In a filing to the London Stock Exchange, Shell said it was to sell 71.6 million shares in Woodside at A$31.10 per share (£18.20) which would value the equity stake at £1.303bn, or US$1.7bn.
The oil major said that represented 64 percent of its interest in Woodside and 8.5 percent of the issued capital in Woodside. The announcement came after Perth-based company's stock closed at $32.24.
When the sale is completed, SEHAL will own a 4.8 per cent interest in Woodside.
Investors in Woodside Petroleum will have to contend with the confirmation last night that Shell is about to sell most of its holding, with the rest not to far behind. The company has agreed that it will not dispose of any of its remaining shares in Woodside for a minimum of 90 days from completion of the sell-down, with limited customary exceptions.
In November 2010, it sold 10 percent of the issued capital of Woodside, taking its stake to 24.27 percent.
After being diluted further because of a decision not to participate in Woodside's dividend reinvestment programme, and what Shell said was a "change in Shell's level of involvement over Woodside's financial and operating policy decisions", management concluded a year ago that Shell "no longer [had] significant influence".
"Proceeds from the sale will contribute to reducing our net debt", Shell Chief Financial Officer Jessica Uhl said in the initial statement.