Publications

Bekasap Formation is the main reservoir in Kotabatak with current recovery factor is 26%. About 31% of total recoverable oil reserve is located in relatively low permeability reservoir (less than 400 mD), which is not effectively drained by current perforation technology and method which is using conventional perforating gun (theoretical deep penetration is less than 29) and overbalance method. Producing oil from the relatively low permeability Bekasap sand has proved challenging in the past. Utilizing regular penetrating guns with overbalance have historically resulted in less than 200 BFPD of production. Productivity Index has been improved via fracturing, but this increases completion costs and the thin shale barriers do not always stop fracture propagation into wet sands. An opportunity exists to improve the effectiveness of completion efforts while developing this field. Perforating simulation software (SPAN*) indicates potential performance for various perforating systems under reservoir and completion conditions. This modeling allows for application of the most beneficial gun system. Extra-deep Penetrating Shaped Charge (59.2 penetration, API-RP19B) has been chosen to maximize penetration depth. Static underbalanced was applied when perforating in an effort to allow perforation tunnels to clean up. WEM Simulator was used to design the underbalanced pressure needed to perforate the wells. This is ascombination of perforation technology and method for first step in improving perforation process.Five wells had been completed using the methodology. 3 wells out of 5 wells are producing on single sand, the others are producing commingle withother sands due to high water cut. The first well completed using this methodology, produced overfive times more fluid than previous wells perforatedwith conventional perforating charges under overbalanced conditions. Additional wells perforated with this technique have had similar, higher than expected, results. The productivity index of relatively low permeability Bekasap Formation has been improved by implementing extra deep penetration gun and static underbalanced perforation technique.