Talos' block was adjacent to a lease area controlled by Pemex, and a disputed fraction of the resource extended across the boundary. Both firms commissioned separate audits, and both concluded that they controlled the majority of the reservoir. In 2018, Mexican President Andrés Manuel López Obrador took power and pledged to return control of the oil sector to Pemex. Three years later, just after Talos drilled four wells at Zama, Mexico's energy secretariat (SENER) sided with Pemex and stripped Talos of its operatorship. The decision effectively nationalized control of the asset and left Talos with a 17 percent non-operating share of the unitized field. Talos appealed without success, and ultimately it decided to proceed with sanctioning the project in cooperation with Pemex. The deal acknowledges Pemex as the operator, but it also provides for an "Integrated Project Team" representing the interests of all four companies with a stake in the field.