PHILADELPHIA (AP) — The oldest and largest refinery on the East Coast will stay open thanks to a deal between Sunoco and the private equity firm The Carlyle Group, with the groups announcing Monday that they have agreed to terms on a joint venture at the facility.

The new venture also will make a substantial investment in the facility to help it import lower-cost oil from North Dakota’s Bakken formation, shift to refining a higher proportion of ultra-low-sulfur diesel and use natural gas from the booming Marcellus Shale formation that lies below much of Pennsylvania, Carlyle officials said.