July 17 (Reuters) - CNOOC Ltd
* Nexen Energy says thinks restarting ruptured Long Lake pipeline will take "some time"
* Nexen says operations shut down almost immediately when Long Lake pipeline leak discovered
* Nexen says ruptured pipeline was new and installed last year
* Nexen Energy apologises for 31,500 bbls Long Lake, Alberta, pipeline spill, says "we are deeply concerned about this"
* Nexen says ruptured pipeline was connecting Kinosis oil sands operations to Long Lake facility, Kinosis produces about 9,000 barrels per day
* Nexen says company still trying to find out root cause of pipeline leak, does not know exactly when leak started
* Nexen says visible breach in the double-walled Long Lake pipeline, about the size of a hand Further company coverage: (Reporting by Nia Williams and Mike De Souza; Editing by Jeffrey Hodgson)