An employee walks on top of an oil tank at a Sinopec refinery in Wuhan, Hubei province in this April 25, 2012 file photo. China's biggest state-owned oil firms, sitting on ageing fields, are ... more 
An employee walks on top of an oil tank at a Sinopec refinery in Wuhan, Hubei province in this April 25, 2012 file photo. China's biggest state-owned oil firms, sitting on ageing fields, are scrambling to ramp up crude oil and natural gas production to meet surging domestic demand through a slew of investments that also risk pushing up their costs. PetroChina, Sinopec Corp and CNOOC Ltd produced more oil and gas in the first nine months of this year, the companies said in the past week. That was partly in response to the government's recent hike of domestic natural gas prices and moves to link pump prices more closely with international crude costs. The increase, however, is far from enough to bridge the gulf between the energy consumption and production of China, which last month overtook the United States to become the world's largest oil importer. REUTERS/Stringer/Files (CHINA - Tags: ENERGY BUSINESS) CHINA OUT. NO COMMERCIAL OR EDITORIAL SALES IN CHINA less 
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Reuters | Photo By DARLEY SHEN / REUTERS
Wed, Oct 30, 2013 9:32 AM EDT