Conrad Petroleum Ltd., Singapore, confirmed lateral extent of high-quality, Plio-Pleistocene intra-Muda sandstone reservoir in Mako gas field offshore Indonesia with the Tambak-2 appraisal well (OGJ Online, Mar. 11, 2019).
Logs indicated a 33-ft gross, 30-ft net, pay zone with permeabilities calculated at more than 1 Darcy. The reservoir top is 10 ft updip of the Mako South-1 discovery well more than 13.5 km away in the Duyung production-sharing contract area of the Natuna Sea.
Pressures and gas-water contact were the same as those encountered in Mako South-1, Conrad said. West Natuna Exploration Ltd., 90% owned by privately held Conrad, drilled the discovery well.
During preparations for a drillstem test of Tambak-2, a packer failed. While the crew attempted recovery, the well flowed gas to surface and had to be shut in and killed with heavy mud, some of which entered the reservoir.
Two subsequent DSTs failed because of formation damage.
Despite the DST failures, Conrad Chief Executive Officer Miltos Xynogalas called the Tambak-2 results “extremely encouraging” for field development.
“The well confirmed the lateral extent of the high-quality reservoir and the presence of a continuous hydrocarbon accumulation,” he said. “Initial petrophysical analysis suggests high gas saturations, while the gas mobility encountered during pressure measurements and the flow of gas while retrieving the packer confirms the ability of the hydrocarbons to flow to the surface.”
The China Oilfield Services Ltd. Asian Endeavor 1 jack up will next drill the Tambak-1 exploration well, testing a large Oligocene Lower Gabus prospect and intersecting intra-Muda sands.
Conrad operates the Duyung PSC, which covers 890 sq km in 60-100 m of water in the Riau Islands province, with a 76.5% participating interest. Other participating interests are held by Coro Energy PLC, 15%, and Empyrean Energy PLC, 8.5%.