Reservoirs of Zone 12, Zone 15 and Zone 16 of The Upper Cibulakan Formation South Pamanukan Field Northwest Java Basin



The Upper Cibulakan Formation has 190 meter thickness (1706–1516 meter depth). The reservoir is devided into Zone 12, Zone 15 and Zone 16. They consist of siltstone and clastic carbonate intercalated with sandstone. The age is N.7 to N.8 deposited in the Inner Neritic environment. There are some shalebrake between reservoir horizons. The Pamanukan field is dominated by normal fault within inversion. The seismic interpretation reveals both half and grabens within NW-SE axis of anticline direction. Structurally, well Pm-2 with gas production has a higher position than the tested gas well of Pm- 1, but both of them have a similar log lithology. Reservoirs thickness is about 3 to 9mts. The N/G is about 0.6 to 1. Petrophysics values from Pm-1 to Pm-2 are as follows: porosity 20 – 24% and 15 – 20%; water saturation 40 – 60% and 62 – 78 %; and permeability 2.4 – 6.5 mD and 3.6 – 8.7 mD. The gas water contacts (GWC) as follow, Zone 12: -1580mt, Zone 15: -1681.8mt, and Zone 16: -1707mt. The recovery factor and remaining reserves from upper to lower zone are as follows: Zone 12: 15% with RR: 3839Mmscf, 14.85% with RR: 12731Mmscf and 6.61% with RR: 20530MMscf.


Authors : Premonowati, Sudarmoyo, Agus W, Joko P, Budi E, Arief N, Eka P