JINAN, March 6(Xinhuanet)-- The Shengli Oilfield, the country's second largest oil field in east China's Shandong Province, turned out 26.74 million tons of crude oil in 2004, the highest in the past four years, according to the local source.

Gas production hit 900 million cubic meters, the highest during the past six years, the source said.

In addition, oil and gas reserves equivalent to 28.12 million tons were discovered last year, keeping the balance between extraction and the newly-increased reserves for eight years running.

The oil field has curbed the decline in oil and gas production during the past few years after breakthrough has been made in the geological exploration theories. It has developed four sets of technologies dealing with various types of the covert geological layers for further oil and gas reserves.

With the help of the unique theories, 646 million tons of oil reserves has been verified in the covert geological layers.

Moreover, the oil field has stimulated the development of both the old and new production areas with additional production capacity topping 1.32 million tons and 1.28 million tons, respectively.