Shares of Anadarko Petroleum (APC), along with those of its partners in a deepwater Gulf of Mexico exploration project, are higher after the companies reported a large oil discovery. Anadarko said its "Shenandoah-2" well encountered more than 1,000 net feet of oil pay, marking "one of Anadarko's largest oil discoveries in the Gulf of Mexico." In its own press release, Cobalt International Energy (CIE) confirmed the Shenandoah-2R appraisal well encountered more than 1,000 net feet of oil pay, compared to the Shenandoah-1 discovery well, drilled in early 2009, which encountered more than 300 net feet of Inboard Lower Tertiary oil pay. Anadarko stated it is the operator of the Shenandoah-2 well, and the previously announced Shenandoah-1 discovery well, with a 30% working interest. Co-owners in Shenandoah include Cobalt with a 20% working interest, ConocoPhillips (COP) with a 30% working interest, Marathon Oil (MRO) with a 10%working interest and Venari Resources with a 10% working interest. In a note to investors this morning, Wells Fargo estimated the new well could increase Anadarko's value by about $4 per share based on the value of two of the company's prior projects. In trading prior to the opening bell, Anadarko shares rose about $2.70, or 3.3%, to $86.00, while Cobalt gained 7.2% to $27.65 and ConocoPhillips advanced 1.4% to $60.12.