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.
