The well has intersected the two primary reservoirs, TRM3 and K sandstones, at the same or slightly higher levels than at Bunian 3 ST2, the most prolific well in the field.
Both zones have exhibited oil shows comparable to Bunian 3 ST2 with 5 metres of net oil pay in each zone.
Shows in secondary targets
Furthermore, oil and gas shows were recorded while drilling through secondary targets, the TRM 0 and GRM sandstones.
The significance of these will be evaluated further based on the results of the wireline logging and sampling which was successfully run after completion of drilling operations.
This work will quantify the reservoir potential of these zones for future production.
Bass has realigned its corporate strategy following the landmark acquisition of a 55% interest in the Tangai-Sukananti KSO producing assets, which include the Bunian wells.
Joint venture participants in the KSO are Bass Oil, operator with 55%, and Mega Adhyaksa Pratama Sukananti Ltd (MAPS) with 45%.
As at July 2019, the Tangai-Sukananti KSO was producing on average 750 bopd from four wells (JV share).
Bunian-5 well was drilled to TD at 1,662 mKB following which wireline logs were acquired to confirm the nature and quality of oil and gas pay zones within the well.
The rig has run and cemented the 7” production casing and is now preparing to complete the well for production.
Bunian-5 is modelled to come online at 750 barrels of oil per day and produce 546,000 barrels of undeveloped recoverable oil (JV share) at the primary TRM3SS reservoir level.
The well results are consistent with this pre-drill expectation.
Bunian-5 was a vertical well drilled from the surface location of the Bunian-4 deviated well and took 23 days to drill and complete, reaching a total depth of approximately 1,662 metres.
Given this success case, Bunian-5 will be completed and brought into production as soon as possible after the rig has moved off site.
The drilling expenditure will be fully cost recoverable against existing production under the terms of the KSO.
Bunian field overview
Bunian Field was discovered in 1998 with Bunian-1 and Bunian-3ST2 in production.
The entire KSO area is fully defined by the 2011 Sukananti 3D seismic survey data, which was comprehensively reprocessed in 2014 to a very high quality.
Bunian Field is a SW-NE trending anticline bounded by faults to the south, west and east and the elongated structure has two structural crests mapped at the primary objective TRM3SS reservoir level.
Bunian-5 has tested one of these crests and has confirmed the oil potential of the northern half of the Bunian Field.
Three reservoir levels
The Bunian Field contains oil at three reservoir levels and Bunian-5 targeted the primary TRM3SS and secondary GRM and K reservoir levels, which produced or tested oil at Bunian-1, Bunian-3ST2 and Bunian-4 wells.
For the combined reservoirs, the Bunian field has total best-estimate remaining recoverable reserves of 2.09 million barrels of oil JV share with 602,000 barrels oil net entitlement reserves to Bass.
In addition to the existing fields, Bass has defined the exploration prospects of Sukananti Updip and Bunian West.
Both prospects target oil potential at multiple reservoir levels which contain the oil in the existing Bunian and Tangai Fields within the KSO.