Addressing Detrimental Effect of Water Emulsion to Pour Point Depressant Application While Managing Fit-For-Risk Wax Mitigation in Banyu Urip Field

Abstract

Abstract High wax content characteristic of Banyu Urip (BU) crude is mitigated by continuous Pour Point Depressant (PPD) injection at multiphase stream. PPD treatment aim to lower Pour Point to 24°C with dosage of 475 ppm. It was observed that PPD dosage started to increase up to 650 ppm. This caused significant incremental cost as PPD accounts for 10% of total field OPEX. This paper shares rigorous troubleshooting method for resolving PPD performance degradation due to higher water cut. To optimize the PPD dosage while ensuring that the wax or crude gelling risk can be well mitigated, following activities were undertaken: [1] Critical parameters data collection and root cause analysis; [2] Formulation of solution to address the root cause; [3] Trial at laboratory scale as the early proof of concept toward the proposed solution; [4] Risk assessment that includes thorough analysis of crude gelling in each pipe section and mitigation required; [5] Field testing and monitoring. As the Banyu Urip field mature, the water cut increases more than double in a year. This condition creates water emulsion that has a detrimental effect on PPD effectiveness. Redistributing PPD injection from multiphase stream at well pad to dry crude stream at inlet export pipeline is deemed necessary to mitigate such issue. Detail review was conducted to assess the risk of reducing PPD dosage at well pad to processing facility especially during unplanned shutdown. Force balance equation was utilized to calculate minimum allowable gel strength in each pipe sections considering different pipe dimension, available pressure in the system, and temperature cool-down profile. Section which has the lowest minimum allowable gel strength and faster cool-down rate was used as governing case for PPD treatment strategy. The lab testing using artificial water emulsion homogenizer also performed to verify PPD effectiveness at different injection stream. This also gives an indication of required dosage and required pump injection capacity for the proposed scenario. The PPD redistribution field testing was then carried out with successful result of 175 ppm (~27%) dosage reduction by leveraging existing facility with fit for purpose approach. This paper provides insights how important the effect of water emulsion should be considered in the design phase, especially to stipulate PPD injection point location. This paper also provides guidance in determining PPD performance criteria using gel strength and pour point test with one-degree interval. Thus, operation strategy to mitigate crude gelling within a processing facility can be carefully developed.