Drag Reducing Agents (DRA) are widely used in liquid pipelines for enhancing pipeline capacity, primarily to fulfill peak seasonal product demand without the need for major CAPEX. In addition, DRAs are also used to reduce energy consumption, thereby reducing the OPEX. DRA chemicals work by reducing frictional pressure losses in turbulent flow.
To establish DRA performance, field tests are conducted usually by varying the DRA injection rates for a fixed flowrate. The recorded pressure drops(s) are compared with the base line pressure drop to generate the DRA performance curve. The DRA performance curve is used to extrapolate and estimate DRA dosage for target flowrates, or to predict the achievable flowrate. Field experience shows that the predicted DRA performance does not always match actual field performance and the estimated DRA dosage can be underestimated.
This paper presents two DRA application cases in refined product pipelines, in which the actual DRA performance achieved was lower than predicted. The causes for deviation were studied, and mitigations for meeting the target flowrates were proposed.
Saudi Aramco owns and operates vast network of crude, refined product and gas pipelines. Approximately 3,000 km (1,864 miles) of product pipelines provide a reliable supply backbone spread across all major population areas of Saudi Arabia. Another 2,500 km (1,553 miles) of new product pipelines shall be added in the next five years. These pipelines transport refined product from refineries to bulk plants located at all major cities in Saudi Arabia.
In terms of refined products i.e. Diesel, Gasoline, Jet fuel etc., there may be increased demand which is seasonal in nature. During summer, in Saudi Arabia, the demand for refined products increases significantly necessitating increase in refined product pipeline capacity. Saudi Aramco strategy is to use DRA as a cost-effective way to cater to these seasonal demand upticks while maintaining safe and reliable operations.