Different types of polymeric Drag-Reducing-Agents (DRA) have been used in liquid pipelines to overcome the capacity limitations and/or reduce the cost of utility by lowering the pressure drop. Optimum usage of DRA depends on how accurately pipeline operators can predict its drag reduction efficiency. The most widely used model in pipeline industry for predicting the drag reduction efficiency correlates drag reduction as a function of DRA concentration alone. However, in reality drag reduction can be significantly different from the predicted one depending on the variations in operating conditions and flow geometry.
This work is an attempt to provide a conceptual framework wherein the effects of operating conditions and flow geometry, expressed by Reynolds number, and polymer concentration on drag reduction are quantified. The proposed model has been validated over a wide range of operating conditions, DRA concentrations and pipe diameters for two types of commercially available DRA fluids using field test data. Overall, the proposed model gives an excellent reduction in the variability of drag reduction as a function of respective regressor variables.
The concept of polymeric drag reducing fluids was introduced in the oil industry as early as 1946; however, its commercial application was not practiced till about 30 years later in the Trans-Alaska pipeline system where the capacity of the pipeline was increased from 1.4 to 2.2 million barrels per day solely by using DRA. Nowadays, different types of drag reducing products are commercially available and pipeline operators benefit from DRA to increase the pipeline capacity and/or reduce the cost of utility by lowering the pressure drop, globally. In some cases the drag reduction is so dramatic, that pipeline operators are able to shutdown selected pump stations without any noticeable drop in the overall throughput.
