Exports from a major oil terminal in Nigeria operated by a unit of Royal Dutch Shell PLC (RDSA) remain shut-in nearly two weeks after the discovery of a leak in the export pipeline, a spokesman for the company said Monday. Company employees at the Shell Petroleum Development Co have observed a small sheen around the export line to the Forcados oil terminal in the Western Niger Delta during helicopter flyovers. But a spokesman for Shell said less than 15 barrels of oil had spilled since the leak was first spotted March 4. Nigeria is Africa’s largest oil producer, but leaks from the country’s large network of pipelines–often blamed on oil theft–frequently disrupt its oil exports. Last month, SPDC said it shut its 150,000 barrel-a-day Nembe Creek trunkline because of an oil-theft related leak. Write to Sarah Kent at sarah.kent@wsj.com