According to partner Coro Energy, the results include a significant resource upgrade compared with the previous study, issued in January 2019.
The 2C recoverable resource estimate has risen by 79% to 495 bcf, with 3C resources 108% higher.
Results suggest Mako is one of the largest gas fields ever discovered in the West Natuna basin, Coro said, and possibly the largest confirmed undeveloped resource in the area.
Gas volumes should be upgraded to reserves following execution of a gas sales agreement and a final investment decision to develop the field.
Mako is close to the West Natuna pipeline system: its gas can be marketed to buyers in Indonesia and Singapore, and one Heads-of-Agreement is already in place with a buyer in Singapore.