(WSJ) Private equity firm First Reserve Corp. signed an agreement with Mexican state oil company Petróleos Mexicanos to jointly invest $1 billion in energy projects, taking advantage of the recent opening of the country’s energy industry, the companies said Tuesday.

The projects include First Reserve’s recent investment, along with BlackRock Inc., for a 45% stake in Pemex’s Los Ramones II natural gas pipeline project.

“Pemex and First Reserve plan to invest capital in energy infrastructure projects throughout Mexico, combining the financing, structuring and industrial and operational experience needed to bring these critical projects to fruition,” First Reserve said. “Through formal collaboration with Pemex, we feel we have gained substantial access to a region with strong supportive macro dynamics alongside a motivated and accomplished partner.”

U.S. -based First Reserve, which invests exclusively in energy, also owns a wind-power project in the southern Mexican state of Oaxaca.

Pemex said the agreement will give the state company access to financing and the exchange of technical and operational experience. Areas for investment include infrastructure, maritime transport, power cogeneration, Pemex said.

The ability to invest jointly with private-sector partners comes at a crucial time for Pemex, which faces competition in oil and gas production for the first time in its 77-year history under recent changes in Mexico’s energy laws, and has seen its budget cut this year by around $4 billion with the drop in world oil prices.