The assets sold also include the Red Butte pipeline, a 570-mile pipeline that is the only export line in the area. The effective date of this transaction is Jan. 1, 2016, and closing is expected mid-year 2016. In separate transactions, Marathon Oil has signed agreements for the sale of its 10 percent working interest in the outside-operated Shenandoah discovery in the Gulf of Mexico, operated natural gas assets in the Piceance basin in Colorado, and certain undeveloped acreage in West Texas for a combined total of approximately $80 million. "Since August 2015, we have now announced or closed non-core asset sales of approximately $1.3 billion, surpassing our targeted range of $750 million to $1 billion," said Marathon Oil president and CEO Lee Tillman. "Ongoing portfolio management continues to drive the simplification and concentration of our portfolio to lower risk, higher return U.S. resource plays and support our 2016 objective of balance sheet protection."