Sempra Energy has signed joint venture and 20-year supply agreements with three companies to support the financing and construction of a liquefied natural gas export facility at its Cameron LNG terminal in southwest Louisiana, the company said Thursday.

The joint venture agreement calls for affiliates of GDF Suez SA; Mitsubishi Corp., through a related company established with Nippon Yusen Kabushiki Kaisha; and Mitsui & Co. Ltd. each to acquire 16.6 percent equity in Sempra’s existing facilities and the liquefaction export project in Hackberry. A Sempra Energy affiliate will retain 50.2 percent.

The supply and joint venture agreements are subject to a final investment decision to proceed by each party, finalization of permit authorizations and securing financing commitments that are expected to occur by early 2014, the company said. The three-unit liquefaction facility will have an export capacity of 12 million tons per year. The supply agreement with each company is for 4 Mtpa.

“These agreements represent a major step forward in the development of our LNG export project at the site of the Cameron LNG facility,” said Mark A. Snell, president of Sempra Energy.

The total cost of the facility, including the cost of the existing facilities plus interest during construction, financing costs and required reserves, is estimated at $9 billion to $10 billion. Construction is expected to start in 2014 with the first phase of liquefaction operations to start operations in the second half of 2017. Two more units are expected to be in operations in 2018.