In Feb.1955

it was decided in the First National petroleum prospecting Conferencc of the Ministry of Geology that a nation-wide petroleum prospecting sould be carried out.As a result

the Huabei petroleum prospecting Brigade and No.226 Geophysical Exploration Team were set up in the same year

and advanced on Huabei Basin.Since then

large scale prospecting-explorationtasks were carried out in plains and the surrounding mountainous areas in Liaoning

Shandong

Hebei

Henan and Anhui Provinces.At first

main taregt was put on the paleozoic oil and gas

later on

major geological tasks were led to Tertiary System in Jiyang and Huanghuadepressions.Soon afterwards

some subtle structures

such as Dongying

Sheng-licun

Tuozhuang and Yangsanmu structures were discovered.In 1960-1961

the Tertiary dark rock—the Jiyang Group and the Shahejie Formation—favour-able for oil generation

is discovered in wells Boxing-1 and Hua-7

Tertiaryoil sands were also discovered in well Dengqin-3.Based on these inspiring achievements

the Ministry of Geology called together an important stratigicmeeting—Tianjin symposium—in Nov.1960

and resoluted that Jiyang andHuanghua depressions should be taken as the main exploration area and dis-pose correspondent forces.At the same time

the Ministry of Petroleum Industry had also deployed impressive exploration strength and deep drill rigs.Breakthroughs were soon achieved. In 1961

commercial oil flows out from theDongying and Yangsanmu structures

thus laid a foundation for the settingup of Shengli and Dagang oilfields.Later

in 1963

oil flow was drilled atin Fengheying structure in the suburb of Beijing in Jizhong depression.In1964—1965

Lower Tertiary oil sand was drilled at in Huangjindai structurein Xialiaohe depression

and this resulted in the rapid discovery of Liaohe oilfield.In 1973

oil-trace was discovered at last on top of dolomitilized siliceous limestone in the Sinian Wumishan Formation in well Jimen-1 ofRenqiu structure after a lot of failures.In 1975

large amount of commercial oil flows out from well Ren-4 in the Sinian buried-hill within the same structure

thus led to the foundation of Huabei oilfield.