THE GENESIS AND INFLUENTIAL FACTORS OF LAYERED RESERVOIR OF YELI-LIANGJIASHAN FORMATION IN THE JIYANG DEPRESSION OF THE BOHAI BAY BASIN

It was discovered that abundant isolated vug occurred in the Yeli-Liangjiashan Formation of Ordovician in the Jiyang Depression of the Bohai Bay Basin,which would turn into effective reservoir once connected by fractures.The article applied the seepage reflux mechanism developed by K.S.Deffeyes in 1965 to interpret the genesis of the dolomite of the Yeli-Liangjiashan Formation,and raised that regional weathering crust was formed by Huanyuan tectonic movement,which resulted in regional uplifting in the end of Early Ordovician,and that a great quantity of weathering crust vugs were deve-loped on the basis of dolomitisation.After these isolated vugs in the formation connected by the large mounts of fractures,which were generated by later fracturing reformation,the effective dolomite reservoir was formed.At the same time,the later faults linked up the atmospheric water and the lake water and reconstructed the reservoir by secondary corrosion.So the conclusion was that the development and its scale of this kind reservoir were controlled by later fracturing.