Under terms of the agreement, the two joint ventures covering Geographe and Thylacine will align to form one new joint venture with Woodside continuing on as operator.
Woodside's Otway Basin development manager Bruce Steenson said the decision means the partners can move towards the selection of a development concept in the second quarter of this year.
"This is a major step forward for the project and will enable the team to work towards a single development proposal for two fields under one joint venture," Mr Steenson said.
The agreement also brings about an end to legal proceedings in the Tasmanian courts between Origin, Benaris and Woodside over inter-party rights and obligations in T/30P.
Post-agreement interests are Woodside Energy (51.55%), Origin Energy Resources (29.5%), Benaris International (12.7%) and CalEnergy Gas (Australia) 6%.
