Chinese oil firm PetroChina is looking to raise more than $5.5bn (£2.7bn) to fund foreign expansion by selling shares on the Shanghai stock market.
China's largest oil firm is looking abroad for new reserves
Like other Chinese energy firms, PetroChina is urgently searching for new sources of oil and gas to support China's continued economic growth.
China has tapped oil-rich African nations, as well as Iran and Venezuela.
Money raised will be used to finance overseas acquisitions and to build refineries and pipelines in China.
Thirst for energy
PetroChina, part of the China National Petroleum Corporation, has not set a price for the four billion shares it plans to sell for up to $6bn, but the move was welcomed by analysts.
The firm's Hong Kong-listed shares rose more than 7% in trading, raising the firm's stock market value to more than $273bn.
China's thirst for energy has, up to now, been handicapped by limited domestic reserves.
But PetroChina said last month it had made the largest crude discovery in a decade.
The find, off China's north eastern coast, has proven reserves of almost three billion barrels.