Optimization of Production Scenario in Jambaran Field to achieve Operation Excellent in Cepu Block

Abstract

A huge gas field development will be implemented in Cepu Block with the target is carbonate build-up reservoir in North East Java Basin. The Jambaran reservoir is at present in the saturated phase that contains both oil rim and gas column (gas cap). An ultimate agreement with end user to deliver gas that produced from gas cap has been contracted. Therefore, all aspects of planning and strategy including subsurface, drilling and completion by considering any potential hazards from geological, drilling, and HSSE point of view need to be prepared perfectly.
In terms of reservoir and future well surveillance plans, there are several aspects needed to focus on, such as production scenario. Around 600-800 ft. thickness of prospect zones will be perforated and produced in order to meet the optimum  production per well which is estimated about 45-60 MMSCFD and the well can be optimally interfered in the future, so that in the associated production zone will be installed casing or liner. Hence, the selection strategies that will be applied become very crucial which the cased hole production strategy itself can use slotted liner or cased & perforation.
After conducting some optimization and by considering the time, cost and safety effectiveness, finally the option of cased hole with perforation is chosen. In addition, the casing design that will be manufactured and the ability to interfere the wells, if necessary, can be fulfilled by this choice. On the other hand, with a profound study, there are two options for perforation strategy: wireline perforation and coiled tubing conveyed perforation. The critical aspect in evaluating the two methods is the safety factor of perforating 600-800 ft. zone. The reason is the reservoir contains sour gas with H2S and CO2 level reaching 1% and 35% respectively. If selected perforation method is not suitable, the fatality such as blow out or leak during perforation will be difficult to avoid.