| In this paper,starting with the division of the single well formation,through the analysis of the first hand data of a large number of drilling and laboratory tests,the well seismic combination is used to accurately calibrate the layers,to elaborate the faults,to realize the rational combination of faults,to analyze the history of tectonic development and to improve the accuracy of the tectonic map.On this basis,the sedimentary facies plane distribution can be predicted by dividing the sedimentary facies of single well.The lateral variation of reservoir is predicted by profile inversion,and the sand body distribution prediction under facies control is carried out.In addition,through the analysis of the organic geochemical indexes of all single wells in the study area,the source rock evaluation and resource potential analysis are carried out according to the abundance of organic matter,the type of kerogen,the composition of crude oil,the thickness of the effective source rock.Combined with the known reservoir anatomy,the factors that affect the oil and gas bearing factors are analyzed,and the oil and gas accumulation rules are found through the structural evolution,the zone is evaluated,and the favorable traps and drilling targets are determined.The main results are as follows:(1)The Bayanhushu sag is generally a gentle slope,and develops the structural pattern of the three rises and three depressions.The faults of synsedimentary fault and late fault depression are mainly distributed in NE direction,followed by north-south direction.During the late Jurassic period,the sag began to take shape,and the sag of the Nantun formation was in a stage of great subsidence.Before the deposition of the Damoguaihe group,the depression recessed again.Before the Yimin formation,the reverse tractive structure of the steep slope was formed;before the late Cretaceous deposit,the depression was integrated,and the late Cretaceous and Cenozoic tectonic activities were weak,and the characteristics of the depression were more obvious.(2)There are alluvial fans,rivers,fan deltas,shallow lakes,shallow lakes and deep lakes in Bayanhushu fault depression.The subfacies of fan delta front are retained,mainly including subaqueous distributary channel,estuarine dam,fan margin,mat sand,and underwater distributary channel.(3)The source rocks of the Bayanhushu sag are mainly developed in the Nantun formation,mainly in the middle and southern sag of the depression,which are lacustrine dark mudstones.The abundance of organic matter is uneven,the quality is good,and the evolutional stage is obvious.(4)The sandstone reservoirs in the Bayanhushu depression were developed in the Tongbomiao formation,the Nantun formation and the Yimin formation,which are mainly distributed in the edge of the depression,mainly siltstone,and are very low permeability reservoirs.(5)The oil and gas in the Bayanhushu depression are mainly distributed in the middle subsag of the depression,followed by the western step fault zone and the eastern gentle slope zone two steps.The oil and gas accumulation is mainly controlled by 4 factors:? the distribution of mature hydrocarbon source rocks in the crude oil trough control the range of oil and gas enrichment,?the sandstone and gravel are the main reservoirs of oil and gas,?the tectonic zone controlled by the main fault is the favorable zone for the accumulation of oil and gas reservoirs,?the unconformities in the mature oil reservoirs control the accumulation of oil and gas.(6)There are 42 tectonic traps in five tectonic layers in Bayanhushu sag,and 4 favorable traps are selected as exploration targets,respectively,the Hal trap,the Ha3 trap,the A1 trap and Ha4 trap. |
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