ExxonMobil hopes to repair faulty Guyana FPSO parts before mid-2021

Oil major ExxonMobil is still working to resolve ongoing technical challenges and design issues on its Liza Destiny FPSO, operating offshore Guyana, as it awaits the arrival of a key component that will allow the continuation of normal operations.

The  SBM Offshore-owned FPSO Liza Destiny has been producing oil for ExxonMobil from the Liza field since December 2019, less than five years after the first discovery of hydrocarbons.

ExxonMobil’s troubles with the FPSO started in January 2021 following technical issues with a gas compressor, which forced the company to temporarily increase the flare above pilot levels in order to maintain safe operations.

Since then, ExxonMobil has been working with the vessel’s owner, SBM Offshore, and the equipment manufacturer, MAN Energy Solutions, to fix the issue with the start-up now planned to occur before mid-2021.

To remind, after completing necessary repairs, upgrades, and mechanical testing at the MAN Energy Solutions workshop, key components of the gas compressor left Germany and arrived in Guyana earlier in March, after which the offshore team started working on the reinstallation and repairs.

By the end of March, teams of experts were making final preparations for the start-up of the flash gas compressor on the Liza Destiny FPSO in order to restore the flare to background levels. However, the issue was not resolved within the expected timeline. 

Namely, following the safe reinstatement of the repaired and upgraded components of the flash gas compression system in early April, the team onboard the Liza Destiny FPSO initiated a comprehensive three-phase testing programme. 

After the completion of the first two phases, the third and final phase was supposed to take place after the removal of temporary instrumentation. The third phase involves monitoring the performance of the machine closely in normal, steady-state operation.

But, as the company was conducting the final phase of testing, it encountered an additional problem with the discharge silencer, forcing it to reduce production to a minimum level and minimise the flare. 

ExxonMobil voiced its disappointment with the FPSO design issue and said that its performance was below the company’s global expectations for reliability. 

The discharge silencer was removed later in April for further assessment of the damage and to determine the necessary scope of repairs and/or modifications. It was estimated that repairs or replacement would take about three months.

Additionally, ExxonMobil said in an update on 21 April that plans initiated in 2020 were progressing to install a redesigned third stage flash gas compression system at the end of this year.

Also in April, the company started to slowly ramp up production to between 100,000-110,000 barrels per day at a flare level of no more than 15 Mscfd. It is important to note here that the FPSO was designed to produce up to 120,000 barrels of oil per day, with a storage capacity of up to 1.6 million barrels.

In its latest update, published on 15 May, ExxonMobil said repairs and upgrades to the third stage discharge silencer, a key component of the flash gas compression system for the Liza Destiny, are being progressed by MAN Energy Solutions at a facility in Houston. The company added that the manufacture of a redesigned third stage discharge venturi has been completed and it is being shipped to Guyana.  

Currently, the plan is for the equipment to be back in Guyana and reassembled for safe start-up in June 2021. 

While repairs are ongoing, production at the Liza Destiny continues at the same level as revealed in April with a flare level below 15 Mscfd.

“ExxonMobil Guyana remains fully committed to resolving these technical challenges as quickly as possible and remains engaged with relevant government agencies to ensure operations are executed safely taking environmental, technical and economic factors into consideration”, the company concluded.