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The NSO "A" offshore development was originally designed to deliver 450 MMSCFD wet gas at 800 psig pipeline pressure to feed the onshore gas processing unit. The treated gas is compressed using a centrifugal compressor driven by a Frame 5, twoshaft gas turbine to meet the existing LNG plant processing pressure requirement downstream of the onshore sulfur processing unit. The platform started up in 1999. The onshore sulfur processing plant initially only processed 420 MMSCFD. In order to meet gas demand, the unit was upgraded in 2004 by adding an Oxygen enrichment unit to improve combustion and reduce SO2 emission. This upgrade was expected to increase onshore gas processing capability and NSO "A" platform gas deliverability to 470 MMSCFD. Under typical operation conditions, the original booster compressor was expected to reach its maximum power limit with 450 MMSCFD gas throughput. Based on modeling and simulation, the booster compressor with the gas turbine driver should have adequate capacity to accommodate the higher gas flow rate. An equipment performance evaluation, including mechanical and control aspects, was done to validate the model and ensure that the compressor had the capacity required to process the additional gas. Furthermore, the field evaluation found that electronic setting of the axial compressor's Inlet Guide Vane (IGV) did not match the mechanical movement of the IGV itself. Restoring this setting based upon the performance testing successfully resulted in the increasing the delivery to 470 MMSCFD. This compressor modeling and field testing eliminated the need for gas turbine and compressor overhauls saving approximately US$ 1 million. This paper describes the compressor modeling and simulation, field evaluation, troubleshooting and equipment performance test results.