Spain’s Repsol has started drilling the much-anticipated Rencong-1X wildcat in the frontier deepwaters of Indonesia’s North Sumatra basin in the Andaman III Block.
According to Aceh upstream authority BPMA in its release last week, the drilling started on 18 July, which is being carried out by the Capella drillship, and will take 66 days to complete at the water depth of 1,100 meters.
Significantly, the block is adjacent to Andaman II block, where operator Harbour Energy discovered gas and liquids earlier this month using the same drillship at its play opening Timpan-1 exploration well.
The region, which is largely undrilled, offers the potential for big gas discoveries. Indeed, if successful, the wildcat could help unlock the deeper areas of basin, which sits on the northern part of Sumatra island stretching from onshore Indonesia to the deeper sections of the Andaman Sea.
The wildcat was due to be drilled in 2019 but was delayed due to a farm-in process that saw Petronas take a 51% stake in the block. A plan to drill in 2020 was derailed by the COVID pandemic.
Crucially, only a few wells have been drilled in the deeper areas of the basin, but none of them confirmed a commercial discovery. The nearest wells to Rencong-1X are Emerald-1, drilled by Eni in 2008, and Bundong Jeumpa-1, drilled by Lasmo in 2000. Neither well gave any encouragement as to the presence of good reservoirs or hydrocarbons, beyond relatively normal minor amounts of gas in thin sands. But Harbour’s recent initial success at Timpan-1 has revived interest in the area.
The entire Andaman Sea area from Aceh to the Gulf of Martaban (Myanmar), which includes the North Sumatra basin in the south, has no known oil generating source rocks. Only gas accumulations, such as Arun and Yetagun, are known. Therefore, a deep-water gas accumulation is possible, but the presence of good reservoir is a major risk.