Reuters reports that Royal Dutch Shell and PetroChina jointly bid more than $3 billion for Australia''s Arrow Energy, marking a Chinese firm''s first foray in the country''s burgeoning coal-seam gas sector and sending Arrow''s shares soaring by nearly half. Arrow said that the bid from a company jointly owned by Shell and PetroChina would give shareholders A$4.45 in cash per share, plus a share in a new entity comprising Arrow''s international business. Shell confirmed it was in discussions to acquire Arrow''s domestic business, but declined to say more. PetroChina said the bid was at an early stage and there was no timetable. Coal-seam gas is natural gas trapped in seams of coal. Arrow has reserves of 6,150 petajoules of coal-seam gas, the largest in Australia.