INDONESIA - Irian Jaya.

The main plays in this frontier province discovered so far are in West Irian. They include the Tertiary pinnacle reef play located on the western Vogelkop peninsula, and the offshore Roabiba discovery made by Occidental Petroleum (Oxy). West Irian has been a significant oil producer in the past.

In 1995 a giant gas field, Wiriagar Deep, was found by Atlantic Richfield (Arco - now part of BP). The gas lies in a Pre-Tertiary formation. Now BP says the field contains more than 18 TCF of gas, of which a large portion will be recoverable, and is hoping to find additional gas reserves in the region. The field lies in the west of Irian Jaya.

In 1994, KUFPEC of Kuwait made a major oil discovery in a Pre-Tertiary formation on the island of Ceram, in the west of Irian Jaya. The company's wildcat resulted in a 6,800 b/d flow of oil, which was the highest of any oil exploration rate in Indonesia during the previous two years.

In March 1996, Santa Fe Salawati announced the discovery of gas in its Irian Jaya block of Salawati. Its SW0-1 wildcat tested 12.5 MCF/d of gas and over 3,500 b/d of oil. But the oil reservoir is said to be small.

Exploration is in its infancy in the difficult mountainous region in the east of Irian Jaya. So far there has been no evidence that the Mesozoic oil play of the adjacent Papua New Guinea extends west into Irian Jaya. However, a deep wildcat drilled beneath a small Tertiary reef field in West Irian was reported in 1994 to have found large quantities of gas in sandstones.

The Natuna Sea, in the South China Sea, is a large shelfal area extending as a northern salient between East and West Malaysia. It contains a number of islands. The western Natuna Sea has a small number of oil and gas fields in Tertiary clastics which are part of the south-easterly extension of the Malay Basin.

The eastern Natuna Sea contains a Tertiary limestone play with reefal limestones built up on a carbonate shelf sealed by shales. One of the world's largest gas fields was discovered there in 1973 by Agip. This is to be developed by ExxonMobil, in the most expensive gas project in the world. Moveable gas in this field, called L, is estimated at 210 TCF. But 71% of this is unwanted CO2, a greenhouse gas associated with global warming. ExxonMobil will be developing the field for a giant LNG project, with the CO2 to be reinjected into the same carbonate reservoir but beyond the limits of the producing structure.