Sedimentary Sequence Evolution and Reservoir Characteristics in the Changling Area,Songliao Basin

By studying how base level and accommodation space change the strata between the forth member of Quantou Group and the first member of Nenjiang Group in Changling Depression Basin.The sequence stratigraphy has been devided into five third sequences and eight forth sequences,and high resolution sequence formation framework has been built up.Double delta sediments and lake sediments superimposed vertically because of two-stage cycles of lake level.By analysising the relationship between elements of reservoir and development of sedimentary sequence in the sequence framework,the formation in depression contained three sets of allied reservoir plays.The lower play had good genetic conditions and the middle one's conditions were also good if migration pathway were unblocked.The rule of reservoir formed in this area has been concluded as follows.Firstly,sequence and cycle controlled where petrol accumulate and the main reservoirs lay near hydrocarbon rocks.Secondly,sedimentation zone controlled the distribution of reservoir,delta front sand bodies which contained more and better oil and gas were good reservoirs.In accordance with restriction of reservoir factors' combination and distribution,it is predicted that good reservoir of Changling area distributed in delta front and shore-near crossover region.