Application of Enhanced Gel Strength Concept for PPD Chemical Optimization in Banyu Urip Export Pipeline

Abstract

Abstract Banyu Urip crude contains 26% wax which can provide flow assurance (FA) challenges in a stabilized crude pipeline exposed to lower temperatures. Injection of Pour Point Depressant (PPD) chemicals has widely been considered as an effective method to ensure flow assurance for moderate waxy crude. For the Banyu Urip field in Indonesia, PPD injection was compared to other methods and found to be the best option from a cost and operability perspective. Nevertheless, it still contributes to almost 20% of Banyu Urip operating costs. Optimization of this chemical usage brings benefit both for the Operator and also for the government through lowering operating costs. In the past, the flow assurance of waxy crude was determined by measuring \Pour Point (PP) temperature. At temperatures below this PP, the crude will stop flowing. PP measurement has several limitations, including providing a lower representation of the actual conditions. In this paper, a restart pressure simulation model and pilot experiments were used to provide a more realistic condition assessment and helped to avoid over-injection of PPD. In the enhanced gel strength concept, a weak waxy crude gel may be formed in the pipeline below its PP and still be breakable by applying pressure within the pipeline's Maximum Allowable Working Pressure (MAWP). Furthermore, the size of pipeline and the wax's natural insulation capability provides a radial temperature profile which can prevent the core pipeline from seeing a rapid temperature reduction. A pilot experiment for establishing a radial temperature profile has been conducted in by the Operator leveraging local university support. The same approach will be conducted for an upcoming flow loop experiment for restart pressure validation. In Banyu Urip, the initial PP target was set at 24°C based on the lowest seabed temperature observed in the offshore section of the pipeline. This target resulted in a PPD injection dosage of ~500 ppm. Using the enhanced gel strength concept, the required PPD injection rate was reduced to ~300 ppm. Further reduction is expected after conclusion of the radial temperature profile and flow loop experiments.