Shell Oil Company, a subsidiary of Royal Dutch Shell plc, has reached an agreement for the sale of its interest in Deer Park Refining Limited Partnership, a 50-50 joint venture between Shell Oil Company and P.M.I. Norteamerica, S.A. De C.V. (a subsidiary of Petroleos Mexicanos, or Pemex). The transaction will transfer Shell's interest in the partnership, and therefore full ownership of the refinery, to Pemex, subject to regulatory approvals.