China National Petroleum Corp (CNPC), the mainland’s largest oil producer, is considering a bid for a minority stake in shale gas assets owned by US firm Chesapeake Energy, the South China Morning Post reported. The stake is valued at about US$15 billion. The Chinese firm declined to comment to the paper. Chesapeake has previously said it plans to raise as much as US$5 billion this year from the sale of stakes in the two assets in Arkansas and Pennsylvania. A Chesapeake spokesman told the paper that the firm is "entertaining possible partnerships" on the assets but declined to name any of the firms involved. That CNPC is seeking a minority stake, and that the US has large amounts of undeveloped shale-gas reserves, may help the Chinese oil firm overcome political obstacles to possible deal.