Sedimentary Microfacies Of Yangdachengzi Oil Layer In Chao 94 Block In Northern Songliao Basin

In order to study the sedimentary microfacies characteristics of the Yangdachengzi oil layer in the Chao 94 block in the northern Songliao Basin and to guide the next development of the oil field,under the research of regional geological background in Chaoyanggou area in the northern Songliao Basin,based on theoretical knowledge of sedimentary petrology and oil and gas field development geology,combined with core,logging,seismic and other data,establish an isochronous stratigraphic framework in the study area,the provenance direction and sedimentary microfacies of the study area are studied,and the evolution law of sedimentary microfacies is summarized.The research results show that:(1)Comprehensive use of core,well logging and other data,based on newly completed closed core wells,combined with other key wells to classify the study area,the study area is divided into 22 small layers and 47 sedimentary time units.On this basis,a small layer comparison of the whole area was carried out,and an isochronous stratigraphic framework was established.(2)Under the control of the fine isochronous stratigraphic framework,combined with previous research results,a comprehensive analysis of the provenance of the study area was completed.It is believed that the Yangdachengzi oil layer in the study area is a provenance confluence area,and a large area is a southwestern provenance control area.Among them,the types of heavy mineral assemblages in the Yang III and Yang II oil-bearing formations are mainly epidote,garnet or epidote,and zircon,while the heavy mineral assemblages of the Yang I oil-bearing formation are epidote,magnetite and zircon.(3)Based on the closed coring wells,6 types of logging curves were selected to identify1 facies,4 subfacies and 6 microfacies in the study area.The 6 sedimentary microfacies are the main channel,non-main channel,abandoned channel,main overflow sand,overflowing sand and floodplain microfacies.(4)Combining the analysis results of single-well facies and connected-well facies,the plane distribution characteristics of sedimentary microfacies in the study area were finely described,and the main sedimentary time units in the study area were identified as Yang I7₁,Yang I7₂,and Yang II5₂.The distribution of the plane sedimentary microfacies of the depositional time unit is described,and the development of the river channels in the study area is analyzed:it is believed that most of the river channels in the study area are distributed in a southwest-northeast direction,with a large number of channels,and most of the deposition time units have developed at least 3 There are more than one river course,the widest part of the river course can reach 2200m,and the narrowest part can reach100m.(5)According to the plane distribution law of sedimentary microfacies in the study area,combined with the development characteristics of sand bodies,the vertical evolution law of sedimentary microfacies in the study area is analyzed,and it is concluded that:During the process of sedimentary evolution in the study area,the energy of the water body was turbulent,the direction of the river channel fluctuated frequently,and the scale and quantity of the river channel were constantly changing,which led to the complex development of sand bodies in the study area.Through the study of sedimentary microfacies in the study area and the analysis of the evolution of sedimentary microfacies,it provides a favorable basis for the next development measures,and also provides effective help for determining the"sweet spot"area of advantageous reservoirs in the future,it is of great significance to the oil and gas exploration in the study area.