PETROCHINA Co and China Petroleum & Chemical Corp, the nation's largest oil companies, said some gas wells in Sichuan Province remain shut after the country's biggest earthquake in 58 years struck the area.

PetroChina has cut daily gas output from Sichuan by about 14 percent, or 5.6 million cubic meters, as a safety measure, parent China National Petroleum Corp said yesterday.

China Petroleum, or Sinopec, won't reopen its Western Sichuan gas wells "too soon" due to transport disruptions, after-shocks and shutdowns by customers, spokesman Huang Wensheng said yesterday.

China on Tuesday ordered coal mines, chemical plants and oil and gas wells affected by the 7.8-magnitude quake to halt operations to avoid further casualties. Monday's temblor has killed more than 14,000 people in Sichuan, which holds about 40 percent of China's natural gas reserves.

"The demand for natural gas demand could decline as the province consumes about 19 percent of China's entire natural gas demand," Cheng Khoo, a Hong Kong-based Lehman Brothers Holdings Inc analyst, said in a note on Tuesday. "At this point, the impact from the quake to the companies seems minimal."

China National has shut its refinery in the Sichuan city of Nanchong, it said in its company newsletter China Oil News yesterday. The plant can process one million tons of crude a year, Deputy Board Secretary Jiang Lixin said by phone with Bloomberg News from Beijing.

The state-owned firm's oil and gas fields, refinery and sales units in the area were "affected to a differing extent," China National said.

PetroChina fell 0.6 percent to HK$10.90 (US$1.40) in Hong Kong. Sinopec dropped 2.2 percent to HK$7.49.

Sinopec's Dianqiangui oilfield was closed after the earthquake, spokesman Huang said yesterday.