ATYRAU, Kazakhstan—Kazakh workers were recuperating from the frigid temperatures of the Caspian Sea over cups of tea when their Italian supervisor interrupted their break, demanding they return to work.

The workers restrained the supervisor—a manager working for Eni SpA, a company building a giant oil development here—and put a plastic bag over his head. He fled, packed his bags and left Kazakhstan.

The spat was a brief episode yet emblematic of the endless challenges that have hobbled a project once hailed as the dawn of a new era in cooperation between oil-rich countries and Western companies.

(Interactive graphic: How four energy giants, 10 man-made islands and nearly $50 billion add up to zero barrels of current oil production.)

Asked about the 2011 incident, which was described by Western oil-company managers, a senior Eni executive said that he wasn't familiar with it but that friction between workers and management is a periodic occurrence.