Maintaining the Lift Gas Compressor peak efficiency; an evaluation of the Lift Gas Compressor performance degradation and the impact to the oil production

Abstract

The BLD field is an offshore oil field located in the northern part of Indonesia that has been producing for more than 25 years. Post its golden era in mid-90 where the oil production peaked at 120 MBOPD, currently BLD field is producing at 7 MBOPD with 25 wells on-line.

Various subsurface and surface optimization effort have been accomplished to maintain BLD field base production. With gas lift as the sole artificial method applied on site for those oil wells, the Lift Gas Compressor (LGC) plays a significant role to the BLD field oil production. The LGC identified as a single point of failure and the LGC performance is closely monitored and should properly maintained at the optimum condition.

The LGC performance evaluated at comparing the baseline (as installed package) condition to the routinely kept records (trends) of the normal operating condition of the engine. Parameters affecting the LGC performance are: inlet air temperature, air quality, pressure losses and outlet temperature. The lower performance corresponds to the lower LGC (gas lift) discharge pressure distributed to the wells, this is directly translates to a lower gas lift pressure available to lift the liquid from the oil wells to the surface.

To maintain the LGC performance at the peak efficiency, close monitoring of the pertinent parameters are highly required to predict a performance degradation and schedule an intervention as required. The most common factor to the LGC performance degradation is contamination that enters the turbine engine. This contamination is considered as a recoverable performance degradation that can be recovered with an engine cleaning.

This paper evaluated the LGC performance degradation and the impact to the BLD field oil production. With such known impact, a proper plan is scheduled to intervene and bring the LGC performance back to the peak efficiency.