Sumatra accounts for more than half of Indonesia's oil production, coming from Riau province, in West and Central Sumatra, from Aceh province in the North, which also oversees the administration of Natuna islands, and from South Sumatra.

Java, the most populated island in Indonesia, is by far the biggest oil and gas consumer in this country. Parts of the island and the adjacent Java Sea form an oil and gas province. Numerous oil and gas fields have been located offshore.

East Kalimantan, on the island of Borneo, is the other main petroleum-producing region.

The growth in Indonesian oil production was dramatic over the decade leading up to its first peak in 1977, more than tripling in volume to 1.6 million barrels per day.

After this initial stage, production fell until secondary and tertiary technology, production optimization and the development of new fields reversed the trend and brought production back up to peak volume again in 1995.

Since then, production has declined steadily, due to diminishing yields from the nation’s mature oil fields. Production fell below 1.0 million barrels per day in 2007.

The challenge now is to uncover or exploit untapped reserves within the archipelago, which will require significant investment.