Publications

Peciko is a giant gas field located in offshore Mahakam delta, Indonesia. Hydrocarbons are accumulated in multi-layer reservoirs corresponding to several disconnected stacked distal mouth bars. The trap consists of a 4-way dip closure. The field is producing since 1999 and the reservoirs are depleted with strong variation from one layer to another. Building dynamic reservoir models from a mature field with around 90 layers in production and roughly 300 Geological Pressure Unit, is very complex and time consuming. However, locating and quantifying depletion are keys to identify partly drained areas and launch additional developments. It is observed that pressure depletion is function of net sand stacking, stratigraphical units and gas production which is related to the well spacing. Depletion is modeled using pressure measured at wells and actualized to certain time then distributed for each layer in the static model using net pay as geological constraint. By predicting current pressure, present hydrocarbon-in-place can be estimated and mapped. Gas material balance (P/z vs. gas production) was used to quantify future production from existing wells, layer by layer. The result was then integrated in the static model and it helped identifying the un-drained areas, thus incremental resources for the future wells. The final result of this approach is a remaining hydrocarbon-in-place stacked map which is used to define new development wells and their associated resources. The automatic workflow involved an integration of many data and analysis from more than 100 wells that can be up-dated easily in reasonable time.