Publications

In gas field development, well proposals, well completions, and production systems sometimes are not always fixed. Especially in gas fields with a long production history, new stimulated treatments always need to be developed, such as shuting-in producing wells with high water cut, infill drilling new wells, stimulation, hydraulic fracturing, perforating, and others. Gas field development strategy is an economically important problem that has received attention from the petroleum engineering community. The development of Alur Siwah (AS) Field has been planned to drill 3 development wells to optimize sweep efficiency and maintain plateau gas rate. The 3 wells will be drilled three years after submitting the Plan of Development. Several work programs are implemented to increase gas deliverability before the onstream of new wells. One of the work programs is acid fracturing. Generally, it is used to increase the productivity index of the wells produced in tight reservoirs. The AS field reservoir is a carbonate buildup reservoir. The thickness expands from 45 m on the northern edge of the field to 458 m near the southern end. The field has two main reefal facies: Peutu (mainly skeletal limestone) and Tampur (dolostone with fracture and vuggy macro porosity). The Hydraulic fracturing is targeted in the Peutu limestone of AS-9A and AS-11 wells. The permeability is < 1 mD and has high Acid solubility (>85%); from a geological and reservoir engineer viewpoint, the Peutu limestone reservoir in AS Field is an appropriate acid fracturing candidate. The implementation of acid fracturing in AS-9A and AS-11 shows good result, both from the operational and production aspects; the production gain result is up to 90%. The success story of acid fracturing in those wells gives another option for field development strategy. A development study has been conducted to create a better plan for developing this field. Updating the history matching and simulation model with virtual grid connection and local grid refinement in the dynamic model is conducted in this study. To ensure the economic target was achieved, the sensitivity model was also built to compare the number of wells, initial rate, plateau duration, cumulative production, and gas well deliverability. On the other hand, the opportunity map index in the numerical simulation model was also generated to ensure the well location is accurate. The result of this study shows that the number of wells drilled in AS field can be optimized with 2 wells instead of 3. The cumulative production is as good as the previous development plan, and the economic analysis also shows a better NPV. The sequence process to create a better development strategy and an integrated workflow are discussed in this paper, including geological issues, subsurface engineering, operational aspects, and economic analysis.