Polymetric drag reduction application techniques become more and more popular for energy optimization and carbon reduction initiative in the midstream industry. It is a challenge to reasonably predict and estimate the polymetric drag reducing agent (DRA) performance in various pipeline system planning, operations, and optimizations. A constant DRA performance curve may not be applicable for different liquid flow conditions. Scientific research and operation observations have proved the DRA degradation is unavoidable.
This paper discusses the use of the shear stress-based analysis approach to predict the DRA degradation performance in real operational scenarios for different fluid properties (viscosity, density, wax, and other impurity contents), pipeline characteristics (diameter and length), sudden fitting minor frictional losses and flow rates. The maximum drag reduction empirical formula based on Virk’s asymptote theory is generated as preliminary drag reduction potential assessment. Some rules of thumb formulas are provided for drag reduction gain and loss calculations as practical references. When the shear stress acting at the pipe wall exceeds a specific threshold, the DRA behavior is depicted as the pseudo steady-state condition, in which the time variable will be introduced to define a kind of dynamic drag reduction phenomenon. The presentation will discuss this DRA performance prediction method, rationale, and key findings.
The drag reduction behavior is influenced by many parameters. Different DRA manufacturers own unique product operation process design to improve their product quality. Different active ingredient polymer types (flexibility, molecular weight, chemical composition) are selected and designed specifically for different streams flowing in pipes. While the DRA product quality is controlled by manufacturers, customers are still facing some challenges to better understand DRA application in their properties.
Firstly, The types of liquids in pipelines are complex and need to be categorized. Liquid pipelines typically are used for the transportation of heavy crude, medium crude and light crude. Light crude may include extra light crude with or without wax content. The refinery products (gasoline and diesel) are classified as lean, relatively pure, and light liquids.
Secondly, pipeline mechanical characteristics and throughputs will impact the DRA performance. Sometimes DRA products can perform better in large diameter pipelines with large throughputs than some small diameter pipelines. The magnitude of pipeline lengths and minor frictional losses will also impact DRA overall performance.
DRA performance prediction is also important in pipeline capacity expansion projects. Sometimes unrealistic capacity estimations are generated per inaccurate DRA performance predictions.
