As per the sales agreement, the company has sold the oil refinery, a terminal in Elmendorf, Texas and a pipeline connecting the terminal and refinery.

The oil refinery situated on the South Side of San Antonio is a 14,500 barrel per day facility that processes crude oil and produces liquefied petroleum gas, ultra-low sulfur diesel, jet fuels, naphtha, reformates, specialty solvents and other specialized fuels.

The Elmendorf terminal, which is located about 19.3km from the refinery, stores the crude oil to be processed at the refinery.

NuStar sold the refinery as a part of its business strategy to focus and improve its fee-based pipeline and storage operations, which is more lucrative.

NuStar Energy president and CEO Curt Anastasio said, "The purchase of the refinery was an excellent opportunity for NuStar, but with our strategic direction to focus on and grow our pipeline and storage operations, it was the right time to sell it, and we are pleased that we found the right buyer in Calumet because they are a solid operator and they will continue the momentum we started by investing in the refinery and its employees."

The company said it will continue to assist Calumet in operational and administrative work.