A newly found oilfield in Bohai Bay has a reserve of one billion tons, or about 7.35 billion barrels, the largest discovery in China over four decades, announced the China National Petroleum Corporation (CNPC) on May 3.

The oilfield lies in the Nanpu block of the CNPC's Jidong Oilfield in Caofeidian in Tangshan City, north China's Hebei Province.

The Nanpu block, partly offshore, covers an area of 1,300-1,500 square kilometers and is expected to produce light crude. It is an uncompartmentlized high-grade oilfield with average oil layer thickness of 80-100 meters and major target zone depth of 1,800-2,800 meters. Tested individual vertical well has a daily output of 80-100 tons, while 200-500 tons for individual horizontal well.

By 2004, CNPC had discovered five onshore oil fields in the Jidong area with a total reserve of 100 million tons and an annual output of 1 million tons.