US crude prices fell 4.3 per cent to $31.72 a barrel, while benchmark Brent dropped 5 per cent to $31.83 a barrel amid fears over slowing demand in China and a growing inventory glut.
Santos shares were 3 per cent lower at $3.11, Woodside Petroleum dropped 0.8 per cent to $27.41 and Origin Energy lost 1.5 per cent to $4.18 at 11am (AEDT).
BHP Billiton, which has significant oil and gas interests, was 0.8 per cent lower at $15.43.
Meanwhile shares in Beach Energy were 2.9 per cent lower at $41.75 after it appointed Oil Search executive Matthew Kay as its new chief executive officer to take over from acting CEO Neil Gibbins.
It comes after Origin Energy confirmed its $24.7 billion APLNG project shipped its first LNG cargo to Asia on Saturday.
– with AAP
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