N-5 well is located on XN offshore platform with ESP completion and was produced with very high water cut. The well was completed and perforated in A, B, C and F zones with straddle packer to isolate E zone. One time the water cut was suddenly decreased. The analysis of well completion suspected that there's leaking on Straddle packer covering E zone which the booked recoverable reserves 2 MMSTB was not appraised yet. The previous N-5 production data from Dec-00 to Jan-01 reported that the E zone can't produce continuously due to excessive gas which caused ESP shut down by gas lock problem.

Referring to the DST result of the offset well (N-1 well), found that the E zone have a good oil bearing, and good reservoir properties (Porosity, Permeability, Swi). Evaluation was made to identify any possibility to produce E zone with customized completion design. Combination of gas lift valve, ESP gas separator, VSD and selective completion was made and successfully anticipate gas lock problem on ESP. The gas can be separated from ESP, then release it through gas lift mandrel above the ESP.

In the initial condition after workover job, N-5 well was produced from E zone with very low rate and caused ESP shut down due to low influx. By taking advantage from selective completion we could optimize production through "Switching Method".

Optimization completion design by using combination of gas lift valve, ESP gas separator, VSD, and selective completion resulting continuous production from E zone, reducing 99% water production, increasing oil production of N-5 well, and move reserve status of E zones from 1P to 2P.

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