Produced Water Debottlenecking Delivers Low Cost Incremental Production for the Pyrenees FPSO

Abstract

The Pyrenees FPSO development, located offshore Western Australia, produced first oil in 2010. By 2017, the topsides facility had became constrained by produced water production, reaching the facility design capacity of 110,000 bbl/d. A strong business driver was presented to debottleneck the water processing train to increase oil production, for which a holistic, system-wide approach was required. A series of brownfield debottlenecking scopes were identified and assessed using a systematic value versus risk approach. The key value drivers were recognised as incremental oil production, execution timing and cost. The assessment focused on improving Produced Water Re-Injection (PWRI) pump throughput and uptime, optimising the produced water treatment and overboard discharge systems, and the use of cargo oil tanks for separation. Project execution was phased to allow early debottlenecking gains to be unlocked as major modification scopes were progressed. The most capital intensive project executed was the installation of a side-stream Compact Flotation Unit package to polish and discharge produced water overboard. In combination, the projects delivered a 36% increase in produced water handling capacity to 150,000 bbl/d, accelerating 8.5% production over a 3-year period. In addition, the projects increased facility uptime by 1.8% and reduced the risk of late-life produced water injection system failures. This case study illustrates a logical and systematic approach to production debottlenecking, resulting in a significant production uplift, safely delivered for low relative CAPEX investment. The processes described and lessons learned in this project may be applicable to other maturing fields and facilities, and can be used to assist resolving late-life produced water challenges.