The National Petroleum Committee, the screening body in charge of the Erawan and Bongkot gas field auctions, will choose the winners within two weeks as the final bidding envelopes are considered.
In December, the National Energy Policy Council will consider and approve the winners.
There are four envelopes for each proposal: a legal qualification for petroleum E&P operators; an acceptance for the government to hold a 25% stake; technical and investment plans; and the gas price to the state along with a profit-sharing agreement of at least 50%.
These proposals require the participation of state agencies for a joint venture after the winning bidders are announced.
Energy Minister Siri Jirapongphan said the last proposals are the most crucial for auctions, with 65% weighting.
"The participation of state agencies, in particular, requires a joint venture with 25% ownership in each gas field," he said.
The ministry also ordered state agencies to be shareholders on behalf of the government, investing 250 billion baht in each field.
"We are opening each bidder making proposals to state agencies, but the government makes the final call in choosing the agencies," Mr Siri said.
In late September, the Mineral Fuels Department, the auction host, announced that there were only two large companies, Chevron Thailand Holdings Ltd and PTTEP Energy Development Co, vying in the final round for the auctions of the Erawan and Bongkot gas fields.
Both companies are the existing operators: US-based Chevron runs Erawan and PTTEP operates Bongkot.
The ministry said the National Petroleum Committee is the screening committee of the auctions and will finalise possible winners within the next two weeks.
The National Energy Policy Council, chaired by the prime minister, will consider and approve the winners in December after the cabinet acknowledges and approves the list.
Two 10-year contract signings are set for February as the ministry planned earlier, but daily gas production will be trimmed to 1,500 million standard cubic feet per day from 2,150 MMSCFD.
The department estimates that the auctions for the two gas blocks will come with combined capital expenditures and working capital of 1.2 trillion baht over the next 20 years and bring in 800 billion baht in revenue to the state.
Mr Siri said North Bongkot has a natural gas output of 604 MMSCFD and the E&P operator must drill 455 holes, a high ratio when compared with the Yadana gas field in Myanmar that produces 755 MMSCFD from drilling just 21 holes.