Chevron abandoned Australian shale exploration and said it will sell its 50 percent stake in that nation's largest oil refiner.

San Ramon-based Chevron notified Beach Energy, its partner in the central Australian shale project, that "the opportunity does not align strategically" with the U.S. explorer's portfolio, according to a statement Friday from Beach. Selling its half of refiner Caltex Australia is expected to yield at least $3.6 billion.

Chevron announced plans earlier this month to shed $15 billion in oil and natural gas assets by the end of 2017 and reduce spending on new projects for the next two years. Chairman and Chief Executive Officer John Watson is raising cash and curbing expenditures after the plunge in global oil prices dented profits and made some fields less attractive to drill.

"They are perhaps looking to increase their margins and get away from businesses that offer lower-end margins," said David Lennox, a resource analyst at Fat Prophets in Sydney. "They are getting knocked around a bit," by oil prices.

Chevron entered Australian shale two years ago when it pledged to invest $349 million in Beach's Nappamerri Trough gas project. Beach said Friday that it will seek other partners and continue studies at the site through June 2016. Icon Energy is also a partner in the venture.

Chevron has been trimming its refining portfolio for the past decade to focus on higher-margin investments such as oil drilling. The company sold about $14 billion in refineries, filling stations and related assets between 2004 and the end of last year.

Chevron plans to sell its shares in Caltex Australia at a minimum of A$34.20 apiece, a 9.7 percent discount to Friday's close, according to terms of the deal obtained by Bloomberg. It has received enough orders to sell the shares higher, at a minimum A$34.90 each.

The deal underwritten by Goldman Sachs Group is the largest block trade ever in Australia, exceeding Royal Dutch Shell's sale of Woodside Petroleum shares in 2010 for about A$3.3 billion, according to data compiled by Bloomberg. So-called cornerstone investors agreed to buy about A$2 billion of the Caltex stock before the offering started, the people said, asking not to be identified discussing private information.

Caltex, the biggest Australian-based refiner, has risen 74 percent in Sydney in the past 12 months. It closed Saturday at A$37.88.

Chevron expects to sell the shares in Caltex to a broad range of Australian and global institutional investors, Chevron said Friday in a statement.

In the Asia-Pacific region that includes Australia, Chevron's net cash refining margins were less than $1 a barrel during the last four years, compared with more than $6 at its North American plants.

The moves will have no impact on Chevron's Gorgon and Wheatstone gas-export projects in the country, the company said.