations to the final stages of separation. The goal of the present work was to investigate the validity of the effectiveness of polyacrylamide (PAM) as drag reducing agent with Kirkuk crude oil. Also the effect of additives concentration, pipe diameter, solution flow rate and the presence of radius elbows on the percentage of drag reduction (%Dr) and the amount of flow increases (%FI) were the variables of the study.