EIG Global Energy Partners, a private equity firm that specializes in investments in energy infrastructure, agreed on Monday to pay Origin Energy Ltd $1.59 billion for a minority stake in Australia Pacific LNG Pty Limited, a joint venture with ConocoPhillips and Sinopec.  

The liquefied natural gas (LNG) project is the largest by liquefaction capacity on Australia’s eastern seaboard and a major supplier of LNG to Asia and gas to Australia’s domestic market, the companies said. Located in Gladstone, Queensland, it holds an acreage position spanning the prolific Surat and Bowen basins, providing long-term reserves.

The project operates at globally competitive breakeven costs and is well positioned to meet growing LNG demand in the Asia-Pacific region, EIG said. After the deal...