Soco International Plc, an oil explorer in Asia and Africa, said its Te Giac Trang field off Vietnam is pumping 35,000 barrels of oil a day, less than previous guidance. The shares fell the most in a year.
Output at TGT will remain at current levels while tests on wells and floating production, storage and offloading vessels take place, the London-based company said Tuesday in a statement. Soco said in August that TGT may produce more than 50,000 barrels a day by the end of the year.
The stock dropped as much has 12 percent in London, the biggest intraday slump since Oct. 27, 2010. The shares traded down 9.5 percent at 299 pence as of 8:54 a.m. local time, extending their decline this year to 19 percent.
"The company continues to evaluate exploration opportunities in Southeast Asia and Africa," Soco said in the statement. "Although it is not guaranteed that any new projects will be introduced in the near term, the TGT oil development in Vietnam significantly adds to an already strong balance sheet."
The TGT project remains on course to reach plateau production of 55,000 barrels a day in the first quarter of 2012, Soco said. Drilling of the first well in TGT's second phase started last month, and production is scheduled to begin next August. Soco is also drilling wells off the Republic of Congo.