Effect of Temperature on Degradation of Polymer Drag Reduction and Heat Transfer in Non-Newtonian Fluid

Abstract

Abstract Drag reduction is a well known phenomenon. Possible mechanism deduced from heat transfer has been suggested earlier for non isothermal Newtonian fluid treated with polymer drag reducer. Several works have shown the susceptibility of the long chain polymer to shear degradation, hence reduction in its performance. Most of the works were performed in isothermal conditions. Moreover, it mostly covers water soluble polymers. There is an increasing need to address the shear degradation phenomenon for oil soluble polymer, where its performance is related to increase transportation capacity of pipeline as well as energy savings. In this work the degradation of oil drag reducing polymer in a non-isothermal environment in which rheological change of oil (the carrier fluid in this work) occurs as the fluid is transformed from Newtonian to non-Newtonian is addressed. In another words, the paper addresses the temperature effect on the degradation of the oil soluble drag reducer polymer in a wide range of temperatures. The non-Newtonian fluid behaviour here is defined as the temperature below which paraffin deposits in presence of drag reducer polymer. The validity of equations for estimating Colburn factor is also addressed. Introduction Degradation of drag reducer polymers has been reported in literature. Most of the reported works are for water soluble drag reducers1–7. Nowak 8 (2003) reported a negative influence of aged drag reducer surfactants, which was believed to be due to deterioration of chemical bonds in micelles with time. Moussa et al9(1994) studied the factors affecting polymers, polyacrylamide and polyisobutylene, degradation in turbulent flow. They suggested that most degradation takes place at the pipe entrance due to high extensional straining of polymer molecules. They also concluded that the pipe length did not seem to have much effect. The effect of temperature on degradation on water soluble DRA has been addressed in literature, however, to our knowledge, not for oil soluble drag reducer. Choi and Kasza10(1981) performed study on the degradation on a polyacrylamide solution at three different temperatures, ranging from 7.2 oC to 87,8 oC. They found that the polymer easily rupture at high temperature, and concluded that the degradation strongly depends on the temperature. In this paper, the effect of the temperature and temperature gradient on degradation of oil soluble DRA polymer (polyisobutylene) is investigated and it is extended non-Newtonian fluid behaviour. The solvent used here is crude oil from the North Sea. The validity of the colburn factor for Non-Newtonian, visco-elastic fluid is addressed in this work.