Chevron seeks to exit Caltex Australia with $3.6 bln stake sale

* Chevron (Swiss: CVX.SW - news) selling 135 mln shares at 9.7 pct discount to Fri close

* Caltex up 10.7 percent this year, outpacing benchmark Aussie index

* Asia's No. 2 block deal this year (Adds background, deal milestone)

By Denny Thomas and Byron Kaye

HONG KONG/SYDNEY, March 27 (Reuters) - U.S. energy firm Chevron is seeking to sell its entire stake in Caltex Australia Ltd for about A$4.6 billion ($3.6 billion), exiting Australia's biggest refiner after nearly 40 years as falling oil prices and high costs hurt margins.

A successful sale of Chevron's 50 percent stake, which the company is offering at a discount to market prices, would make the deal Asia's largest block transaction after the government of India raised $3.6 billion by selling a stake in Coal India (BSE: COALINDIA.BO - news) Ltd in January.

Chevron is offering 135 million shares in Caltex at a floor price of A$34.20 each, a 9.7 percent discount to Friday's close, according to a term sheet of the deal seen by Reuters. Caltex shares have risen 10.7 percent this year, outpacing a 9.4 percent rise in the benchmark Australian share index.

A halving in global oil prices since mid-2014 has added to the pressures on Australian refiners, which are grappling with ageing equipment, cheaper imports and high costs. Many firms, including Caltex Australia (Stuttgart: CLZ.SG - news) , have closed refiners while others have restructured operations.

Chevron is the latest global major to exit Australia's refining industry. Last year, Royal Dutch Shell Plc (Xetra: R6C1.DE - news) sold its Australian petrol station and refinery operations for A$2.9 billion and BP Plc, which shut down its Bulwer Island oil refinery in Queensland, is also selling its Australian bitumen business.

In a statement, a Caltex spokesman said that Chevron had made clear its sale was part of a broader portfolio review.

"There will be no change to our ability to reliably and competitively deliver all our customers' fuel requirements," the spokesman added.

Australia has experienced a rush of block trades in the past month as investors look to capitalize on frothy valuations following a share market that is rising on hopes of more rate cuts.

Goldman Sachs (NYSE: GS-PB - news) is the sole underwriter for the deal, the terms showed.

($1 = 1.2837 Australian dollars) (Reporting by Denny Thomas; Editing by Miral Fahmy)