The political upheaval in Yemen has dealt a powerful blow to the country’s oil industry, forcing companies to abandon productive oil patches and evacuate staff as a rebel group consolidates power.

Houston-based Occidental Petroleum Corp., which has been operating in Yemen for nearly three decades, flew its staff out of the country in January, executives and local officials said, after gunmen stormed its compound in the capital, San’a, where Houthi militants have tightened their grip on power.

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