BHP Billiton Ltd. (NYSE: BHP), fresh from signing a joint venture to develop an oil field off Mexico, remains on the lookout for more oil assets, as it is more bullish on oil than gas over the next few years, its petroleum chief said March 8.

The global miner, which also has a large petroleum business, has long flagged that copper and oil are its two main targets for growth over the next few years, as it sees potential supply shortfalls emerging for those commodities.

BHP agrees with the International Energy Agency's outlook, released this week, which warned that world oil demand may outstrip supply after 2020 following a sharp decline in investment in new production.

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"We expect and we're seeing that oil markets in 2017 are really already coming back into balance for the first time in nearly three years," said Steve Pastor, president of operations, petroleum for BHP Billiton, told reporters on a conference call after speaking at the CERAWeek by IHS Markit energy conference in Houston.

"And as we look ahead to the 2020s we see compelling market fundamentals," he said. That is based on a view that demand will grow around 1% a year while production will decline between 3% and 4% a year as fields are depleted.

BHP is focused on the $9 billion Mad Dog phase 2 oil development in the deepwater Gulf of Mexico, drilling the Trion prospect with state-owned Petroleos Mexicanos in their side of the Gulf, and exploring off Trinidad and Tobago, while looking for more high-quality oil assets, he said.

"We always are open to and looking at acquisition opportunities," Pastor said.

"Quite frankly, we're a bit more bullish on oil based on the fundamentals that I described, and we would like to add oil proportionately into the portfolio."

He all but ruled out acquiring any assets in Southeast Asia, where companies like Chevron Corp. (NYSE: CVX) are looking to sell or give up assets in Indonesia and Thailand and Malaysia's Petronas is aiming to sell a large stake in a gas block off Sarawak state.

"Quite frankly, in Southeast Asia, where we've played in the past, the prospects, the potential we see there is not a great strategic fit for us at this time," Pastor said.