Oil major Royal Dutch Shell is to raise around $5bn after tax through the sale of a hefty chunk of its stake in Australian energy group Woodside Petroleum.The Anglo-Dutch group said it would sell a total of 156.5m shares, equal to a 19% stake, to take its holding in the company from 23.1% to 4.5%.It has long signalled that it would reduce its exposure further to Woodside, after selling a 10% stake in November 2010.Shell's Chief Executive Officer Ben van Beurden said that the disposal is "part of our drive to improve Shell's capital efficiency and to focus our Australia growth in directly owned assets".As part of the deal, Shell's subsidiary Shell Energy Holding Australia Limited (SEHAL) will sell 78.27m shares (9.5% stake) at A$41.35 a share to equity market investors.Meanwhile, Woodside will also buy-back 78.27m of its shares from SEHAL at $34.24 per share."[The sale] doesn't change our view of Australia as an important player on the global energy stage, or Shell's central role in the country's energy industry," van Beurden said.Woodside's shares, closed on Monday at a three-year high of A$42.85, were halted in Sydney trading on Tuesday.BC