One source said the deal was worth $500 million, while a second source said it was worth close to $600 million, adding that the deal would be signed early next week.
Pemex and First Reserve both declined to comment.
Bloomberg first reported the deal earlier on Wednesday.
Pemex, which has suffered from a prolonged oil rout, will sell some of its infrastructure assets to First Reserve, but will continue to use them and pay rent.
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