Shallow Water Delta Depositional System Reserch In Fuyu Reservoir Of Daqing Placantcline

The dissertation is directed by high resolution sequence stratigraphy and sedimentology.Based on cores study and seismic data analysis,the shallow water delta depositional system of Daqing Placantcline is illustrated comprehensively.During the deposition of Fuyu reservoir at Daqing Placantcline,the Songliao Basin was undergoing the stable depression period.According to paleogeomophic study,there had low gradient slope and wide shallow lake at Daqing Placantcline when F1 deposited.There exists a lake transgression depositional process and the accommodation space gradually increases.So there exist favorable paleogeography conditions and environmental conditions to deposite shallow water delta.Through sedimentary facies analysis,the shallow water delta develop in F1 and only develop delta plain and delta front.The microfacies contain distributary channel,distributary interchannel,crevasse splay complex,sand sheet,expanding contracting lake mudstone,interchannel lake mudstone and stable lake mudstone.On the basis of depositional process and sedimentary facies study,the fourth and the fifth order base level cycle boundary are recognised.There exist two kind of transgressive cycles which are diapause transgressive cycle and sustained transgressive cycle.During the diapause transgressive depositional cycle,the accomodation space changed slowly,the anastomosing river sediment deposited early(bottom of F12)and the shallow water delta plain sediment deposited later(top of F12).During the sustained depositional transgressive cycle(F11),the accomodation space changed quickly,the shallow water delta front sediment deposited.There had four kind of the fifth order base level cycle boundary recognised,which are ravinement surface of channel,paleosol caliche surface,crevass splay thickness transfer surface and stable mudstone depositional sequence.High resolution sequece stratigraphy frame was established based on base level cycle study,well-seismic sequence study and fluvial stata correlation strategy.Through sediment source analysis,sedimentary facies study and skeleton sandstone thickness analysis,the shallow water delta's distributary characteristics was forecasted.According to sedimentary facies distributary characteristics analysis,The Fuyu reservoir in Daqing Placantcline experienced anastomosing deposition to shallow water delta deposition process.During diapause transgressive depositional cycle,there developed anastomosing depositional system and shallow water delta plain at study aera.During the sustained depositional transgressive cycle,there mainly developed shallow water delta front with the accomodation space increase.This study will be helpful for remaining oil exploration.