Abstract

Historically, Indonesia's petroleum economy has been based on Tertiary oils and reservoirs, largely in the major deltas of the Indonesian archipelago and in Tertiary carbonates. Production is characterised by relatively low well productivities (<1,500BOPD) and complex interbedded reservoirs (e.g., Bishop, 1999c; Collins et al., 1996; Snedden et al., 1996). Australian petroleum geology is a rather simpler affair with thick major regional reservoirs underlying a thick regional seal (Whittam et al., 1996). In the North West Shelf the reservoir is predominantly Triassic in age, but in the Timor Sea it is Jurassic. Over the last decade, discoveries in Australian waters have moved steadily closer to the Indonesian border.

Laminaria established a Jurassic oil play to the west of the Zone of Co-operation. Sunrise/Troubadour established a gas play to the east. Both plays offer the promise of simple and thick Plover reservoirs with high well productivities (over 11,000 BOPD in some Laminaria wells). However, the first significant Indonesian Mesozoic hydrocarbon discovery was in Irian Jaya. There, a Jurassic source and reservoir similar to, but subtly different from, the Plover, reservoirs a world class gas accumulation – Tangguh.

New drilling results in the Masela PSC, adjacent to Australian waters have finally proved the extension of a classic "Australian" play into Indonesian waters. A large dry gas accumulation represents just one part of a whole family of gas fields in Northern Australian and Indonesian territorial waters. The discovery process for this field involved a complex interaction of geology and geophysics, oil companies and contractors, and government agencies all working together to mature an idea into reality.

Ultimately, economic development of this discovery will require cooperation between companies and nations to build a large gas gathering system. Meanwhile, new acreage offerings around Aru need to be understood in an Australian context.