Production Optimization under Pigging Activity

Abstract

Pigging Activity was carried out in September 2017 on the 20" and 24 Kilometers subsea pipeline which is connected from Platform B (PF-B) to the Onshore Receiving Facility (ORF). The gas production was only supported from Platform A (PF-A) as the PF-B should be shut in for 18 days during the activity. This event impacted to the feed gas to the 2 operating LNG trains to become only one.
The production gas from PF-A in August 2017 was still able to fulfill the processing capacity for 2 Trains, however with reservoir pressure depletion, it was indicated that PF-A production would be insufficient to keep 2 trains running during pigging activity.
To ensure PF-A gas production was able to feed gas to the 2 LNG trains during pigging activity, the effort of slowing down the reservoir pressure from wells in PF-A was then carried out by ramping down the production from PF-A, while at the same time PF -B wells production increased to compensate production as a feed gas to the LNG trains. It sounds like a straightforward approach, but several risks might emerge onto the surface such as; choke erosion, sanding events, and onshore facility setting adjustment. The multi-discipline team work was performed to mitigate risks and apply the possible solutions.
The effort was able to give a positive result in PF-A gas production with a gain of close to 20-30 mmscfd, and 2 LNG trains stayed in operation during the pigging activity. Beyond the result, the potential risks related to choke erosion and sanding events was able to manage on the shelf. All those outcomes were achieved with no additional costs through the rigor action started from planning, implementation, and surveillance by Operations, Process and Petroleum Engineering Team.