Conrad holds a 76.5% operational interest in the offshore Duyung permit which contains the Mako gas gas field, one of the largest undeveloped gas fields in the West Natuna Basin.
The revision of resources by GaffneyCline Associates followed data analysis from the 2019 drilling campaign.
Mako was discovered in 2017, and Conrad has been working on proving up resources since.
Conrad managing director Miltos Xynogalas said the revision of resources and the approvals from the government was a significant first step towards development.
"It also represents a significant milestone for the Indonesian government's objectives for its people in the exploitation of the nation's natural resources, with the Mako project enhancing Indonesia's stated goal of doubling its gas production by 2030," he said.
Under the development plan, Conrad plans to produce 120 million cubic feet of gas per day.
Mako will be tied into the West Natuna Gas Transportation System which will pipe it to Singapore.
By utilising the pipeline to Singapore, Conrad said the project would be expediated and first sales gas would be reached in 2025.
"The next key milestone in the development of Mako is the finalisation of a gas sales agreement with a buyer in Singapore," Xynogalas said.
"With recoverable gas volumes and daily production now formally approved within the plan of development revision, we anticipate, and look forward to working with the government of Indonesia, in completing gas sales agreement negotiations at the earliest opportunity."
In its initial public offering documents from September, Conrad said it aimed to have a sales agreement locked in by the end of this year. ‘
It is now conducting front-end engineering and design.
A final investment decision is expected mid-next year.