Research Of High Resolution Sequence Stratigraphy Of Putaohua Oil Layer Of Member 1 Of Yaojia Formation In Northern Qijia-Gulong Depressionarea Of Songliao Basin

Qijia-Gulong Depression is located west of Daqing Changyuan in Songliao Basin.It is rich in oil and gas resources and is a key oil and gas exploration area in Daqing Oilfield.The northern grape oil layer in the Qijia-Gulong depression also has greater resource potential.Among them,important oil and gas fields have been found in the Haerwen area.However,due to the thin reservoir thickness and rapid changes,the exploration and development of late lithologic oil and gas reservoirs is difficult.High resolution sequence stratigraphy can provide an important basis for the exploration and development of hidden reservoirs in the area.Therefore,this paper carries out research on high resolution sequence stratigraphy and implements the laws of sedimentary filling evolution,thus providing an important basis for the later exploration and development of oil and gas.In this paper,by reviewing the previous research results,using the idea of "point-line-face-body",a high resolution sequence study was carried out on the northern grape oil layer in qijia-gulong depression in songliao basin.Firstly,the characteristics of the rock facies and sedimentary microfacies in the north of Qijia-Gulong depression were identified by means of fine core observation and well data analysis.Secondly,the identification mark of grapefruit oil layer sequence interface is clearly defined.On the basis of this,the stratigraphic framework of grapefruit oil layer in the northern part of Qijia-Gulong depression in Songliao Basin is established.Finally,the characteristics of the sedimentary system in the high resolution sequence lattice are analyzed,and the evolution laws of the sedimentary layer of grape oil in the area are clearly studied.The main results of the paper are as follows:Through the fine observation and description of the core in the coring well,it is determined that there are three major rock phases in the development of the grape oil layer in the research area,including mudstones,siltstones,and fine sandstone.Among them,mudstone can be divided into 5 types of mudstone facies,siltstone can be divided into 10 kinds of siltstone facies,and fine sandstone can be divided into 5 kinds of fine sandstone facies.The main sedimentary facies in the study area were identified as Delta facies and lake facies based on common phase markers such as rock type,sedimentary structure and paleontology.Among them,the delta phase is mainly a shallow water Delta leading edge sub-phase.Subfacies of the front edge of shallow water Delta include the underwater shunt channel microfacies,the mat sand microfacies,and the tributary interbay microfacies.The lake facies are mainly shallow lake subfacies,including sand dam microfacies and mud flat microfacies.Through the fine observation and description of the core in the coring well,it is determined that there are three major rock phases in the development of the grape oil layer in the research area,including mudstones,siltstones,and fine sandstone.Among them,mudstone can be divided into 5 types of mudstone facies,siltstone can be divided into 10 kinds of siltstone facies,and fine sandstone can be divided into 5 kinds of fine sandstone facies.The main sedimentary facies in the study area were identified as Delta facies and lake facies based on common phase markers such as rock type,sedimentary structure and paleontology.Among them,the delta phase is mainly a shallow water Delta leading edge sub-phase.Subfacies of the front edge of shallow water Delta include the underwater shunt channel microfacies,the mat sand microfacies,and the tributary interbay microfacies.The lake facies are mainly shallow lake subfacies,including sand dam microfacies and mud flat microfacies.The high resolution sequence interface identification mark of the North grape oil layer in the Qijia-Gulong depression:1.Regional unconformity surface and corresponding conformity surface;2.Bottom scour structure,rich in pebbles;3.Lithology and lithofacies transition interface;4.Logging phase marker and abrupt interface of logging curve.According to the research,the bottom interface of the North grape oil layer in Qijia-Gulong depression is an obvious erosion intersection,and the top interface is an obvious sedimentary transfer surface.Therefore,the grape oil layer in the study area is divided into an ascending long-term semi-cycle,which can be subdivided into three ascending mid-term semi-cycles and eight short-term cycles.Each short-term cycle is fully developed,mainly the ascending semi-cycle and the rising.The main asymmetric rotation.The grape oil layer in the study area was influenced by the source in the North,and was mainly deposited in shallow water Delta.From the bottom to the top,from Y1-SSC1 to Y1-SSC8,as the water body continues to deepen,the river channel gradually shrinks,showing the process of lake invasion and deposition.To sum up,this paper establishes the high resolution sequence stratigraphic framework of the study area by dividing and comparing the sequence of the northern research area of Qijia-Gulong depression.The study of sedimentary systems and sedimentary evolution rules in high resolution sequence strata framework will provide an important Geological basis for the search for favorable lithologic oil and gas reservoirs.