The Success Story of Optimization Gas Turbine Compressor and Generator Fuel Gas Pressure to Maximize Production in X Field

Abstract

X plant with capacity 800 MMscfd has 2 major process plant, Inlet Compression system to lower the inlet pressure and gas plant to treat the raw gas to meet sales gas specification. The inlet compression consists of inlet cooling/separation and compression system. Currently, the inlet compression was operated with pressure 455, 420 and 400 psig at inlet header, separator, and suction compressor respectively. The condensate from separator flow to condensate stabilization system with pressure 380 psig. The flash gas in condensate system then used as fuel gas for gas turbine engine at 340 psig. There was a well drilling plan which require to shut-in one major well and lead to X production decrease to 670 MMscfd with inlet header pressure 455 psig. Reducing inlet header pressure couldn’t be done due to separator pressure requirement whereas allowing condensate can still flow to condensate system then become such a process bottleneck. Deep evaluation was performed to lower the fuel gas supply pressure of Turbines in purpose lower pressure in condensate system in term of gas hydrocarbon dewpoint, LHV, wobbe index, fuel gas valve opening, engine performance, acceleration time from light-off to idle speed, drop on speed/frequency during transient to maximum possible load. As study concluded, performance test was conducted and succeed to decrease the fuel gas supply pressure from 340 to 260 psig, then it is beneficial to reduce the inlet header pressure from 455 psig to as low as 375 psig. The optimization of HP fuel gas pressure can maximize production in X field from 670 MMscfd to 720 MMscfd with no additional capital cost during shut-in major well for new well drilling. Therefore, optimizing the fuel gas pressure of Gas turbine engine can maximize the well production.