How One Clause Sparked Exxon-Chevron Feud That Turned Personal

The 20-month feud between the Western Hemisphere’s two most powerful oil companies over the biggest offshore discovery in a generation hinged on a single clause of a contract few people have ever seen.

The passage in a confidential agreement signed more than a decade ago that governs how producers work together in Guyana’s booming oil field was the basis for Exxon Mobil Corp.’s arbitration case that threatened to undo Chevron Corp.’s $53 billion takeover of Hess Corp.

The ensuing dispute upended Chevron’s and Hess’s strategies for nearly two years and threatened to mar the legacies of both ...