The brown field, Mutiara, has been producing for more than 25 years where its reservoirs consist of thousands of lenses as a result of the deltaic sedimentation. Operated by VICO Indonesia, aggressive drilling program was implemented to arrest production decline and to increase additional oil reserves from existing and newly discovered reservoirs. Current practice of producing natural flow will not be sufficient to recover oil from small lenses reservoir. Therefore, integrated works need to be implemented for the oil development in this field. Splitting focus from gas to oil production is long journey to walk. Major facility upgrading was needed to eliminate gas lift system "blank spot". Additional compressor was also needed to maintain gas lift pressure distribution in southern remote area. A thorough project planning and procedure are established to ensure optimum field production. Oil zones evaluations followed by prioritization are discussed with well intervention and construction team. After perforation is completed, PCTGL was designed with thorough calculation. It is important to accurately measure pressure drop along gas lift line since PCTGL use single unloader valve which is sensitive to injection pressure changes. VICO Indonesia cross function team, consisting of Resource Management, Technical Support and Operation, conducted regular bi-weekly monitor during this development phase. It was important to ensure every team carried out their respective responsibility. Then harvest time is coming; Mutiara oil production delivered average production of 4,981 BOPD in 2016, an increase of average 2,970 BOPD than 2013. The integrated gas lift also managed base production annual decline by delivering above 4,500 BOPD for in 2015. In the last four years, VICO Indonesia also managed to produce cumulative of 5.1 MMBO oil from this project.

Completion type in Vico Indonesia is designed mainly based on the subsurface considerations. Multi-layer reservoir consisting of gas and oil reservoirs related with fluvio-deltaic depositional environment influences the production strategy which will need zone isolation for single or commingled production. Many completion types have been implemented since early development including single or dual selective, monobore, and dual monobore cemented as the most recent completion. There are more than 500 wells drilled and completed using dual monobore cemented completion. This completion type gives constraints on the application of common downhole pump lift. Evolution in the completion type requires a different approach in gas lift technique for oil development. Many gas lift techniques have been applied to address the completion types. The gas lift techniques include the implementation of conventional gas lift with SPM, poor boy, coiled tubing gas lift, and coiled tubing gas lift with unloader. The first two methods are common for selective completions while the last two are fit for purpose for monobore completions. The appropriate modification and selection on the gas lift techniques exhibits a real benefit to optimize oil recovery in these various and evolving completion types in VICO. The contribution is around 70% from total oil production while single year gas lift project contributes to approximately 30% of annual production in respective year. Total cumulative production from the application of these techniques is around 10 MMBO. Modification in gas lift techniques is needed to tackle evolution of completion types. Coiled tubing gas lift with unloader is the newest technique used to enhance the advantage of coiled tubing gas lift application. The modification of gas lift techniques will be described in this paper.

Coiled tubing gas lift (CTGL) implementation in cemented monobore completion which uses 3.5 inch tubing has been a breakthrough in VICO Indonesia. This gas lift technique has been successful on arresting decline and even ramping up the oil production in this brown field. CTGL application in VICO uses only orifice as the injection point without any presence of unloader. Thus, it has limitation on the deepest point of injection given the available pressure at surface. Declining in reservoir pressure as an effect of depletion drive reservoir is the main issue which results in early gas blowing around and shorter production life. Coiled tubing gas lift with unloader has been introduced recently to address the weakness of CTGL by adding unloader(s) to CTGL. The idea is to increase oil production and cumulative production with longer production life. Slight modification is needed on the bottomhole assembly of the CTGL to incorporate the application of the unloader. Designing opening and closing pressure of the valve is very important at this stage. This also includes the design of dome and test rack opening pressure. The trial of this technology has been installed in Nilam well on 2015 and successfully produced 229 BOPD initially which then increase to 807 BOPD with optimization on the injection pressure. Current cumulative production since the implementation of this technology is 152 MBO. This trial project uses 3 unloaders and one orifice as the injection point. The current issue in this project is on the fluctuation of the injection pressure which affects the production rate. Coiled tubing gas lift with unloader is the newest technique used in Vico to address the limitation of cemented monobore completion.

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