Studying the Effect of Some Surfactants on Drag Reduction of Crude Oil Flow

The influence of SDBS, SLS, SLES, and SS as drag reducing agents on flow of Iraqi crude oil in pipelines was investigated in the present work. The effect of additive type, additive concentration, pipe diameter, solution flow rate, and the presence of elbows on the percentage of drag reduction (%Dr) and the amount of flow increases (%FI) was addressed. The maximum drag reduction was 55% obtained at 250？ppm SDBS surfactant flowing in straight pipes of 0.0508？m？I.D. The dimensional analysis was used for grouping the significant quantities into dimensionless groups 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 the correlation coefficient. 1. Introduction Drag reduction is a phenomenon in which the friction of a liquid flowing in a pipe in turbulent flow is decreased by using a small amount of an additive. The used drag reducing additives are effective because they reduced the turbulent friction of the solution. This resulted in a decrease in the pressure drop across a length of the pipe and likewise reduced the energy required to transport the liquid [1]. Surfactants are one of the most important drag reducing agents, which have the ability to form a certain structure called micelles. The important aspect of surfactant which impacts their performance is their ability to self-repair. This is the ability of a group of molecules to return to its original form after their structure has been altered as a result of high shear; this property recognizes the surfactant from polymers and aluminum disoaps, which degrade when subjected to high shear and generally cannot reform. Therefore, they cannot be effective in recirculating the fluid, and these pumps apply high shear stress to fluid. This causes the polymer chains to break into small segments which do not have the ability to revert to their original form. On the other hand, surfactants are able to repair themselves in a matter of seconds upon degradation of shear. This characteristic makes surfactants a good candidate for recirculation systems [2]. The mechanisms by which these agents work (turbulent suppression; extension of laminar behavior to abnormally high Reynolds numbers; or wall layer modification, reduction of friction in fully developed turbulence) are not defectively established, but they are believed to inhibit the formation of microscopic eddies in the liquid [3]. The goal of the present work was to investigate the validity of the effectiveness of SDBS, SLS, SLES and SS (concentrations