ACCUMULATION HISTORY OF THE DAERQI OIL POOL IN THE BAIYINCHAGAN SAG, THE ERLIAN BASIN

The Daerqi structure is a very important oil-bearing structure in the Baiyinchagan Sag,the Erlian Basin.Based on seismic lines,hydrocarbon source rock,lithology,thermal stream and test data,a two dimensional forward model of the basin has been made.Histories of filling,thermal stream,maturity,hydrocarbon generation,discharge and migration are analyzed.Oil mainly deposits in the Tenggeer Formation and the lowest part of the Duhongmu Formation in the Daerqi structure.In the western nose of the Daerqi structure,oil in the lowest part of the Duhongmu Formation mostly locates below the Baiyin fault and oil in the Tenggeer Formation mostly locates upon the Baiyin fault.In the eastern nose of the Daerqi structure,oil mostly deposits in the lowest part of the Duhongmu Formation and oil in the Tenggeer Formation mostly locates in the higher structure.Accumulation evolution of the Daerqi structure can be divided into four periods:the first accumulation period,the second accumulation period,the scattering period and the stable period.The first accumulation period is the main accumulation period.Oil scatters in the lower position.Accumulation history of the Tenggeer Formation is more complicated than that of the lowest part of the Duhongmu Formation.The southern slope is the main target of petroleum migration and should be focused on.