High Resolution Sequence Stratigraphy And Sedimentary Microfacies Of The Third Member Of Baikouquan Formation In Ma 18 Well Area Of Aihu Oilfield

Ma 18 well area in Aihu Oilfield is located on the west slope of the Mahu sag,Junggar Basin.The structure is simple,and a gentle slope with a tilt to the south-east as a whole.With the acceleration of exploration and development,the oil-bearing pattern of fan-control large-area continuous sheet accumulation in Baikouquan formation is more specific.The first member has been developed as the main layer.The second member is left as further development layer and is developed recently.In the early stage,it is considered that the third member is main comprised of front fan delta mudstone.Development value is little.However,with the further study and exploration,some layers' sand body develop better.Oil and gas display in logging and oil test data.whether the third member of the Baikouquan formation can be used as a reservoir need to be studied further.In response to this problem,under the guidance of high-resolution sequence stratigraphy,the formation of each well in the study area has been divided and contrasted.Thus,a stratigraphic framework based on fine division of high resolution sequence stratigraphy is constructed.Core observation and sedimentary characteristics of 4 coring wells have been analysised.Combined with the previous point of view,sedimentary facies ~ microphase types of the third member of Baikouquan formation in M18 well area have been determined.The corresponding relationship between microfacies and logging is established.The energy unit in the study area is divided into fan deltas front subfacies and anterior fan deltas subfacies.The microphase types are divided into the end of underwater shunt channel,the edge of underwater shunt channel,the main body of sheet sand,sheet sand,the edge of sheet sand,the estuary dam the,far sand dam and the front fan delta mud,and all kinds of sedimentary microfacies are described in detail.At the same time,the sedimentary phase plane study is carried out in the formation framework with ultra-short-term base level cycle as the correlation unit,and the sedimentary microphase plane diagram is compiled.On the basis of this,the vertical and planar evolution of sedimentary facies of the three member is analyzed,and the sedimentary facies model of the member is established.In the process of research,the interface of subsequence at all levels is identified,divisied and descripted.According to comprehensive application of standard well characteristics,Optimal selection of skeleton profile in the area and well-seismic combination sequence control and other methods,high-resolution sequence stratigraphic framework of a middle cycle,2 short-term cycles and 4 ultra-short-term cycles in the third member of Baikouquan formation has been established.On this basis,the plane distribution characteristics and vertical overlap model of sand bodies in the study area are described.The characteristics of reservoir physical properties and interlayer distribution are analyzed.The oil saturation is calculated.The main controlling factors of reservoir are analyzed.Based on the analysis of test oil conclusion,lithology,physical properties and plane distribution of sedimentary microfacies in the study area,It is pointed out that the favorable exploration third member and the futher area for exploration and development in the later stage of Xinjiang Oilfield.