Sunoco Inc.'s parent company said Tuesday that the regional fuel retailer would retain a substantial corporate presence in the Philadelphia area after it merges this year with a Texas convenience-store chain.

Energy Transfer Partners L.P., the Dallas pipeline operator that bought Sunoco two years ago, announced Monday that it is buying Susser Holdings Corp. for $1.8 billion.

Susser operates 630 company-owned convenience stores in the Southwest, mostly under the Stripes brand, and is a wholesale distributor of motor fuels to 616 other dealers and 1,800 commercial customers. Sunoco's 5,000 retail outlets are mostly on the East Coast.

Where various corporate functions will be based after the merger is still being sorted out, said Vicki Anderson Granado, an ETP spokeswoman.

The combined retail operations will be headed by Sunoco chief executive officer Robert W. Owens, who is based in the Philadelphia area. But the assets will be owned by Susser Petroleum Partners L.P., which will retain its headquarters in Houston.

"Our integration work on the Susser acquisition has just begun and is focused on creating a combined enterprise that will leverage the individual strengths of these entities, while preserving the earnings power of our existing businesses," Granado said in a statement. She framed the Susser acquisition as an add-on to Sunoco.

"Since it acquired Sunoco in October 2012, Energy Transfer has consistently supported growth in the Sunoco business, with acquisitions in Virginia, Maryland, Tennessee, and now Texas," she said. "The addition of Susser to Sunoco's network gives us a powerful platform for future growth."

Sunoco previously announced plans to move its headquarters to Newtown Square in early 2016.