The company said in a statement that the subsea line was shut when a leak was discovered on March 4, 2014, leading to suspension of SPDC and third party crude oil exports through the terminal.
Helicopter over flights showed a slight sheen around the export line.
A joint investigation conducted by representatives of communities, SPDC, regulators and security agencies determined that the leak was caused by third party interference; unknown persons had installed a crude theft point on the line in water depth of about eight metres.
SPDC has mobilised equipment and materials to the site, and is working to repair and reopen the line as soon as possible.