Production Sustainability Through Compressor Change-Out - Challenges & Lesson Learnt

Abstract Gas Hub A is located 170 km north of Bintulu in approximately 94.10m water depth comprising a drilling platform, bridge-linked to a processing platform and a compression platform. The initial average annual gas production was 500 MMscfd, with a capacity to produce at 600 MMscfd. Over the years since the first gas in 2003, gas production has been gradually reducing. In March 2018, an Improved Gas Recovery (IGR) study identified an opportunity to improve gas recovery from Gas Hub A by lowering the suction pressure of export compressor. This opportunity was to realise additional reserves of 213 Bscfd of gas and 3.0 MMstb of condensate. Operations decided to replace the current compressor from single stage to dual stage compressor and gradually reduce its operating pressure from 48 barg to 20 barg between 2021 and 2025. This will allow the hub to operate the gas wells at lower suction pressure through the compressor and maximise the reserve recovery factor. This will also prolong the field life and delay the cease of production by five years and ensure steady upstream production from other upstream sources and continue its role as production hub. This paper will address the challenges and solutions related to changing and operating the new centrifugal compressor system at site. It will cover how to adjust the suction pressure to meet the process needs at different production stages to increase the recovery and sustain the production level. It will also discuss the operational issues such as vibration monitoring, material compatibility and stability of the new operating envelope with varying inlet gas pressure and its effects on the machine performance. The performance and reliability of compressors is a critical task and requires continuous monitoring for stable operation.