By Greg Morsbach
BBC News, Venezuela
Officials from Argentina, Brazil and Venezuela are meeting in Caracas to lay the foundations for a jointly-financed gas pipeline.
The plans were discussed in January at a presidential summit
The 8,000km (5,000 miles) pipeline would provide Venezuelan gas to much of South America.
It will cut across the Amazon rainforest and run all the way to the southern tip of the continent, and its price tag is $20bn.
Further details are expected to be announced later on Thursday.
The difficulty of the proposed construction is reflected in the size of the government delegations involved in the meeting in Caracas.
Some 20 engineers and economists representing Argentina, Brazil and Venezuela have spent the past day discussing the route of the pipeline, its cost and environmental impact on the Amazon rainforest.
Now their bosses - Argentina's minister for planning and the energy ministers of Brazil and Venezuela - are expected to unveil some of those technical details after almost two days of discussions.
Venezuela's Energy Minister, Rafael Ramirez, told the BBC the project would contribute towards political and economic unity in South America.
"We've already taken the political decision to build this pipeline. Now we're discussing the technicalities," Mr Ramirez said.
So far it is not clear how the construction costs will be distributed among the contributing governments.
Argentina and Brazil are quietly confident that Venezuela with its oil riches may end up paying more than half of the costs.
If they fail to reach consensus on this occasion, the issue is likely to be taken up again by the Presidents of Venezuela, Argentina and Brazil, at their trilateral summit in just over a week's time.