Sunoco agreed to acquire Offen Petroleum for around $600 million in cash.

The energy company said the addition of Offen, which distributes around 2.5 billion gallons of fuel annually in the U.S., would bolster its existing fuel distribution operations.

The deal is expected to be immediately accretive and boost cash flow for reinvestment and distribution growth, Sunoco said.

The deal is expected to close in the fourth quarter.