Eni (NYSE:E) announced today that it would sell a 28.57% share of its stake in Mozambique's Area 4 offshore natural gas prospect to China National Petroleum Corp. (CNPC). The deal will leave Eni with 50% ownership of Area 4, and CNPC will hold 20%, according to Eni's press release. The transaction is subject to Mozambican authorities' approval.

Eni describes the $4.21 billion deal as "strategically important" because of CNPC's "worldwide relevance ... in the upstream and downstream sectors." The company describes the sub-Saharan region as a key development hub in its 2013-2016 strategic plan. Eni's Mozambique casebook page explains, "exceptional overall potential of the gas discoveries already made, estimated at 1.974 billion cubic metres of gas in place (70 tcf), opens up extraordinary development opportunities in Asia, where energy demand is growing at a rapid pace."

Eni and CNPC also signed a Joint Study Agreement for cooperation in developing the Rongchang shale gas block, which covers roughly 2,000 square kilometers in China's Sichuan Basin. The Rongchang shale is close to China's main consumption markets. Research and production tests in nearby blocks have shown the Rongchang shale to be China's most promising so far. 

CNPC has made no public statement on the transaction.